Metalwork - Lathe and Mill topics: January 2024

Sunday, 21 January 2024

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

I will keep this all in mind for sure 👍!!

On Jan 21, 2024, at 1:31 PM, Don Root VA3DRL <drootofallevil@teksavvy.com> wrote:

Robert , that method likely wont to much. I was mainly suggesting that many applications of tubes are not at one bias voltage. Variable Mu tubes are often have the bias controlled by the AVC. For the tube to do its job, it has to work as intended over a wide range of bias voltages/ gains.
Your testers likely test that the tube can provide lots of transcconductance[Gm] [gain, sort-of]. however when the bias is say minus 20 V, they don't bother to do another test the Gm ,, But they do/ can test for gas. It the tube is gassy it mucks-up the tube operation so it cant operate at small gain/ plate current so the tube can't throttle-back to low amplification.
I think I just saw that a 6SK7 has a normal Gm of 5000, but should throttle -back to only 10, [micro-Mhos] I think.
reading back; many 1930's gas tests were not very sensitive, but likely your testers have a good separate gas test using a marked "gas"switch. I wonder if you have tried that on the tube in question?

On Sat, Jan 20, 2024 at 07:56 AM, Robert Lonn WA6PHN wrote:

Not sure about that till I get further into this.. Sometimes I will turn the Bias up and down just to watch how the meter responds.. Not very scientific..
--
73 don va3drl

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert , that method likely wont to much. I was mainly suggesting that many applications of tubes are not at one bias voltage. Variable Mu tubes are often have the bias controlled by the AVC. For the tube to do its job, it has to work as intended over a wide range of bias voltages/ gains.
Your testers likely test that the tube can provide lots of transcconductance[Gm] [gain, sort-of]. however when the bias is say minus 20 V, they don't bother to do another test the Gm ,, But they do/ can test for gas. It the tube is gassy it mucks-up the tube operation so it cant operate at small gain/ plate current so the tube can't throttle-back to low amplification.
I think I just saw that a 6SK7 has a normal Gm of 5000, but should throttle -back to only 10, [micro-Mhos] I think.
reading back; many 1930's gas tests were not very sensitive, but likely your testers have a good separate gas test using a marked "gas"switch. I wonder if you have tried that on the tube in question?

On Sat, Jan 20, 2024 at 07:56 AM, Robert Lonn WA6PHN wrote:

Not sure about that till I get further into this.. Sometimes I will turn the Bias up and down just to watch how the meter responds.. Not very scientific..

--
73 don va3drl

_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

_._,_._,_

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

They did this so that there could be a number of different voltages used for the filament voltage for "portable" or mobile use.
You have to be very careful when wiring up the AC cord for Collins or you can easily wire it for the wrong voltage.
Also of note is often with extended use the alignment key on the 11 pin (IIRC) on the socket in the chassis can wear and the plug inserted incorrectly and zip go all of your tubes as well.
The 51S1 was uses extensively by the ASA (Army Security Agency) in the Vietnam era. It was used as a light receiver where the big boat anchors were a little cumbersome. Two were used in helicopters for RDF (and other unspecified uses).
When used with the Collins transmitters of the series they would allow almost full coverage of the range.
All of this is from a very poor memory of way back then.
JD
KE4MD

_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

_._,_._,_

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Not familiar with it at all, so this is just a guess. But perhaps to create a smaller magnetic filed around the filament leads? 1 amp vs 4 amps means much small magnetic field.

Again, just a guess

Will N4JBD

On 01/21/2024 11:58 AM CST Robert Lonn WA6PHN <roblonn@cox.net> wrote:

Not sure Electrically why Collins did this type of Filament set up, but it must have been for a very sound engineering reason..

This is a link to a short 1 minute Video of the filament circuit and 25.2 Volt AC power transformer. If your familiar as to why this was done this way, it would be appreciated to share your knowledge.. The KWM-2A has a somewhat similar setup for some of its tubes..

