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Old March 5th 07, 11:28 AM posted to rec.radio.amateur.moderated
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Default Tube equipment question

On Mar 4, 10:23�pm, Mike Coslo wrote:
* * * * I should have noted large range and balanced/unbalanced output. My
IC-761 has an autotuner on it that works pretty well with my vertical
antenna. The dipole is run with balanced line, and needs a different
tuner.


---

* * * * A little bigger components, plus a 4:1 balun, and they would have
it.

Well, sort of.

The Ancient Ones used antenna matching
devices to feed balanced lines. The Johnson
Matchboxes are one example of a commercial
version. Most Handbooks have examples of
link-coupled balanced wide-range tuners.

The problem was that such link-coupled tuners are large
and not easy to bandswitch.

About 1970, a new idea in tuners appeared: Use an
unbalanced matching network such as a T or L
network with a roller inductor or tapped inductor, with a
balun if balanced output was wanted. 4:1 iron-core toroid
baluns were compact and broadband, the T or L tuner
could be made wide-range without complex bandswitching,
and the whole works seemed an improvement on the old
link-coupled balanced tuner.

The problem was that baluns aren't magic devices. The
system works well if the shack-end of the transmission line
is around 200 ohms impedance and not too reactive. But in
many cases the shack-end impedance with balanced line
is very high or very low, and/or very reactive. Under such
conditions the balun may not do a very good job because it is
being asked to work far outside its design parameters.

Also, if the shack-end impedance is low (say, 12 ohms), the
use of a 4:1 balun will make it so low (3 ohms) that it may be outside
the efficient matching range of the T or L network.

These conditions may be partially remedied by use of a balun
that can be switched to either 4:1 or 1:1 ratio, and by choosing
antenna and feedline combinations that don't result in extreme
values of shack-end impedance/reactance. But that reduces
the flexibility of the system.

The "unbalanced tuner followed by a balun" idea is clearly
one where "newer" wasn't necessarily "better" in all cases.
Yet it became very popular because it usually worked.
But in many cases the balanced line was actually
doing a lot of radiating and there was considerable loss in the
system.

Back in 1990, AG6K came up with an answer to the
shortcomings of that method. He put a 1:1 balun between the
rig and a simple balanced tuner, so the balun only has to
deal with a pure 50 ohm load once the tuner is adjusted.
Although AG6K favors baluns made from coax wound on
PVC pipe, other forms of balun such as ferrite-bead and
wound-toroid can be used if preferred.

You can read AG6K's article he

http://www.somis.org/bbat.html

and judge for yourself.

AG6K's approach used two ganged roller inductors and
a single variable capacitor, compared to most commercial
manual tuners that use two variable caps and a single variable
inductor. Because there are only two controls, remoting the
tuner is made easier.

73 de Jim, N2EY



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Old March 5th 07, 01:36 PM posted to rec.radio.amateur.moderated
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Default Tube equipment question

Mike Coslo wrote:

A little bigger components, plus a 4:1 balun, and they would have
it.


I wish that the manufacturers would include the provision for balanced
feedline. The random-length dipole, fed with balanced line, is an ideal
antenna in many cases. It's especially appropriate for disaster
situations (and simulated disasters, like Field Day). Find the two
highest supports that are available, as far apart as possible, measure
the distance, cut the wire and install the middle insulator and
feedline, hoist each end, and you're done. Now you've got a reasonably
efficient radiator (especially if there's enough distance between those
two supports) that you can use on any band, and the length of the
feedline isn't particularly critical. But it takes a tuner and balun to
make it work, and if this was included in the rig and was automatic, it
would be ideal.

73, Steve KB9X

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Old March 5th 07, 03:20 PM posted to rec.radio.amateur.moderated
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Default Tube equipment question

wrote:
On Mar 5, 3:26 am, Mike Coslo wrote:
wrote groups.com:



The simplicity was what attracted me to them. No filters, nonotch,
no pbt, no RIT, no - well you get it.


Note that the
75 meter one stops at 3.8 MHz. Heath figured that by
simplifying the output pi network to the most extreme degree,
they could save a few dollars. Coming up with a 50 ohm
antenna was the ham's problem.

The 75 meter rig I have tunes to 4 MHz. It's also a HW22a, probably a
later mod. But all that simplicity is a good thing for a lad raised
mostly on integrated circuits! 8^)


The 75m transceiver is the HW-12A. It runs 3.8-4.0 MHz. That's all
the phone band there was back when the rig was produced.


Thanks for the correction Dave. I should have looked at the back of the
unit when I was composing my email



There's a
mod in one of the mags--CQ, I think--that puts in a fixed silver mica
cap with a little trimmer cap in parallel for making the thing work on
both 3.8-4.0 and 3.7-3.9 MHz at the flip of a mini-toggle switch.
That'd give you a bit more room to roam.


Now there is serendipity for ya! I was trying to align the thing, and
having some trouble with the top end. And the unit had this extra switch
on the front. Since I couldn't find the schematic for the "a" version, I
wasn't sure if that switch was part of th ea version or not. Preliminary
looks made me think that it might have been something to lower the
frequency down to the CW portion of the band. But it looks as if my rig
has that mod .


