Nuvistor TV preamp mod
 

I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.


Jimmie

Nuvistor TV preamp mod
 

JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.


Jimmie

You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo ;-P

Nuvistor TV preamp mod
 

On Mar 18, 10:50*pm, RFI-EMI-GUY wrote:
JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.

Jimmie

You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo *;-P

I used to have access to the handbooks of the 60s and early 70s. I
thought those were some of the best years. Im always on the lookout
for some but it seems a lot of other people share my opinion and dont
want to part with them.

Jimmie

Nuvistor TV preamp mod
 

On Mar 19, 8:20*am, JIMMIE wrote:
On Mar 18, 10:50*pm, RFI-EMI-GUY wrote:



JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.

Jimmie

You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo *;-P

I used to have access to the handbooks of the 60s and early 70s. I
thought those were some of the best years. Im always on the lookout
for some but it seems a lot of other people share my opinion and dont
want to part with them.

Jimmie

Hey OM:

Really though sounds like you have low and high band VHF wideband
preamps for maybe TV use. The low band being 54 to 88 MHz and the
high band is 174 MHz to 230 MHz. So 6 and 2 meters is doable.

I don't know if you could squeeze UHF out of them, 6cw4s' input C is
way to high.
In tube TV's they used 6af4's for the UHF band half the input C of a
6cw4. And even that was a oscillator not a preamp.

73 OM

de n8zu

Nuvistor TV preamp mod
 

On Mar 19, 8:20*am, JIMMIE wrote:
On Mar 18, 10:50*pm, RFI-EMI-GUY wrote:





JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.

Jimmie

You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo *;-P

I used to have access to the handbooks of the 60s and early 70s. I
thought those were some of the best years. Im always on the lookout
for some but it seems a lot of other people share my opinion and dont
want to part with them.

They aren't that hard to find :-). The early-mid-60's handbooks would
be your best bet for finding Nuvistor construction articles.

But what you really want is to look up the 60's QST articles on
Nuvistor based preamps:

Sep 1960: Nuvistor as an RF Amplifier at 144 Mc
Jan 1961: K1IJB Nuvistor Preamplifier
Aug 1961: Nuvistor Preamplifiers for 50 and 144 Mc
Jul 1962: Nuvistor Converter for 220 Mc
Jul 1962: Improving Performance of Nuvistor 144 Mc converters
Aug 1962: Using the QST Nuvistor Converters with Amateur-Bands only
receivers
Jan 1963: An All-Nuvistor Convertor for 420 Mc
Apr 1963: Two Nuvistor Converters for 220 Mc
May 1963: Nuvistor Goes Mobile on 50 Mc

If you get the impression that early 60's was the peak for Nuvistor
usage, you'd be about right. The August 61 article is IMHO the
definitive one on preamp usage.

For using a TV preamp, all you'd want to do is remove any traps that
get rid of the ham bands. But you'd do much better with tuned input
circuit for only the ham band of interest.

You can download all the above for free from the ARRL if you log in
with your member ID. With all the old QST's available on the web,
everyone ought to be a member!

Tim N3QE

Nuvistor TV preamp mod
 

On Mar 20, 9:33*am, raypsi wrote:
On Mar 19, 8:20*am, JIMMIE wrote:





On Mar 18, 10:50*pm, RFI-EMI-GUY wrote:

JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.

Jimmie

You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo *;-P

I used to have access to the handbooks of the 60s and early 70s. I
thought those were some of the best years. Im always on the lookout
for some but it seems a lot of other people share my opinion and dont
want to part with them.

Jimmie

Hey OM:

Really though sounds like you have low and high band VHF wideband
preamps for maybe TV use. The low band being 54 to 88 MHz *and the
high band is 174 MHz to 230 MHz. So 6 and 2 meters is doable.

I don't know if you could squeeze UHF out of them, 6cw4s' input C is
way to high.
In tube TV's they used 6af4's for the UHF band half the input C of a
6cw4. And even that was a oscillator not a preamp.

73 OM

de n8zu- Hide quoted text -

- Show quoted text -

6cw4s may not be what is in the amps but I do have a few and a few
others. I thik the 6cw4s were something I bought for a project and the
others are left over from when I worked on TVs back in the early 70s.
They are probably the right kind. Im pretty sure I kept these preamps
because they worked because at one time I had a bushel of them most of
which had a fair amount of lightning damage.

Jimmie

Nuvistor TV preamp mod
 

"Tim Shoppa" wrote in message news:426c859e-943c
You can download all the above for free from the ARRL if you log in
with your member ID. With all the old QST's available on the web,
everyone ought to be a member!

Tim N3QE

I'll join the ARRL the day I can choose QEX over the QST
forced subscription that comes with the membership.

Pete k1zjh

Nuvistor TV preamp mod
 

"Unca Pete" writes:

I'll join the ARRL the day I can choose QEX over the QST
forced subscription that comes with the membership.

Pete k1zjh

Have you ever thought of JOINING ARRL, and using your position as
a member to petition for this change?

Change is made by those who participate.

--N1GAK

Nuvistor TV preamp mod
 

Unca Pete wrote:
"Tim Shoppa" wrote in message news:426c859e-943c
You can download all the above for free from the ARRL if you log in
with your member ID. With all the old QST's available on the web,
everyone ought to be a member!

Tim N3QE

I'll join the ARRL the day I can choose QEX over the QST
forced subscription that comes with the membership.

Pete k1zjh
================================================= =====================
Have you ever thought of JOINING ARRL, and using your position as
a member to petition for this change?

Change is made by those who participate.