Robert WA6PHN

From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of Gary WB6OGD
Sent: Friday, January 19, 2024 8:58 AM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert,
Good advice.
I am no expert but I believe you can't rely too heavily on any tube tester. The actual circuit where the tube goes is the best tester.

I downloaded the 51s1 manual just to have a look. The BFO is one tube. I would try another, there are probably many types that could substitute
there if you don't have a good spare. I am thinking it maybe has a filament to cathode short or leakage of some kind that lets the AC filament signal onto
the BFO signal. But just a guess.
73,
Gary
WB6OGD

Grownups never understand anything by themselves and it is tiresome for children to be always and forever explaining things to them,

Antoine de Saint-Exupery in The Little Prince

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Spent an hour going through the 51S-1 Schematic to get myself familiar with the layout again.. Interesting is the 25.2 Volts AC used to feed all the Filaments in the 6 volt tubes.. You basically have 4 tubes in series, with several stages divided with dropping resistors and filter capacitors.. I did get some feedback early last year that someone who had the same issue found a cold soldering connection/Bad Capacitor on one of the filament of a tube..

Not sure Electrically why Collins did this type of Filament set up, but it must have been for a very sound engineering reason..

This is a link to a short 1 minute Video of the filament circuit and 25.2 Volt AC power transformer. If your familiar as to why this was done this way, it would be appreciated to share your knowledge.. The KWM-2A has a somewhat similar setup for some of its tubes..

https://www.youtube.com/watch?v=x4S52RDGNgM

Robert WA6PHN

From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of Gary WB6OGD
Sent: Friday, January 19, 2024 8:58 AM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert,
Good advice.
I am no expert but I believe you can't rely too heavily on any tube tester. The actual circuit where the tube goes is the best tester.

I downloaded the 51s1 manual just to have a look. The BFO is one tube. I would try another, there are probably many types that could substitute
there if you don't have a good spare. I am thinking it maybe has a filament to cathode short or leakage of some kind that lets the AC filament signal onto
the BFO signal. But just a guess.
73,
Gary
WB6OGD

Saturday, 20 January 2024

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Not sure about that till I get further into this.. Sometimes I will turn the Bias up and down just to watch how the meter responds.. Not very scientific..

BTW, I was watching a YouTube video on someone restoring a 1960's vintage tube table top AM radio..

He dripped some contact cleaner into the tube socket, OK nothing new there, but then he scrubbed the pin sockets with something??? I could not figure out what he was using?? So I asked him and then the light went off in my head… I think I will use these on the radio just to be sure everything is nice and clean..

Robert WA6PHN

https://www.walmart.com/ip/GUM-Proxabrush-Go-Betweens-Cleaners-Moderate-10-Count/740700598

From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of Don Root VA3DRL
Sent: Friday, January 19, 2024 10:53 PM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert , thanks for your words. I did read your stuff.

If they all test the tube at the same bias and get the same results, that is good.

Do any of them call for testing at a more negative bias as well ?? as a "normal" bias?

From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of Robert Lonn WA6PHN
Sent: Friday, January 19, 2024 10:43 PM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Don, as I mentioned in my other post, see below, I now have 4 tube testers and they are precision high end devices, hopefully they can expose any tube issues that might come up.. Robert WA6PHN

When I first did this I only had a B&K 747 tube checker, but last year I visited an estate sale and picked up 3 nice tube checkers…

A Heathkit TT-1, A Triplet 3444A and a Hickok 539C.. Good to be the first on site at 6:30am so I could get the pick of the litter.. Also grabbed all the Tubes, probably around 850 or so..

I think I will start with the 539C checker first and if anything seems strange I will check it on a different checker.. The TT-1 was calibrated by me, and it was very close, the 3444 and 539C tracked very close to the calibrated TT-1.. I did replace all the old capacitor in the Hickok and Triplet and a few in the Heathkit..

