Variable selectivity?
 

"gareth" wrote in message
...
"Michael Black" wrote in message
xample.org...
On Sun, 13 Oct 2013, gareth wrote:
Further information most welcome, thank-you
In the 1948 Radio handbook which I mentioned previously,
there are adverts
from a company by the name of Millen, and I assumed it
was the same guy
after he had left National.
Your comment about a phenolic intersperser is no doubt
some means of
isolating an
earthy contact?
It would be interesting to know from the Lamb patent
whether he proposed
therein the
technique of Single Signal Reception by the use of the
phasing control to
null
out the audio image, or whether this was something that
came about through
experience?
ONce again, "single signal selectivity" is credited to
the Lamb filter, everyone referencs that famous QST
article of his. You don't need the phasing control to
get the single signal selectivity.

Incorrect.

If the Xtal alone gave you single signal reception, then
there'd be no advantage
whatsoever in having the phasing control.

That the phasing control can be used to null out other
signals is the strong indication
that more than the one signal is getting through the Xtal.

Single Signal reception is the reference to the audio
image being phased out.


I have an RCA AR-88 receiver, this has a crystal filter
but does not make the phasing adjustment available although
there is one internally. The filter works quite well but the
lack of the phasing adjustment to null out heterodynes is a
distinct lack. In later versions of the receiver RCA did
bring the control out the front panel but, because its not a
balanced control, as is the Hammarlund and later Lamb
filter, it doesn't work nearly as well. I suspect RCA was
trying to avoid infringing the Lamb patent.
The original Lamb filter when set for high selectivity,
could cut out the audio image of a CW signal pretty well
but, of course, the phasing control could be set
specifically to null it out. Lamb wrote two or three
articles in QST in the early thirties about improving the
receivers available at the time and about single signal
reception.
You are right about the HRO not being the first receiver
with a crystal filter. I am not sure which was but an
earlier National receiver definitely had it as you point
out.
BTW, in searching for Lamb's patents earlier today I
came across one I didn't know about: its essentially a
mechanical filter using a rod with piezo electric drivers
and pickups. Lamb describes a variable bandwidth IF using
this filter for the medium wide band, a normal single
crystal filter for the narrow band and a conventional IF
transformer for the widest band. Curiously this patent is
assigned to RCA. I didn't note the patent number but all of
these can be found by searching Google Patents for James J.
Lamb.


--

--
Richard Knoppow
Los Angeles
WB6KBL

Variable selectivity?
 

"FranK Turner-Smith G3VKI" wrote
in message ...
"gareth" wrote in message
...
Incorrect.

Let's go Beanie, let's go.

Are you Cecil or Uncle Captain?


--

--
Richard Knoppow
Los Angeles
WB6KBL

Variable selectivity?
 

This is completely out of order, a posting about amateur radio on here,
almost unheard of!

"gareth" wrote in message ...

I wonder if anyone can offer a picture of the variable selectivity
arrangement of
the Eddystone EA12, which I believe was also used by some other
manufacturers?

This was the scheme whereby coupling between the primary and secondary of
IF
transformers was varied nechanically by distancing the two halves of the
transformer
from each other.

I have access to photos showing the operating levers, but what interests me
for
the moment is to have a peek, or peeks, inside the IF cans themselves.

Kenwood TS-130 Frequency warrble
 

At first, I wasn't sure if it was an amplitude or frequency "warble".
Finally decided it was frequency. A little ragged, but affected both receive
and transmit.
Not much, only a few htz, but ragged and disconcerting after so many years
of faithful service................


since I considder myself a a repairman, what do I do next? 30 or 40 years of
"freezemist" and " "heat gun" analysis, I still don't know my way around
this Kenwood TS-130. (my first transciever).

Replace all electrolytics and see what happens next?

HELP!

Old Chief Lynn, W7LTQ since 1948

Kenwood TS-130 Frequency warrble
 

coffelt2 wrote:
At first, I wasn't sure if it was an amplitude or frequency "warble".
Finally decided it was frequency. A little ragged, but affected both receive
and transmit.
Not much, only a few htz, but ragged and disconcerting after so many years
of faithful service................


since I considder myself a a repairman, what do I do next? 30 or 40 years of
"freezemist" and " "heat gun" analysis, I still don't know my way around
this Kenwood TS-130. (my first transciever).

Replace all electrolytics and see what happens next?