--N1GAK
===============================
Agree with that ,although ARRL members should have a choice.
If they prefer QEX over QST they should have that option.
ARRL news is sent weekly by e-mail upon request .Moreover, members can
access QST articles via the ARRL web site, and also can access QEX articles.

Living in the UK I have opted for the annual CD-ROM ,which is published
in March ,including QST , QEX and the Contest Mag. covering the past
calendar year ,which suits me fine.
However I believe this option is not available to US residents .
Perhaps something to go for.

Frank GM0CSZ / KN6WH

Nuvistor TV preamp mod
 

"Lawrence Statton" wrote in message
...
"Unca Pete" writes:
Have you ever thought of JOINING ARRL, and using your position as
a member to petition for this change?

Change is made by those who participate.

--N1GAK

The name of the game is $$$$$.

They'd lose advertising revenues if folks were given the
choice. I vote with my WALLET; and I let them know it.
QST has been dumbed down to meet the needs of the
new 2x1 callsign holders--the ones who can't figure the
out how make a dipole or solder a PL-259. And the
fact they destroyed the competition (Communications
Quarterly) doesn't sit well with many of us.

Pete k1zjh

Nuvistor TV preamp mod
 

Highland Ham wrote in :
Unca Pete wrote:
"Tim Shoppa" wrote in message news:426c859e-943c
You can download all the above for free from the ARRL if you log in
with your member ID. With all the old QST's available on the web,
everyone ought to be a member!

Tim N3QE

I'll join the ARRL the day I can choose QEX over the QST
forced subscription that comes with the membership.

Pete k1zjh
================================================ ======================
Have you ever thought of JOINING ARRL, and using your position as
a member to petition for this change?

Change is made by those who participate.

--N1GAK
===============================
Agree with that ,although ARRL members should have a choice.
If they prefer QEX over QST they should have that option.
ARRL news is sent weekly by e-mail upon request .Moreover, members can
access QST articles via the ARRL web site, and also can access QEX articles.

Erm ... while I dislike contradicting you directly, I just tried to download a
QEX article, afer logging in to my ARRL.net account, and got the following:

: The ARRL Periodicals Archive and Search is both an index of articles and an archive of downloadable material. However, not everything in the index is available for download.
:
: The item you requested is not in the archive of downloadable information. This may be because:
:
: * Most QST material newer than 2005 is not available for download
: * QEX, NCJ and Ham Radio material is not available for download

I subscribe to QEX as well as QST, and really would like QEX to be downloadable.
I see in my future a letter to the Powers That Be.

--
Mike Andrews, W5EGO

Tired old sysadmin

Nuvistor TV preamp mod
 

"Highland Ham" wrote in message
...
===============================
Agree with that ,although ARRL members should have a choice.
If they prefer QEX over QST they should have that option.
ARRL news is sent weekly by e-mail upon request .Moreover, members can
access QST articles via the ARRL web site, and also can access QEX
articles.

Living in the UK I have opted for the annual CD-ROM ,which is published in
March ,including QST , QEX and the Contest Mag. covering the past calendar
year ,which suits me fine.
However I believe this option is not available to US residents .
Perhaps something to go for.

Frank GM0CSZ / KN6WH

The ARRL derrives a lot of income from the QST
advertisements. Decreased circulation numbers would cost
them revenue. I'm sure the answer would be increasing
the circulation figures for QEX, and making up the revenue
there, but the logistics might be too great. That's why the
QSTs are delivered on a timely basis stateside; stale 12
month old adds delivered by CD won't make the advertisers
happy. I've complained about this in the past (dumbing down
of QST) and was told that they are serving the majority
of the membership with the current content.

Anyway, I feel I might have hijacked Jimmies' thread, and
I'll stop posting with this last comment.


Pete

Nuvistor TV preamp mod
 

Lawrence Statton posted on Sat, Mar 21 2009 6:46 am

"Unca Pete" writes:

I'll join the ARRL the day I can choose QEX over the QST
forced subscription that comes with the membership.

Pete k1zjh

Have you ever thought of JOINING ARRL, and using your position as
a member to petition for this change?

Change is made by those who participate.

--N1GAK

CHANGE is made by those who cozy up to the Old Boys Network of the
League. The arch-conservatives there want only ONE thing: Preservation
of their rank/status/title and the ability to Rule. The rest is just
PR BS to convince members that They are 'for' members. As a voting
member of the ARRL (until end of March) for two years, I've gotten a
chance to 'vote' just once and then only for lower positions;
candidacy for Director was unopposed so the incumbent was
'automatically' elevated to another term. Some 'voting,' not.

As one who has been around the electronics industry for over a half
century, I KNOW all the styles of writing that are acceptable in
written correspondence. After three such carefully-structured
correspondences FAILED to get an answer (one Form Letter reply is not
counted as any sort of real reply), there wasn't any point of wasting
my time with them.

The Editor of QST seems technically inept but appears to have the
'company man.' The Editor of QEX is technically better but could spend
more time going over manuscripts to 'tighten up' some text and yield
more technical explanations in the same amount of pages. QST's flavor
of presentation is getting more and more like 'Ham Radio for Dummies.'
Ohm's Law of Resistance is apparently 'rocket science' according to
QST pages...if there is any in between the blitz of self-important PR
BS there. Bear in mind I've been (first) a contributor to, then
Associate Editor (for two years) at Ham Radio magazine back before
1990 and when I did not have any amateur radio license (just a First
'Phone granted in 1956).

Yes, if one wants (marginal quality) PDF downloads from QST since the
year dot, membership might be worth something. Most of those PDFs come
with an inserted first page of copyright warnings which is about 450
KB size all by itself, always the same page. Makes a lot of
difference in downloading over a dial-up connection. It is better to
just plain BUY a CD of selected years rather than download the same
thing over and over again. That has the advantage of greater monetary
revenue for the League...something They NEED to keep the paid high-
level staff in 6-figure annual incomes.