The Heathkit TT-1 has a built in " I think" a 5 KHz oscillator that they modulate on the grid of the tube.. ???? Maybe I should use that instead of the 539C, may reveal something with a questionable tube.. We will see how all that goes,, Let The FUN BEGIN, after all it is Ham Radio!!! J

From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of Don Root VA3DRL
Sent: Friday, January 19, 2024 7:13 PM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert and all

Re "I am no expert but I believe you can't rely too heavily on any tube tester. "

Well if it "reads bad" it likely is bad.

if it "reads good" it may well be good under the condition it is being tested at.

Most TTs measure Gm [where amplification is part of the intent in the tube.]

If you have a variable Mu tube you really want to know if it works properly with a small bias. But you want it to also work properly at a large negative bias

.. if you don't test it down there you might not know it has too hi a gm .. maybe that is where the gas messes things up like Jacques said.

I recently saw other postings somewhere the front end tube tested ok … but did similar things

.. but we need to get the books out on the details

From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of Gary WB6OGD
Sent: Friday, January 19, 2024 11:58 AM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

--
73 don va3drl

Friday, 19 January 2024

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert , thanks for your words. I did read your stuff.

If they all test the tube at the same bias and get the same results, that is good.

Do any of them call for testing at a more negative bias as well ?? as a "normal" bias?

Don, as I mentioned in my other post, see below, I now have 4 tube testers and they are precision high end devices, hopefully they can expose any tube issues that might come up.. Robert WA6PHN

When I first did this I only had a B&K 747 tube checker, but last year I visited an estate sale and picked up 3 nice tube checkers…

A Heathkit TT-1, A Triplet 3444A and a Hickok 539C.. Good to be the first on site at 6:30am so I could get the pick of the litter.. Also grabbed all the Tubes, probably around 850 or so..

Robert and all

Re "I am no expert but I believe you can't rely too heavily on any tube tester. "

Well if it "reads bad" it likely is bad.

if it "reads good" it may well be good under the condition it is being tested at.

Most TTs measure Gm [where amplification is part of the intent in the tube.]

If you have a variable Mu tube you really want to know if it works properly with a small bias. But you want it to also work properly at a large negative bias

.. if you don't test it down there you might not know it has too hi a gm .. maybe that is where the gas messes things up like Jacques said.

I recently saw other postings somewhere the front end tube tested ok … but did similar things

.. but we need to get the books out on the details

--
73 don va3drl

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Out of the thousands of tubes I have tested, it was a rare occasion I had to go into the circuit to find a bad tube. So unusual I cant remember the last time that happened with me. Very rare!

Lou WA5LOU

On Fri, Jan 19, 2024 at 10:51 PM Jim Shorney <jimNU0C@gmail.com> wrote:

Nevertheless, it remains a fact that a tube can be "good" on a tube tester and fail in circuit, and vise-versa. That is why it is said that the best test of a tube is the circuit that you want it to work in.

73

-Jim
NU0C

On Fri, 19 Jan 2024 22:19:09 -0500
"Lou WA5LOU" <loueverettsr@gmail.com> wrote:

> I've relied on mine for years and years and it has never failed me! I
> could not work on Tube rigs speedily without it!
>
> Lou WA5LOU
>
> On Fri, Jan 19, 2024 at 10:12 PM Don Root VA3DRL <
> drootofallevil@teksavvy.com> wrote:
>
> > Robert and all
> >
> > Re "I am no expert but I believe you can't rely too heavily on any tube
> > tester. "
> >
> >
> >
> > Well if it "reads bad" it likely *is bad. *
> >
> > if it "reads good" it may well be * good *under the condition it is
> > being tested at*. *
> >
> > Most TTs measure Gm [where amplification is part of the intent in the
> > tube.]
> >
> > If you have a variable Mu tube you really want to know if it works
> > properly with a small bias. But you want it to also work properly at a
> > large negative bias
> >
> > .. if you don't test it down there you might not know it has too hi a gm
> > .. maybe that is where the gas messes things up like Jacques said.
> >
> > I recently saw other postings somewhere the front end tube tested ok …
> > but did similar things
> >
> > .. but we need to get the books out on the details
> >
> >
> >
> >
> >
> >
> >
> > *From:* Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] *On
> > Behalf Of *Gary WB6OGD
> > *Sent:* Friday, January 19, 2024 11:58 AM
> > *To:* Amateur-repairs@groups.io
> > *Subject:* Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!
> >
> >
> >
> > Robert,
> > Good advice.
> > I am no expert but I believe you can't rely too heavily on any tube
> > tester. The actual circuit where the tube goes is the best tester.
> >
> > I downloaded the 51s1 manual just to have a look. The BFO is one tube. I
> > would try another, there are probably many types that could substitute
> > there if you don't have a good spare. I am thinking it maybe has a
> > filament to cathode short or leakage of some kind that lets the AC filament
> > signal onto
> > the BFO signal. But just a guess.
> > 73,
> > Gary
> > WB6OGD
> >
> >
> > --
> > 73 don va3drl
> >
> >
> >
>
>
>
>
>

--

73

-Jim
NU0C

_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

_._,_._,_

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

A general purpose tube tester is great for sorting out gross defects. But the devil is in the details, such as high frequency RF circuits and high impedance AVC/AGC.

An old school TV repairman taught me years ago that you don't toss a tube just because it tests low/weak/bad on a tester. If it works to spec in circuit it is "good".

73

-Jim
NU0C

On Fri, 19 Jan 2024 19:42:34 -0800
"Robert Lonn WA6PHN" <roblonn@cox.net> wrote:

> Don, as I mentioned in my other post, see below, I now have 4 tube testers and they are precision high end devices, hopefully they can expose any tube issues that might come up.. Robert WA6PHN

--

73

-Jim
NU0C

-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#91157): https://groups.io/g/Amateur-repairs/message/91157
Mute This Topic: https://groups.io/mt/103765884/693790
Group Owner: Amateur-repairs+owner@groups.io
Unsubscribe: https://groups.io/g/Amateur-repairs/leave/4530700/693790/458576413/xyzzy [jhjoshan@gmail.com]
-=-=-=-=-=-=-=-=-=-=-=-

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Nevertheless, it remains a fact that a tube can be "good" on a tube tester and fail in circuit, and vise-versa. That is why it is said that the best test of a tube is the circuit that you want it to work in.

73

-Jim
NU0C

On Fri, 19 Jan 2024 22:19:09 -0500
"Lou WA5LOU" <loueverettsr@gmail.com> wrote:

> I've relied on mine for years and years and it has never failed me! I
> could not work on Tube rigs speedily without it!
>
> Lou WA5LOU
>
> On Fri, Jan 19, 2024 at 10:12 PM Don Root VA3DRL <
> drootofallevil@teksavvy.com> wrote:
>
> > Robert and all
> >
> > Re "I am no expert but I believe you can't rely too heavily on any tube
> > tester. "
> >
> >
> >
> > Well if it "reads bad" it likely *is bad. *
> >
> > if it "reads good" it may well be * good *under the condition it is
> > being tested at*. *
> >
> > Most TTs measure Gm [where amplification is part of the intent in the
> > tube.]
> >
> > If you have a variable Mu tube you really want to know if it works
> > properly with a small bias. But you want it to also work properly at a
> > large negative bias
> >
> > .. if you don't test it down there you might not know it has too hi a gm
> > .. maybe that is where the gas messes things up like Jacques said.
> >
> > I recently saw other postings somewhere the front end tube tested ok …
> > but did similar things
> >
> > .. but we need to get the books out on the details
> >
> >
> >
> >
> >
> >
> >
> > *From:* Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] *On
> > Behalf Of *Gary WB6OGD
> > *Sent:* Friday, January 19, 2024 11:58 AM
> > *To:* Amateur-repairs@groups.io
> > *Subject:* Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!
> >
> >
> >
> > Robert,
> > Good advice.
> > I am no expert but I believe you can't rely too heavily on any tube
> > tester. The actual circuit where the tube goes is the best tester.
> >
> > I downloaded the 51s1 manual just to have a look. The BFO is one tube. I
> > would try another, there are probably many types that could substitute
> > there if you don't have a good spare. I am thinking it maybe has a
> > filament to cathode short or leakage of some kind that lets the AC filament
> > signal onto
> > the BFO signal. But just a guess.
> > 73,
> > Gary
> > WB6OGD
> >
> >
> > --
> > 73 don va3drl
> >
> >
> >
>
>
>
>
>