Is it warbling at 60 or 120 Hz? If it is, supply rails might be an issue.

But I'd first look at every internal oscillator on a scope and see which one
is unstable. Don't lock the scope to the input, lock it to line and adjust
the sweep by hand until the image on the scope stabilizes. You will see any
phase noise readily (assuming the scope timebase has no visible phase noise).

One of those oscillators is noisy. If they are _all_ noisy than it's time
to look at the supply.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Kenwood TS-130 Frequency warrble
 

On 14/01/14 09:58, coffelt2 wrote:
At first, I wasn't sure if it was an amplitude or frequency "warble".
Finally decided it was frequency. A little ragged, but affected both
receive and transmit.
Not much, only a few htz, but ragged and disconcerting after so many
years of faithful service................


since I considder myself a a repairman, what do I do next? 30 or 40
years of "freezemist" and " "heat gun" analysis, I still don't know my
way around this Kenwood TS-130. (my first transciever).

Replace all electrolytics and see what happens next?

HELP!

Old Chief Lynn, W7LTQ since 1948

Scott's suggestion is a good one but I'd also suggest you consider
checking that the PLL isn't simply on the limit of lock. It doesn't
sound like you've checked the radio over since new and, with the ageing
of components etc., it is quite possible things are not as they should be.

I've done a quick Google and there are copies of the Service Manual on
the internet and Kenwood manuals are pretty good. You should be able to
make the adjustments.

73
Brian
G8OSN/W8OSN

Kenwood TS-130 Frequency warrble
 

"Brian Reay" wrote in message
...

Scott's suggestion is a good one but I'd also suggest you consider
checking that the PLL isn't simply on the limit of lock. It doesn't sound
like you've checked the radio over since new and, with the ageing of
components etc., it is quite possible things are not as they should be.

I've done a quick Google and there are copies of the Service Manual on the
internet and Kenwood manuals are pretty good. You should be able to make
the adjustments.

73
Brian
M3OSN/G8OSN/W8OSN

Well done, Brian! See, you can make a positive and relevant contribution to
discussion, without gratuitous and somewhat infantile sneers, in this NG if
you really try.

Keep up the good work!

Kenwood TS-130 Frequency warrble
 

In article , Brian Reay wrote:

Scott's suggestion is a good one but I'd also suggest you consider
checking that the PLL isn't simply on the limit of lock. It doesn't
sound like you've checked the radio over since new and, with the ageing
of components etc., it is quite possible things are not as they should be.

I'd bet a nickel that this is precisely what is wrong... but you'll know
it when you see the PLL output it on the scope and it's bouncing around!

I've done a quick Google and there are copies of the Service Manual on
the internet and Kenwood manuals are pretty good. You should be able to
make the adjustments.

It's conceptually very different than working on an R-390 but to be honest
it's a whole lot easier.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Kenwood TS-130 Frequency warrble
 

On 14/01/14 21:10, Scott Dorsey wrote:
In article , Brian Reay wrote:

Scott's suggestion is a good one but I'd also suggest you consider
checking that the PLL isn't simply on the limit of lock. It doesn't
sound like you've checked the radio over since new and, with the ageing
of components etc., it is quite possible things are not as they should be.

I'd bet a nickel that this is precisely what is wrong...

I've seen it, and fixed it, numerous times. One of these things you see
when you've been around a bit.

Following the PPL set up procedure normally cures it for another decade
or more, I've never had one back again.

73
Brian
G8OSN/W8OSN

Kenwood TS-130 Frequency warrble
 

On Tue, 14 Jan 2014 15:48:24 -0000, "gareth"
wrote:
"Brian Reay" wrote in message
...

Scott's suggestion is a good one but I'd also suggest you
consider
checking that the PLL isn't simply on the limit of lock. It
doesn't sound
like you've checked the radio over since new and, with the ageing
of
components etc., it is quite possible things are not as they
should be.

I've done a quick Google and there are copies of the Service
Manual on the
internet and Kenwood manuals are pretty good. You should be able
to make
the adjustments.

73
Brian
M3OSN/G8OSN/W8OSN


Well done, Brian! See, you can make a positive and relevant
contribution to
discussion, without gratuitous and somewhat infantile sneers, in
this NG if
you really try.


Keep up the good work!

Ok Beanie, now its your turn.

--
73 de Frank Turner-Smith G3VKI - mine's a pint.