With paid membership (and its 'voting rights') comes a 3:1 ratio of
surface mail spam to BUY BUY BUY this and that as compared to actual
worthwhile news/information. Good copy, cleverly misinforms the
'lowered cost of shipping' (on 'specials') as 'member money savings.'
Never mind that I can go to HRO or AES outlets and get the SAME
product over the couner at the SAME price with NO shipping charges.
Shipping direct from Newington Hq means they are pocketing the
difference local stores make as profit for reselling, another small
revenue booster for the League. Not much, to be sure, but it denies
any real savings to paid members.

The usual rejoinder from League sycophants is "members get QST free!"
as if that were an excuse. Hello? The paid advertising space in ANY
hobby magazine pays the staff and most overhead (except fulfillment
services, aka mail subscription delivery) to keep everyone working.
CQ works that way, 73 and Ham Radio magazines worked that way as
Independent periodical publishers for years until the advertisers had
to tighten their economic belts. By virtue of being a virtual monopoly
on amateur radio publications, the ARRL can offer the widest exposure
to advertisers so, when economic chips started to deplete beginning
around 1990, advertisers gravitated to QST with its demographic
guarantee of about 120K 'sales' per issue back then.

Just WHAT has the ARRL gotten for YOU in the past decades? Their
influence with the FCC is dropping, witness all the Report and Orders
footnotes and denials on dockets 98-143, 05-235, and at least three of
the 18 Petitions for change in between those two landmark regulation
changes. The ARRL hasn't achieved any new bands on HF except for 5
channels at '60m.' They never got a whole band to play hams-are-vital-
and-important to the nation in times of crises. Five CHANNELS. As if
the 'technical experts' there had never seen the giant frequency
allocation chart in Part 2, Title 47 C.F.R. that shows where everyone
is allowed from 9 KHz to 300 GHz...nor did they seem to have a handle
on government radio use in HF. The 'WARC' bands came about in 1979
(at WARC-79) by the ITU, not the ARRL. ARRL has yet to join the rest
of the IARU in going for any LF bands for amateurs as they do in
Europe.

For an excellent peek into thinking of the higher-ups in the League,
just read their Minutes of Regional meetings. Most of it is just self-
congratulary high-fives among the insiders praising each other. WE
don't get to see any talks of 'change' (horrors!) in much of
anything. You might say the Spirit of AIG had invaded the ARRL long
ago. In between asking for More Money for the 'Spectrum Defense Fund'
and the 'Foundation' and 'Buying a Brick for the Diamond Terrace,'
Will the League soon be asking for 'bail-out money' from ongress? :-(

Len Anderson, AF6AY
Life Member, IEEE (a Professional Association)

Nuvistor TV preamp mod
 

AF6AY wrote:
Lawrence Statton posted on Sat, Mar 21 2009 6:46 am

"Unca Pete" writes:
I'll join the ARRL the day I can choose QEX over the QST
forced subscription that comes with the membership.

Pete k1zjh
Have you ever thought of JOINING ARRL, and using your position as
a member to petition for this change?

Change is made by those who participate.

--N1GAK

CHANGE is made by those who cozy up to the Old Boys Network of the
League. The arch-conservatives there want only ONE thing: Preservation
of their rank/status/title and the ability to Rule. The rest is just
PR BS to convince members that They are 'for' members. As a voting
member of the ARRL (until end of March) for two years, I've gotten a
chance to 'vote' just once and then only for lower positions;
candidacy for Director was unopposed so the incumbent was
'automatically' elevated to another term. Some 'voting,' not.


[...]

Ok, understood, although the ARRL Handbook was "the" eye opener for me
as a kid.

But:


Len Anderson, AF6AY
Life Member, IEEE (a Professional Association)
^^^^^^^^^^^^^^^^^^^^^^^^^^


Full disclosu I am also an IEEE member. However, despite numerous
efforts by myself and others they could not even get the virtual
communities off the ground and with that dreaded web interface they
insist on keeping they never will. Now I haven't given up yet and one of
the forum admins is also pushing to at least provide a parallel
newsreader access. It certainly ain't rocket science. We'll see.

Then the "professional" side of their member benefits such as the
Financial Advantage Program or FAP. Yesterday I called for the umpteenth
time because a new client of mine wants to see professional liability
insurance. The answer: As usual they will decline to quote because part
of my job is to design medical devices. The topper was when they told me
that the IEEE plan does not cover any work for a company outside the US
(this one is) even if we'd exclude medical devices. Almost dropped my
water bottle. Is the earth still flat and at the end of the oceans we'd
fall off of it? And here I thought they had made it into the 21st
century ...

Oh, and when I asked for a homeowners insurance quote a while ago the
answer was "no plans available for the county where I live". To be
honest, all this doesn't convey too much professionalism.

--
73, Joerg

Nuvistor TV preamp mod
 

On Mar 24, 3:44�pm, Joerg
wrote:

Full disclosu I am also an IEEE member. However, despite numerous
efforts by myself and others they could not even get the virtual...

You seem frustrated and are Venting about something that isn't even
remotely "homebrew." When you pick up on a signature, that is a sure
sign you are spoiling for some kind of Fight. shrug

I've been getting paid for moving electrons around, guiding fields and
waves for 56 years. I've been playing around with a slightly
different
area of electronics for 62 years as a pure hobbyist, not seeking some
kind of fame or notoriety or anything else, just for the fascination
of moving electrons the way I'd like them to move. I don't pretend to
be an "expert" in electronics or radio...just one who has been around
both the electronics industry (in rather different areas, not always
of my own chosing) and hobby electronics for a rather long time. I'd
thought that more people might be interested in some different ways to
do the same circuit tasks, therefore I suggested those from time to
time in places such as forums. Obviously not. Too many have THEIR
"best way" on things and what THEY do is "so much better." Sigh...