--

73

-Jim
NU0C

-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#91156): https://groups.io/g/Amateur-repairs/message/91156
Mute This Topic: https://groups.io/mt/103765884/693790
Group Owner: Amateur-repairs+owner@groups.io
Unsubscribe: https://groups.io/g/Amateur-repairs/leave/4530700/693790/458576413/xyzzy [jhjoshan@gmail.com]
-=-=-=-=-=-=-=-=-=-=-=-

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Don, as I mentioned in my other post, see below, I now have 4 tube testers and they are precision high end devices, hopefully they can expose any tube issues that might come up.. Robert WA6PHN

When I first did this I only had a B&K 747 tube checker, but last year I visited an estate sale and picked up 3 nice tube checkers…

A Heathkit TT-1, A Triplet 3444A and a Hickok 539C.. Good to be the first on site at 6:30am so I could get the pick of the litter.. Also grabbed all the Tubes, probably around 850 or so..

Robert and all

Re "I am no expert but I believe you can't rely too heavily on any tube tester. "

Well if it "reads bad" it likely is bad.

if it "reads good" it may well be good under the condition it is being tested at.

Most TTs measure Gm [where amplification is part of the intent in the tube.]

If you have a variable Mu tube you really want to know if it works properly with a small bias. But you want it to also work properly at a large negative bias

.. if you don't test it down there you might not know it has too hi a gm .. maybe that is where the gas messes things up like Jacques said.

I recently saw other postings somewhere the front end tube tested ok … but did similar things

.. but we need to get the books out on the details

--
73 don va3drl

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

I've relied on mine for years and years and it has never failed me! I could not work on Tube rigs speedily without it!

Lou WA5LOU

On Fri, Jan 19, 2024 at 10:12 PM Don Root VA3DRL <drootofallevil@teksavvy.com> wrote:

Robert and all
Re   "I am no expert but I believe you can't rely too heavily on any tube tester. "

Well if it "reads bad" it likely is bad.
if it "reads good" it may well be   good under the condition it is being tested at.
Most TTs measure Gm [where amplification is part of the intent in the tube.]
If you have a variable Mu tube you really want to know if it works properly with a small bias. But you want it to also work properly at a large negative bias
.. if you don't test it down there   you might not know it has too hi a gm .. maybe that is where the gas messes things up like Jacques said.
I recently saw other postings somewhere the front end tube tested ok … but did similar things
.. but we need to get the books out on the details

From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of Gary WB6OGD
Sent: Friday, January 19, 2024 11:58 AM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert,
Good advice.
I am no expert but I believe you can't rely too heavily on any tube tester. The actual circuit where the tube goes is the best tester.

I downloaded the 51s1 manual just to have a look. The BFO is one tube. I would try another, there are probably many types that could substitute
there if you don't have a good spare. I am thinking it maybe has a filament to cathode short or leakage of some kind that lets the AC filament signal onto
the BFO signal. But just a guess.
73,
Gary
WB6OGD

--
73 don va3drl

_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

_._,_._,_

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert and all

Re "I am no expert but I believe you can't rely too heavily on any tube tester. "

Well if it "reads bad" it likely is bad.

if it "reads good" it may well be good under the condition it is being tested at.