In it's era, the TS-830 was somewhat of a DXer's and contester's dream
machine.
That receiver has an extra filter slot for cascading filters. One can
still buy after market filters for it.


I can believe that it was very popular. The hybrid concept is
interesting. I especially like that you can turn the tubes off if you
just want to listen.

- 73 de Mike KB3EIA -

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Old March 6th 07, 12:22 AM posted to rec.radio.amateur.moderated
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Default Tube equipment question

From: Mike Coslo on Sun 4 Mar 2007 22:56

" wrote:


Besides old ARRL Handbooks prior to the 1970s, I'd suggest
finding the site that has digitized copies of GE Ham News.
Those were (bi-monthly?) hand-outs by GE to push their
tubes (naturally) but they contained lots of different ham
projects (using tubes, of course).


Got it! Thanks a lot Len - I googled them up, and have enough reading
material to keep me busy for a while.

the site is: http://bama.sbc.edu/ge_ham_news.htm


Thanks for the reminder on BAMA contents. BAMA has more
than just old tube equipment manuals. :-) Good site!

On the general subject of tube PA matching to load, some
remarks:

The automatic antenna tuner might have its beginning at
Collins Radio of the 1950s decade. Reference is the T-195
transmitter, part of a set that used the special version
of the R-390 series called the R-392, designed and built
for the USMC, first fielded in 1955, intended to be Jeep
mounted. The basic whip antenna matching was a servoed
single variable L and a single variable C to a conventional
PA output tank...so-called Ell-network, switchable to
the four possible L-C connection possibilities. On an
Army demo in late 1955, I was most impressed when the
demonstrating officer simply removed half of a whip
section (!), hit the tune function, and the servo
system re-tuned to this new antenna impedance in
seconds. :-)

Warren Bruene must have had a hand in that Autotune
labeled antenna matcher because it has the first instance
I've seen for the "Bruene detector" in the transmission
line to get both amplitude and phase of the RF. Slight
variations of that exist today, generally with a toroid
for current output and a small capacitor for voltage
output, both combined into dual diode detectors. Today's
antenna auto-tuning subsystems use binary-progression
switched single inductors and single capacitors with the
servo system basically a microcontroller plus small
frequency counter (sometimes) that can determine which
L or C to switch and remember the frequency and setting.
SGC (Stoner Goral Company) in the Puget Sound area of
Washington state has at least three models for both
maritime and amateur radio HF use. The Big3 (Icom,
Yaesu, Kenwood) have them, either built-in or as out-
board boxes. Several independent USA companies have
them.

ALL (no exceptions) antenna tuners have limits on
their impedance matching capabilities, whether "Pi-L"
output tanks or big boatanchor style structures
that look very impressive. There are few overall
advantages in any configuration with the possible
exception of Simplicity of the single L, single C
variety now common to today's autotuning matchers.
ALL, even the popular Pi-network, have limits that
can be proven mathematically; if the math doesn't
fit, no amount of publicity or historical references
will make it fit better.

If you or anyone else would like an algebraic-only
math explanation of the four combinations of single
L and C matching combinations...with their limits of
load impedance variation, I'll be happy to forward
them by e-mail attachments. No binary files here
and the equations, figures are better shown in the
PDF format.

73,

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Old March 6th 07, 02:30 AM posted to rec.radio.amateur.moderated
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Default Tube equipment question

On Mar 4, 10:56 pm, Mike Coslo wrote:

the site is:http://bama.sbc.edu/ge_ham_news.htm

Mike,

If you like the BoatAnchor Manual Archive, you
may be interested in these sites. Lots of
downloadable manuals and data:

First is Pete Millett's book site:

http://www.pmillett.com/tecnical_books_online.htm

Has some incredible stuff, like complete ARRL and
Radio Handbooks, Radiotron Designer's Handbook,
Reference Data for Radio Engineers, and much more.
All in PDF.

CAUTION! Some files are quite large, and will take a long
time to download via dialup. One trick I have used is to set up
a dialup download late at night, hit the button and go to bed.

and tube data, from the RCA HB-3 books:

http://www.pmillett.com/hb-3_tube_manual.htm

arranged by inidvidual tube type, for easy download.


The Glowbugs website has lots of downloadable info:

http://www.mines.uidaho.edu/~glowbugs/index.html

including some good manuals and articles on WW2 military surplus:

http://www.mines.uidaho.edu/~glowbug...__Surplus.html

http://www.mines.uidaho.edu/~glowbugs/PDF%20files/

Some of these are quite large, too.


"Bunker of Doom" site with lots of stuff:

http://www.bunkerofdoom.com/

Tube manuals, for example.

Transformer catalogs and other data:

http://www.bunkerofdoom.com/xfm/index.html


Another good site:

http://www.antiqueradioarchives.com/archives_index.htm



73 de Jim, N2EY







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Old March 6th 07, 02:30 PM posted to rec.radio.amateur.moderated
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Default Tube equipment question

On Mar 5, 3:20 pm, Michael Coslo wrote:
wrote:
On Mar 5, 3:26 am, Mike Coslo wrote:


The 75m transceiver is the HW-12A. It runs 3.8-4.0 MHz. That's all
the phone band there was back when the rig was produced.