My enthusiasm for electronics got the better of me and, after a long
absence of not bothering to post anything in rec.radio.homebrew, I
brought up RELAYS as an ALTERNATE way of switching RF circuits at HF.
I will apologize for that since I can (obviously) see that some have
their "pet" ways of doing things and aren't open to suggestions.
------------------
I became a member of the IEEE late, in 1973. Dues-paying kind. Main
reason was to add to my WORK knowledge...that which paid for my
living.
I did not go into it for any "benefits" package advantages because I
had most such benefits already. I am not one to "fall" for
professional Advertising (I am a "hard sell" for all salespeople).
Under IEEE association bylaws, Life Membership is achieved solely by
tenure, no extra monies involved nor are accepted to achieve that.
On reaching Life Membership, NO dues are required, full membership
is free, and members get the informative membership magazine
"Spectrum" free every month. It is a Professional organization
because it is all about the Profession of electronics. I regard
myself as a "professional" for the simple reason of getting paid for
work in that field, like that work, like that play (as a hobbyist)
and have been doing it for over a half century. I've been fortunate
(sometimes unfortunate) to work in several varied disciplines within
electronics and got interested in those disciplines. Sometimes the
different techniques could apply themselves to hobby activities and
sometimes hobby experiments were useful in professional work. There
never has been a clear-cut demarkation line of technology between
avocational activies and occupational activities except as forced by
certain groups within the overall activity.

You will notice a "callsign" in my signature, that of an Amateur
Extra class callsign group assigned by the FCC. I did not bother
with getting my first-ever amateur radio license until some time
in January 2007 and then to pass all test elements on one Sunday
afternoon on 25 February 2007. I did that for two reasons: I was
able to do it (and had the chutzpah to do so); it was a
convenience to have the least restrictions on operation in what
MIGHT have been an enjoyable pasttime in my retirement (I still
work in electronics but only on my terms (therefore not often) and
not in "regular hours." I run into the SAME sort of "I SHOULD have
done it so-and-so" in nearly every field of endeavor where there
are CERTAIN ways that things "MUST be done."

In a burst of enthusiasm, I joined the ARRL immediately after
getting my federal amateur radio license grant (one cannot be a
voting member without that grant according to League rules). That
was another mistake I made. That AMATEUR organization membership is
expiring at the end of March and I am not renewing. As a hobbyist,
that AMATEUR membership has offered me almost NOTHING in return.
I have voiced my opinion on that AMATEUR organization in OTHER
forums, to the FCC on amateur radio regulations, and enought that
I don't wish to go into it here. Despite having started in big time
HF communications 56 years ago, long-time amateurs consider me a
"newbie," a "beginner in radio" and that is disheartening, taking
away much of my interest in ALL electronics.

In other forums NOT on amateur radio, I have been negatively
criticized for being a member of certain organizations that the
"expert" critics champion or dislike. For example, the ACM.
the first professional association about computing worldwide.
NOW, I see complaints about BENEFITS packages of the IEEE not
meeting with certain individual's approval. I am not a follower
nor an approver of Benefits Packages, nor a spokesperson of any
kind for of those. There is very little in ANY Benefits Package
that is of "benefit" in ANY homebrew electronics hobby activity.
I will emphasize HOMEBREW. Radio. Electronics.

For all my time spent working with, or being hobbyist in, electronics,
many and varied "experts" have TOLD me in no uncertain terms that
"This is the way 'we' do it in activity." I MUST do it as those
"experts" say. Sorry, but having been IN the activity for a long
time and watching the technology CHANGE, to have NEW ways and
components introduced since 1947, I have to throw that didactic
insistence (indeed a polemical philosophy) in the dumpster. If
someone finds/discovers/innovates something while engaged in
hombrewing some radio or other electronics, something NOT normally
done but still follows established laws of physics, then it should
be, in my viewpoint, be presented for other hobbyists. In the
spirit of that being a possible useful thing that others might be
able to use in their hobby activity. It should NOT be given in
terms of "look what *I* did" as some claim to "expertise." It
might be USEFUL to others in their hobby work. I feel that anyone
who wants to discuss matters totally different than a forum's
intended sphere of interest go find the appropriate forum to vent.

I've learned one more thing in Life here. Do not indicate one's
affiliation or pride or other personal feelings in a
"signature" of a posting...others do not like that. No matter,
my amateur radio license callsign can get my legal address.

Nuvistor TV preamp mod
 

On Mar 18, 10:50*pm, RFI-EMI-GUY wrote:
JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.

Jimmie

You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo *;-P

Well I got a little 2M nuvistor pre-amp put together last night. Im
not sure of the noise figure of the amp but according to my S meter it
must have about at least 20 db of gain, maybe 30.

I will have to take it into work were I have the test equipment to
check it out better.

Jimmie

Nuvistor TV preamp mod
 

On Mar 27, 3:59*am, JIMMIE wrote:
On Mar 18, 10:50*pm, RFI-EMI-GUY wrote:





JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.

Jimmie

You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo *;-P

Well I got a little 2M nuvistor pre-amp put together last night. Im
not sure of the noise figure of the amp but according to my S meter it
must have about at least 20 db of gain, maybe 30.

I will have to take it into work were I have the *test equipment to
check it out better.

Jimmie- Hide quoted text -

- Show quoted text -

Anyone know what kind of noise figure I could expect out of a 6cw4
nuvistor preamp. I only saw one reference and it mentioned 3db but
mostly all the other references just talked about gain.