Most TTs measure Gm [where amplification is part of the intent in the tube.]

If you have a variable Mu tube you really want to know if it works properly with a small bias. But you want it to also work properly at a large negative bias

.. if you don't test it down there you might not know it has too hi a gm .. maybe that is where the gas messes things up like Jacques said.

I recently saw other postings somewhere the front end tube tested ok … but did similar things

.. but we need to get the books out on the details

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Thanks Gary,, will need my son to come over and help me move the Eddystone off the bench, BUT!!!!! Saturday and Sunday are Football Days, love the sport since I was 10 years old.. My wife is a big Dallas fan so that did not go over to good… Ever since the Chargers moved from San Diego to LA, I gave up on them a long time ago.. Only one more to Go Down, Chiefs!! Then we have some new blood in the Super Bowl..

I also love to see the underdog beat up on the So Called, Best Team… As they say, "On Any Given Sunday" J

Robert WA6PHN

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

_._,_._,_

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Thanks folks for the feedback.. I documented some tips and tricks for MYSELF several years back on what to do if things become strange, complicated or you want to bang your head on the wall… One was to go back and start everything over again troubleshooting from the beginning double checking what you think you just did! Since it has been a while I decided that I should start by checking all the tubes again.

When I first did this I only had a B&K 747 tube checker, but last year I visited an estate sale and picked up 3 nice tube checkers…

A Heathkit TT-1, A Triplet 3444A and a Hickok 539C.. Good be the first on site at 6:30am so I could get the pick of the litter.. Also grabbed all the Tubes, probably around 850 or so..

I am in the middle of finishing up a sensitivity issue on 2 bands only on my recently acquired Eddystone 880/2, all 90 lbs. worth,, and at age 75 my son needs to help me move it! BTW, the Hammarlund HRO-500 seen in the video had a PLL issue as expected, and replacing all 18 capacitors restored it to full operation.

I think the hardest part is changing the dial lamps.. What were those engineers thinking, unlike the Eddystone where everything is designed to fix stuff…

Robert WA6PHN

From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of James Amos
Sent: Friday, January 19, 2024 5:02 AM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Hi Robert,

I listened to your Youtube video, thanks for sharing that. Also, great to hear that you've already checked the components that are particular to the SSB/CW demodulation. What I think I hear in your video is that the SSB signals are not being correctly placed in the filter passband. I would check the frequency of the BFO if you can. Any offset in the BFO frequency can be heard directly in the audio. I also hear the noise Gary is hearing and agree with his power supply comments. I would also suspect the BFO power supply, tube, or biasing components.

Given that the radio is otherwise working, I'd swap the tube out first. The manual I downloaded also has a voltage and resistance chart starting on page 4-2. I would do a quick check against that. One nice thing about tubes is that they are high impedance powered down, so the resistance values are based solely on the passive components. But, this is also an old radio, so we also need to worry about aged components.

Keep us up to date on your progress!
73's Jim N8CAH

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

_._,_._,_

Thursday, 18 January 2024

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert,

That sounds like a hum or buzz.

Even though the caps have been changed, I'd scope the power supply to the BFO especially.

Scope the BFO signal or listen to it on another receiver.

Or try a new BFO tube.

73,

Gary

WB6OGD

On 01/18/2024 9:06 PM PST Jacques Fortin <jacques.f@videotron.ca> wrote:

Robert,

It seems to me that your AGC system is in trouble in this 51S-1.

I once had a similar trouble in my own 1967 WE when I bought it.

What I found suspect is that your S meter pegs to the max at all times (or almost).

In my own 51S-1, I found that the root cause of the problem was the 6DC6 RF amp tube: despite it tested good on a tube tester, internal leakage (gas ?) prevented the AGC line to go negative enough to control the receiver gain and everything received in SSB mode sounded as yours.

It take me two full weeks to finally find it !

