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!!

 

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