Jimmie

Nuvistor TV preamp mod
 

On Mar 27, 8:22*am, JIMMIE wrote:
On Mar 27, 3:59*am, JIMMIE wrote:



On Mar 18, 10:50*pm, RFI-EMI-GUY wrote:

JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.

Jimmie

You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo *;-P

Well I got a little 2M nuvistor pre-amp put together last night. Im
not sure of the noise figure of the amp but according to my S meter it
must have about at least 20 db of gain, maybe 30.

I will have to take it into work were I have the *test equipment to
check it out better.

Jimmie- Hide quoted text -

- Show quoted text -

Anyone know what kind of noise figure I could expect out of a 6cw4
nuvistor preamp. I only saw one reference and it mentioned 3db but
mostly all the other references just talked about gain.

Jimmie

Hey OM

The reason you see those high noise figures: Carbon comp resistors
being used in tube circuits. The gain of the preamp amplifies the
noise of the carbon comp resistors. Best is to use metal film
resistors much lower noise.
And squeezing 20db out of a 6cw4 that has only gain of around 64 or
about 14 db is quite the feat.

73 OM
de n8zu

Nuvistor TV preamp mod
 

AF6AY wrote:
On Mar 24, 3:44�pm, Joerg
wrote:

Full disclosu I am also an IEEE member. However, despite numerous
efforts by myself and others they could not even get the virtual...

You seem frustrated and are Venting about something that isn't even
remotely "homebrew." When you pick up on a signature, that is a sure
sign you are spoiling for some kind of Fight. shrug


Not a pick of a fight, I am not that kind of guy. Has in part to do with
my other affiliation (church). I just found it a bit strange when you
blasted the ARRL and at the end in the sig line listed IEEE as a
professional organization. Which I do not see quite that way.


I've been getting paid for moving electrons around, guiding fields and
waves for 56 years. I've been playing around with a slightly
different
area of electronics for 62 years as a pure hobbyist, not seeking some
kind of fame or notoriety or anything else, just for the fascination
of moving electrons the way I'd like them to move. I don't pretend to
be an "expert" in electronics or radio...just one who has been around
both the electronics industry (in rather different areas, not always
of my own chosing) and hobby electronics for a rather long time. I'd
thought that more people might be interested in some different ways to
do the same circuit tasks, therefore I suggested those from time to
time in places such as forums. Obviously not. Too many have THEIR
"best way" on things and what THEY do is "so much better." Sigh...

My enthusiasm for electronics got the better of me and, after a long
absence of not bothering to post anything in rec.radio.homebrew, I
brought up RELAYS as an ALTERNATE way of switching RF circuits at HF.
I will apologize for that since I can (obviously) see that some have
their "pet" ways of doing things and aren't open to suggestions.


Not a pet way. All I wanted to do is show the pitfalls because newer
hobbysits need to be aware of those. For high-powered stuff I also use
relays, just as you do.


------------------
I became a member of the IEEE late, in 1973. Dues-paying kind. Main
reason was to add to my WORK knowledge...that which paid for my
living.
I did not go into it for any "benefits" package advantages because I
had most such benefits already. I am not one to "fall" for
professional Advertising (I am a "hard sell" for all salespeople).
Under IEEE association bylaws, Life Membership is achieved solely by
tenure, no extra monies involved nor are accepted to achieve that.
On reaching Life Membership, NO dues are required, full membership
is free, and members get the informative membership magazine
"Spectrum" free every month. It is a Professional organization
because it is all about the Profession of electronics. ...


I wish it was professional all the way, not just partly. The last FAP
mailer from them with the "professionality" level of a credit card
solicitation came Friday. Well, at least it was useful to start the wood
stove ;-)


... I regard
myself as a "professional" for the simple reason of getting paid for
work in that field, like that work, like that play (as a hobbyist)
and have been doing it for over a half century. I've been fortunate
(sometimes unfortunate) to work in several varied disciplines within
electronics and got interested in those disciplines. Sometimes the
different techniques could apply themselves to hobby activities and
sometimes hobby experiments were useful in professional work. There
never has been a clear-cut demarkation line of technology between
avocational activies and occupational activities except as forced by
certain groups within the overall activity.



That's a great career, when you can bring hobby experience into
professional work. Same here, but only about 25 years pro work
experience since my degree. Lots of homebrew electronics before that.
However, I don't see this kind of cross-fertilization between hobby and
professional life happen much in the next generation :-(


You will notice a "callsign" in my signature, that of an Amateur
Extra class callsign group assigned by the FCC. I did not bother
with getting my first-ever amateur radio license until some time
in January 2007 and then to pass all test elements on one Sunday
afternoon on 25 February 2007. I did that for two reasons: I was
able to do it (and had the chutzpah to do so); it was a
convenience to have the least restrictions on operation in what
MIGHT have been an enjoyable pasttime in my retirement (I still
work in electronics but only on my terms (therefore not often) and
not in "regular hours." I run into the SAME sort of "I SHOULD have
done it so-and-so" in nearly every field of endeavor where there
are CERTAIN ways that things "MUST be done."

In a burst of enthusiasm, I joined the ARRL immediately after
getting my federal amateur radio license grant (one cannot be a
voting member without that grant according to League rules). That
was another mistake I made. That AMATEUR organization membership is
expiring at the end of March and I am not renewing. As a hobbyist,
that AMATEUR membership has offered me almost NOTHING in return.


Ok, can't speak to that because I was a member in the German club
(DARC). But ARRL did one great thing for me: Very low cost books, full
of very useful technical information. Lots of stuff and antennas were
built with the help of ARRL books.