I just swapped an other NOS tube and all became OK.

That could be the AGC line capacitors also causing this if they are still the original ones (leakage…).

You need to probe the AGC line when it is working.

Keep investigating !

73, Jacques, VE2JFE in Montreal

De : Amateur-repairs@groups.io <Amateur-repairs@groups.io> De la part de Robert Lonn WA6PHN
Envoyé : 18 janvier 2024 22:34
À : Amateur-repairs@groups.io
Objet : Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Thanks Jim, Well everything you mentioned has already been checked, Even though the diodes of the bridge were good, I replaced all of them and before I installed then I verified them on my curve tracer. Resistors are all close to specification, All electrolytic were replaced, and checked before I installed them. I reviewed the schematic again to be sure I understand what is going on.

I have worked on JRC, Hallicrafters, Eddystone and other tube radios and was always able to figure it out and get them working. The owner was aware of the issue with the radio, he never tried to fix it other than changing some tubes…

He said give me $100 and the radio is yours… Naturally I jumped on that deal back in Late 2021…

I did get advice last year that the person had the same issue. It was related to a bad filter capacitor that filters several filaments on several tubes… But that lead to a dead end as well…

This is a link to a YouTube video of the problem with the radio, when I switch to 40 meters into the video… Hope the link comes through…

https://www.youtube.com/watch?v=v593yNskhO4

Robert WA6PHN

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Robert,

It seems to me that your AGC system is in trouble in this 51S-1.

I once had a similar trouble in my own 1967 WE when I bought it.

What I found suspect is that your S meter pegs to the max at all times (or almost).

In my own 51S-1, I found that the root cause of the problem was the 6DC6 RF amp tube: despite it tested good on a tube tester, internal leakage (gas ?) prevented the AGC line to go negative enough to control the receiver gain and everything received in SSB mode sounded as yours.

It take me two full weeks to finally find it !

I just swapped an other NOS tube and all became OK.

That could be the AGC line capacitors also causing this if they are still the original ones (leakage…).

You need to probe the AGC line when it is working.

Keep investigating !

73, Jacques, VE2JFE in Montreal

De : Amateur-repairs@groups.io <Amateur-repairs@groups.io> De la part de Robert Lonn WA6PHN
Envoyé : 18 janvier 2024 22:34
À : Amateur-repairs@groups.io
Objet : Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Thanks Jim, Well everything you mentioned has already been checked, Even though the diodes of the bridge were good, I replaced all of them and before I installed then I verified them on my curve tracer. Resistors are all close to specification, All electrolytic were replaced, and checked before I installed them. I reviewed the schematic again to be sure I understand what is going on.

I have worked on JRC, Hallicrafters, Eddystone and other tube radios and was always able to figure it out and get them working. The owner was aware of the issue with the radio, he never tried to fix it other than changing some tubes…

He said give me $100 and the radio is yours… Naturally I jumped on that deal back in Late 2021…

I did get advice last year that the person had the same issue. It was related to a bad filter capacitor that filters several filaments on several tubes… But that lead to a dead end as well…

This is a link to a YouTube video of the problem with the radio, when I switch to 40 meters into the video… Hope the link comes through…

https://www.youtube.com/watch?v=v593yNskhO4

Robert WA6PHN

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

He said give me $100 and the radio is yours… Naturally I jumped on that deal back in Late 2021…

I did get advice last year that the person had the same issue. It was related to a bad filter capacitor that filters several filaments on several tubes… But that lead to a dead end as well…

This is a link to a YouTube video of the problem with the radio, when I switch to 40 meters into the video… Hope the link comes through…

https://www.youtube.com/watch?v=v593yNskhO4

Robert WA6PHN

From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of James Amos
Sent: Thursday, January 18, 2024 1:36 PM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