Thanks for the correction Dave. I should have looked at the back of the
unit when I was composing my email


Not a problem. I'm fairly familiar with the series since I ran them
mobile for a number of years.

There's a

mod in one of the mags--CQ, I think--that puts in a fixed silver mica
cap with a little trimmer cap in parallel for making the thing work on
both 3.8-4.0 and 3.7-3.9 MHz at the flip of a mini-toggle switch.
That'd give you a bit more room to roam.


Now there is serendipity for ya! I was trying to align the thing, and
having some trouble with the top end. And the unit had this extra switch
on the front. Since I couldn't find the schematic for the "a" version, I
wasn't sure if that switch was part of th ea version or not. Preliminary
looks made me think that it might have been something to lower the
frequency down to the CW portion of the band. But it looks as if my rig
has that mod .


If I run across the mod, I'll forward a scan of the information to
you. There was another easy mod which padded the carrier oscillator
frequency in order to roll off some of the annoying high frequency
hiss on receiver, while adding fullness to the transmitted audio. It
had the added benefit of more carrier output for tune up.
Your HW-12A may have that mod as well.

In it's era, the TS-830 was somewhat of a DXer's and contester's dream
machine.
That receiver has an extra filter slot for cascading filters. One can
still buy after market filters for it.


I can believe that it was very popular. The hybrid concept is
interesting. I especially like that you can turn the tubes off if you
just want to listen.


The '830 doesn't get points for being an early hybrid, but it does get
points for having that cascaded filter availability. The early
Hybrids were rigs like the Yaesu FT-101 and variants along with the
Kenwood TS-520 and TS-820. Drake used a hybrid design in the T4-XC/R4-
C transmitter/receiver pair but there was a mix of tubes/solid state
devices in the receiver. The Drake 2-C receiver might have been the
earliest hybrid design amateur receiver.

Dave K8MN

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Old March 6th 07, 09:30 PM posted to rec.radio.amateur.moderated
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Default Tube equipment question

wrote:


These conditions may be partially remedied by use of a balun
that can be switched to either 4:1 or 1:1 ratio, and by choosing
antenna and feedline combinations that don't result in extreme
values of shack-end impedance/reactance. But that reduces
the flexibility of the system.


True enough.

snip



You can read AG6K's article he

http://www.somis.org/bbat.html

and judge for yourself.


I have gathered the parts to make just that!. I'd have it up now, but I
switched to a coax fed antenna for a while, and built a more traditional
tuner. In the interim I went back to balanced line.


AG6K's approach used two ganged roller inductors and
a single variable capacitor, compared to most commercial
manual tuners that use two variable caps and a single variable
inductor. Because there are only two controls, remoting the
tuner is made easier.


Some day I'll report on how mine is doing. In the present situation I
don't need remote tuning, but will probably motorize the unit anyway.

- 73 de Mike KB3EIA -

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Old March 7th 07, 04:02 AM posted to rec.radio.amateur.moderated
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Default Tube equipment question

On Mar 6, 4:30?pm, Michael Coslo wrote:
wrote:


You can read AG6K's article he


http://www.somis.org/bbat.html


and judge for yourself.


I have gathered the parts to make just that!. I'd have it up now, but I
switched to a coax fed antenna for a while, and built a more traditional
tuner. In the interim I went back to balanced line.


The AG6K tuner can be used with balanced or unbalanced
line.

All you have to do to use it with an unbalanced line is to ground the
coax shield at the tuner end of the coax balun,
and use the "other side" to feed the ungrounded line. A
simple SPST switch of adequate ratings can do the job.

The AG6K tuner, as described, has adequate matching
range for most dipole-fed-with-balanced-line amateur
antennas. A little care in choosing the antenna and
feedline length can make the tuner's job a lot easier.

Reg Edwards' DIPOLE3 program can be a big help in
figuring out the shack-end impedance of various
antenna/transmission line combinations.

AG6K's approach used two ganged roller inductors and
a single variable capacitor, compared to most commercial
manual tuners that use two variable caps and a single variable
inductor. Because there are only two controls, remoting the
tuner is made easier.


Some day I'll report on how mine is doing. In the present situation I
don't need remote tuning, but will probably motorize the unit anyway.


Although not mentioned in the article, the roller inductors
could be replaced by a pair of tapped coils and a double-pole switch.
The tap positions would have to be found by
experiment, but could be made permanent once they were found. Tuner
adjustment could then consist of simply selecting the correct tap
postion with the switch, and
adjusting the variable capacitor for minimum SWR.

Automatic tuners are not new to amateur radio, btw.
An automatic balanced tuner was described in QST for July, 1952. It
would automatically retune itself within
an amateur band. Changing bands meant changing coils, but once that
was done the tuner would do the rest automatically.

73 de Jim, N2EY

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