I have voiced my opinion on that AMATEUR organization in OTHER
forums, to the FCC on amateur radio regulations, and enought that
I don't wish to go into it here. Despite having started in big time
HF communications 56 years ago, long-time amateurs consider me a
"newbie," a "beginner in radio" and that is disheartening, taking
away much of my interest in ALL electronics.


I remember that, in Germany call signs were issued in alphanumeric order
(like non-vanity license plates in most states here) and some hams had
the tendency of prejudice. Newer call sign ... aha, rookie. Which just
wasn't true in many cases.


In other forums NOT on amateur radio, I have been negatively
criticized for being a member of certain organizations that the
"expert" critics champion or dislike. For example, the ACM.
the first professional association about computing worldwide.
NOW, I see complaints about BENEFITS packages of the IEEE not
meeting with certain individual's approval. I am not a follower
nor an approver of Benefits Packages, nor a spokesperson of any
kind for of those. ...


Just my humble opinion: If an organization can't get commercial products
like FAP straight they ought to dump them and not keep them to make a
penny. It's unprofessional, no matter what organization. And PL
insurance is not a benefit, it's a paid commercial product that numerous
members direly need in this case. Note the other thing I mentioned, much
more important: Member forums, has to do with learning, helping others,
exactly what also happens in a hobby. It ain't rocket science to set
that up yet they blew it. Like you were with ARRL I was twice just about
to ditch my IEEE membership but didn't at the last minute. Haven't given
up hope yet, but I've learned that one has to be rather loud in the IEEE
to be heard. It seems there are strict hierarchies that slow things down
a lot. It should not be that way.


... There is very little in ANY Benefits Package
that is of "benefit" in ANY homebrew electronics hobby activity.
I will emphasize HOMEBREW. Radio. Electronics.


Right. Once you are retired, or mostly retired in your case, and insured
by Medicare none of that insurance stuff matters anymore. But it does
matter to the majority of members who aren't there yet. My advice to
them would be: If you can't offer it as a decent product, don't offer it
at all. Just like I (and probably you) would not want to be engaged in
an engineering project we didn't believe in.


For all my time spent working with, or being hobbyist in, electronics,
many and varied "experts" have TOLD me in no uncertain terms that
"This is the way 'we' do it in activity." I MUST do it as those
"experts" say. Sorry, but having been IN the activity for a long
time and watching the technology CHANGE, to have NEW ways and
components introduced since 1947, I have to throw that didactic
insistence (indeed a polemical philosophy) in the dumpster. If
someone finds/discovers/innovates something while engaged in
hombrewing some radio or other electronics, something NOT normally
done but still follows established laws of physics, then it should
be, in my viewpoint, be presented for other hobbyists. In the
spirit of that being a possible useful thing that others might be
able to use in their hobby activity. It should NOT be given in
terms of "look what *I* did" as some claim to "expertise." It
might be USEFUL to others in their hobby work. I feel that anyone
who wants to discuss matters totally different than a forum's
intended sphere of interest go find the appropriate forum to vent.

I've learned one more thing in Life here. Do not indicate one's
affiliation or pride or other personal feelings in a
"signature" of a posting...others do not like that. ...


Should be ok to do that. But people will see it and might react to it ;-)


... No matter,
my amateur radio license callsign can get my legal address.


Mine's DK9JK. Not active at all right now though. Once I retire I plan
to sit for the US license exam just like you did. Probably will start
back out on 15m and 40m, CW and SSB, and maybe some of the newer modes.

--
73, Joerg

Nuvistor TV preamp mod
 

On Mar 27, 10:37*am, raypsi wrote:
On Mar 27, 8:22*am, JIMMIE wrote:





On Mar 27, 3:59*am, JIMMIE wrote:

On Mar 18, 10:50*pm, RFI-EMI-GUY wrote:

JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.

Jimmie

You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Use only Genuine Interocitor Parts" Tom Servo *;-P

Well I got a little 2M nuvistor pre-amp put together last night. Im
not sure of the noise figure of the amp but according to my S meter it
must have about at least 20 db of gain, maybe 30.

I will have to take it into work were I have the *test equipment to
check it out better.

Jimmie- Hide quoted text -

- Show quoted text -

Anyone know what kind of noise figure I could expect out of a 6cw4
nuvistor preamp. I only saw one reference and it mentioned 3db but
mostly all the other references just talked about gain.

Jimmie

Hey OM

The reason you see those high noise figures: Carbon comp resistors
being used in tube circuits. The gain of the preamp amplifies the
noise of the carbon comp resistors. Best is to use metal film
resistors much lower noise.
And squeezing 20db out of a 6cw4 that has only gain of around 64 or
about 14 db is quite the feat.

73 OM
de n8zu- Hide quoted text -

- Show quoted text -

Yeah I used metal film on my preamp. I tossed all of my carbon
resistors a few years ago after I fixed a guitar amp for a friend and
he brought it back telling me how noisy it was. I traced the problem
back to the NOS(40 years) resistors I had used.

Like I said those were S meter db. :))

Jimmie

Nuvistor TV preamp mod
 

JIMMIE wrote:
On Mar 27, 3:59 am, JIMMIE wrote:
On Mar 18, 10:50 pm, RFI-EMI-GUY wrote:





JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.
Jimmie
You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Use only Genuine Interocitor Parts" Tom Servo ;-P
Well I got a little 2M nuvistor pre-amp put together last night. Im
not sure of the noise figure of the amp but according to my S meter it
must have about at least 20 db of gain, maybe 30.

I will have to take it into work were I have the test equipment to
check it out better.

Jimmie- Hide quoted text -

- Show quoted text -

Anyone know what kind of noise figure I could expect out of a 6cw4
nuvistor preamp. I only saw one reference and it mentioned 3db but
mostly all the other references just talked about gain.