If you are seeing distortion in CW/SSB and not AM, I would start with circuitry that is used in CW/SSB, and not AM. This includes the product detector, and the SSB/CW preamp. The SSB/CW preamp in particular has some high value resistors that drop 140V down to levels suitable for the 2N2222A preamp transistor. So, start with the 140V supply and work you way in from there. The number of parts to check in this area of circuitry is relatively low, so look for heat damage. The resistors are 10% carbon comp and those can age and change value over the years. There's also a electrolytic emitter bypass capacitor on the SSB/CW AF Preamp that should be checked, that and other electrolytic caps are probably starting to age. As pointed out earlier, from a signal point of view this can also be checked with a simple RF carrier injected at the antenna then tuned for the correct sideband reception. You should be able to see a sine wave all the way through the receiver chain which you can also check for where the distortion is introduced.

Also, the signal for AGC is sampled ahead of the last IF Amplifier, so there is no AGC voltages that are part of the product detector or SSB/CW preamp circuitry.

I hope this helps,
Jim N8CAH

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

Excellent educated advice Jim. It appears you are even familiar with the radio in question here.
I have been reading this thread with interest but have come to the conclusion that the OP is pretty inexperienced at radio repair.
What he was asking for is not what he really needs.
If he follows your advice, he has a chance to fix his problem.
Thanks and 73,
Gary
WB6OGD

_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

_._,_._,_

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

_._,_._,_

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

On 1/18/2024 12:25, Robin Midgett wrote:
> If you read through the previous responses, you'll see that he has a
> solution, no parts necessary since he has what's required.

Win-win.

Back to my time machine idea so I can catch up on messages faster.

Kurt

-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#91137): https://groups.io/g/Amateur-repairs/message/91137
Mute This Topic: https://groups.io/mt/103765884/693790
Group Owner: Amateur-repairs+owner@groups.io
Unsubscribe: https://groups.io/g/Amateur-repairs/leave/4530700/693790/458576413/xyzzy [jhjoshan@gmail.com]
-=-=-=-=-=-=-=-=-=-=-=-

[Amateur-repairs] Creating a LSB and USB Test Signal!!

"You can generate some DSB with, but to have only the LSB or USB, you
still need a filter (mechanical, crystal, ceramic, whatever...)."

So, it meets the requirements, "Creating a LSB and USB Test Signal",
with some additional parts, which I think the chip needs anyway, to
function...

On the other hand, a DSB generator allows one to only switch the
receiver between modes, not the general purpose test generator, as well.

Kurt

-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#91136): https://groups.io/g/Amateur-repairs/message/91136
Mute This Topic: https://groups.io/mt/103765884/693790
Group Owner: Amateur-repairs+owner@groups.io
Unsubscribe: https://groups.io/g/Amateur-repairs/leave/4530700/693790/458576413/xyzzy [jhjoshan@gmail.com]
-=-=-=-=-=-=-=-=-=-=-=-

Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!

If you read through the previous responses, you'll see that he has a solution, no parts necessary since he has what's required.

Thanks,

Robin Midgett K4IDC

On Thu, Jan 18, 2024 at 12:18 PM Facility 406 <facility_406@bruteforcedevelopment.com> wrote:

On 1/16/2024 08:37, Robert Lonn WA6PHN wrote:
> I have been working on a receiver that has a USB and LSB problem. I am
> using my Icom IC-705 radio as a test source. I want to replace this with
> something that will generate a USB or LSB Test Signal continuously so I
> can inject it into the receiver and then check stages of the radio etc. etc.
> I have most test equipment available but was wondering if anyone has
> done this and what type of test equipment setup they have used..
> Thanks in advance for your help...

Are you looking to buy something, or build something? There are several
LSB/USB generator 14 pic ICs out there that require very few parts.
Here is one I came across this morning:

https://www.jameco.com/z/MC1496P-Major-Brands-IC-MC1496P-Balanced-Modulator-and-Demodulator-14-pin-DIP_23211.html

Kurt

_._,_._,_

Groups.io Links:

You receive all messages sent to this group.

_._,_._,_