From vague memory I think Geloso used them a lot and got a little under
4dB out of those on 144MHz. In case anyone needs a datasheet:

http://www.r-type.org/pdfs/6cw4.pdf

--
73, Joerg

Nuvistor TV preamp mod
 

On Mar 27, 12:43*pm, Joerg
wrote:
JIMMIE wrote:
On Mar 27, 3:59 am, JIMMIE wrote:
On Mar 18, 10:50 pm, RFI-EMI-GUY wrote:

JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.
Jimmie
You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Use only Genuine Interocitor Parts" Tom Servo *;-P
Well I got a little 2M nuvistor pre-amp put together last night. Im
not sure of the noise figure of the amp but according to my S meter it
must have about at least 20 db of gain, maybe 30.

I will have to take it into work were I have the *test equipment to
check it out better.

Jimmie- Hide quoted text -

- Show quoted text -

Anyone know what kind of noise figure I could expect out of a 6cw4
nuvistor preamp. I only saw one reference and it mentioned 3db but
mostly all the other references just talked about gain.

*From vague memory I think Geloso used them a lot and got a little under
4dB out of those on 144MHz. In case anyone needs a datasheet:

http://www.r-type.org/pdfs/6cw4.pdf

--
73, Joerg- Hide quoted text -

- Show quoted text -

Thanks, I was just trrying to finish up a project I started years ago,
my wife had been getting on to me about not completing what I start.
Tinkering with the nuvistors also sounded like fun. Well I now realize
why you dont see projects based on them and noone is scouring the
tables at the hamfest looking for nuvistors. There are better/easier
of ways of skinning this cat. A DC to Daylight preamp using a MMIC
may well have better NF and gain.

Jimmie

Nuvistor TV preamp mod
 

JIMMIE wrote:
On Mar 27, 12:43 pm, Joerg
wrote:
JIMMIE wrote:
On Mar 27, 3:59 am, JIMMIE wrote:
On Mar 18, 10:50 pm, RFI-EMI-GUY wrote:
JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.
Jimmie
You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Use only Genuine Interocitor Parts" Tom Servo ;-P
Well I got a little 2M nuvistor pre-amp put together last night. Im
not sure of the noise figure of the amp but according to my S meter it
must have about at least 20 db of gain, maybe 30.
I will have to take it into work were I have the test equipment to
check it out better.
Jimmie- Hide quoted text -
- Show quoted text -
Anyone know what kind of noise figure I could expect out of a 6cw4
nuvistor preamp. I only saw one reference and it mentioned 3db but
mostly all the other references just talked about gain.
From vague memory I think Geloso used them a lot and got a little under
4dB out of those on 144MHz. In case anyone needs a datasheet:

http://www.r-type.org/pdfs/6cw4.pdf

--
73, Joerg- Hide quoted text -

- Show quoted text -

Thanks, I was just trrying to finish up a project I started years ago,
my wife had been getting on to me about not completing what I start.


Somehow this sounds quite familiar :-)


Tinkering with the nuvistors also sounded like fun. Well I now realize
why you dont see projects based on them and noone is scouring the
tables at the hamfest looking for nuvistors. There are better/easier
of ways of skinning this cat. A DC to Daylight preamp using a MMIC
may well have better NF and gain.


True, but tubes and even those tiny ones do have one distinct advantage.
When a thunderstorm rolls through town or you accidentally transmit into
your pre-amp their chance of survival is orders of magnitude higher.
Just imagine, when placing a hard 50V spike onto the grid a tube won't
even flinch. A GaAs-FET or MMIC? Tsssk ... *BANG*.

I realized this early on after getting my license. The transistor in the
pre-amp on the roof had died for the umpteenth time during a
thunderstorm. But this time the moss on the roof was quite thick and I
almost slid down. Whew! That did it. Built one with a tube (army
surplus, NOS, long lifetime version), and it never died again. Oh yeah,
and more than once did I accidentally transmit into the back of it. Left
it completely unfazed. Losing a dB or two in noise figure for the sake
of not having to scale that roof was well worth it :-)

I have seen Russians offer cartons full of nuvistors on auction sites,
they almost look like bonbon boxes. They must have a sizeable stash of
those over there.

--
73, Joerg

Nuvistor TV preamp mod
 

On Tue, 31 Mar 2009 20:37:58 -0700, Joerg
wrote:

JIMMIE wrote:
On Mar 27, 12:43 pm, Joerg
wrote:

From vague memory I think Geloso used them a lot and got a little under
4dB out of those on 144MHz. In case anyone needs a datasheet:

http://www.r-type.org/pdfs/6cw4.pdf

According to this page
http://www.amsat.org/amsat/archive/a.../msg00451.html
Geloso got 3.6 dB@50/144 MHz to 6.0 dB@432 MHz.

The VHF numbers are still usable at terrestrial VHF communication due
to the high band noise. For satellite and EME communication, the
performance it not very good at VHF and practically useless on UHF.


Tinkering with the nuvistors also sounded like fun. Well I now realize
why you dont see projects based on them and noone is scouring the
tables at the hamfest looking for nuvistors. There are better/easier
of ways of skinning this cat. A DC to Daylight preamp using a MMIC
may well have better NF and gain.


True, but tubes and even those tiny ones do have one distinct advantage.
When a thunderstorm rolls through town or you accidentally transmit into
your pre-amp their chance of survival is orders of magnitude higher.
Just imagine, when placing a hard 50V spike onto the grid a tube won't
even flinch. A GaAs-FET or MMIC? Tsssk ... *BANG*.

Most part of the lightning electromagnetic radiation is at quite low
frequencies (below 1 MHz) and a typical VHF/UHF antenna will have a
quite low effective height at such low frequencies, thus not much low
frequency energy should enter the preamp.

However, during thunderstorms, quite large static charges can be
accumulated in ungrounded antenna elements and if there is a DC path
to the transistor, there is a significant risk of damage.

Using a folded dipole and grounding the center point will reduce the
static build up. The folded dipole will also act as a very small
magnetic loop, reducing the LF pickup of the lightning EM pulse. A
strong DC path (such as a shorted 1/4 wavelength stub) from the
amplifier input to ground will also reduce the DC and low frequency
pickup, thus reducing the risk for dangerously large voltages at the
transistor base/gate.

Paul OH3LWR

Nuvistor TV preamp mod
 

Paul Keinanen wrote:
On Tue, 31 Mar 2009 20:37:58 -0700, Joerg
wrote:

JIMMIE wrote:
On Mar 27, 12:43 pm, Joerg
wrote:

From vague memory I think Geloso used them a lot and got a little under
4dB out of those on 144MHz. In case anyone needs a datasheet:

http://www.r-type.org/pdfs/6cw4.pdf

According to this page
http://www.amsat.org/amsat/archive/a.../msg00451.html
Geloso got 3.6 dB@50/144 MHz to 6.0 dB@432 MHz.

The VHF numbers are still usable at terrestrial VHF communication due
to the high band noise. For satellite and EME communication, the
performance it not very good at VHF and practically useless on UHF.


Although back in those days UHF was reserved for the more well-heeled
hams. I thought the 2m performance that old John got out of the
nuvistors was pretty good.


Tinkering with the nuvistors also sounded like fun. Well I now realize
why you dont see projects based on them and noone is scouring the
tables at the hamfest looking for nuvistors. There are better/easier
of ways of skinning this cat. A DC to Daylight preamp using a MMIC
may well have better NF and gain.

True, but tubes and even those tiny ones do have one distinct advantage.
When a thunderstorm rolls through town or you accidentally transmit into
your pre-amp their chance of survival is orders of magnitude higher.
Just imagine, when placing a hard 50V spike onto the grid a tube won't
even flinch. A GaAs-FET or MMIC? Tsssk ... *BANG*.

Most part of the lightning electromagnetic radiation is at quite low
frequencies (below 1 MHz) and a typical VHF/UHF antenna will have a
quite low effective height at such low frequencies, thus not much low
frequency energy should enter the preamp.

However, during thunderstorms, quite large static charges can be
accumulated in ungrounded antenna elements and if there is a DC path
to the transistor, there is a significant risk of damage.

Using a folded dipole and grounding the center point will reduce the
static build up. The folded dipole will also act as a very small
magnetic loop, reducing the LF pickup of the lightning EM pulse. A
strong DC path (such as a shorted 1/4 wavelength stub) from the
amplifier input to ground will also reduce the DC and low frequency
pickup, thus reducing the risk for dangerously large voltages at the
transistor base/gate.


The trouble in my case was that this thing was also used for the upper
shortwave bands, when doing duplex transmissions. Similar to what is
nowadays called an active antenna. I didn't have the space for a 2nd
large antenna, the first one was already quite a stretch. This was in
Germany where properties are quite tiny.

--
73, Joerg

Nuvistor TV preamp mod
 

On Mar 31, 11:16*pm, JIMMIE wrote:
On Mar 27, 12:43*pm, Joerg
wrote:





JIMMIE wrote:
On Mar 27, 3:59 am, JIMMIE wrote:
On Mar 18, 10:50 pm, RFI-EMI-GUY wrote:

JIMMIE wrote:
I have 3 mast mounted nuvistor pre amps less power supplies. I was
looking for information on these to convert them to use on the 6 and 2
meter *and 70cm ham bands. I may still have a power supply around but
as of yet I havent been able to find it. The pre amps are mount in a
somewhat egg shaped plastic container with twin lead connections on
them. Im not sure of the manufacturer. Schematics on the amplifiers
and power supplies would be nice. Directions on doing the mod would be
great. There are plans for ham band nuvistor preamps around so if I
could figure out what I have it shouldnt be that difficult to conver
it to what I want. Besides that it will give me something to do with
these old 6cw4s.
Jimmie
You would do good to find a 70's or earlier ARRL handbook. There were
many articles about Nuvistors.
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Use only Genuine Interocitor Parts" Tom Servo *;-P
Well I got a little 2M nuvistor pre-amp put together last night. Im
not sure of the noise figure of the amp but according to my S meter it
must have about at least 20 db of gain, maybe 30.

I will have to take it into work were I have the *test equipment to
check it out better.

Jimmie- Hide quoted text -

- Show quoted text -

Anyone know what kind of noise figure I could expect out of a 6cw4
nuvistor preamp. I only saw one reference and it mentioned 3db but
mostly all the other references just talked about gain.

*From vague memory I think Geloso used them a lot and got a little under
4dB out of those on 144MHz. In case anyone needs a datasheet:

http://www.r-type.org/pdfs/6cw4.pdf

--
73, Joerg- Hide quoted text -

- Show quoted text -

Thanks, I was just trrying to finish up a project I started years ago,
my wife had been getting on to me about not completing what I start.
Tinkering with the nuvistors also sounded like fun. Well I now realize
why you dont see projects based on them and noone is scouring the
tables at the hamfest looking for nuvistors. There are better/easier
of ways *of skinning this cat. A DC to Daylight preamp using a MMIC
may well have better NF and gain.

Jimmie- Hide quoted text -

- Show quoted text -

OH, what the heck,Since I got the preamp stage built I might as well
build a 2M to 10M rx converter.

Jimmie