I had a Progressitron PTO in a 1962 Amelco R-390A/URR that was doing something
similar. Upon opening the PTO, I discovered one of those tiny npo caps had a
bad solder joint and would intermittently make contact. I cleaned up the solder
joint and made it good. It was one of the better PTO's that I had in the rest
of the R-390a/URR's and one R-390/URR. This was before I retired and makes that
event over 17 years ago.
Diddlesticks are great for tapping on microphonic tubes and places where you
can obviously detect the result of tapping, etc.
Les Locklear
Gulfport, Mississippi
Dx'ing since '57
----- Original Message -----
From: Jacques Fortin <jacque...@videotron.ca>
To: 'Bob Camp' <kb...@n1k.org>, 'Kevin Schuchmann' <kschuchm...@protonmail.com>
Cc: 'R390A' <r-390@mailman.qth.net>
Sent: 12/27/2024 4:06:04 PM
Subject: Re: [R-390] R-390 non A 12khz jump
________________________________________________________________________________
Not that easy to tap on something inside when the PTO is disassembled.
Unless it can be powered and the output monitored on a frequency counter at the
same time...
Good luck with that, anyways.
73, Jacques, VE2JFE in Montreal
-----Message d'origine-----
De : r-390-boun...@mailman.qth.net <r-390-boun...@mailman.qth.net> De la part
de Bob Camp
Envoyé : 27 décembre 2024 16:18
À : Kevin Schuchmann <kschuchm...@protonmail.com>
Cc : R390A <r-390@mailman.qth.net>
Objet : Re: [R-390] R-390 non A 12khz jump
Hi
Even a “tap with a pencil” sort of test might well identify the part that’s the
problem. I used to have a plexiglass rod in my tool kit for that sort of stuff.
Way safer than “tap with your finger” on tube gear. :)
Bob
On Dec 27, 2024, at 3:14 PM, Kevin Schuchmann via R-390 <r-
3...@mailman.qth.net> wrote:
Thanks to Tisha and Jacques,
It is a model 1 PTO and I have started the disassembly and will check
those capacitors closely.
Kevin
On Friday, December 27th, 2024 at 10:32 AM, Tisha Hayes
<tisha.ha...@gmail.com> wrote:
I would suspect a capacitor in the PTO circuitry that is on the verge
of failing.
A can of freeze spray may help you isolate the specific component;
Maybe even tapping on caps/resistors with the tip of an insulated
tool might help identify if there is a cracked component that works
differently.
The ballast tube would not be so 'precise' in causing a 12 KHz
offset. It is also a very simple thermonic device with an iron
filament in a hydrogen atmosphere that is just a current regulator.
Ms. Tisha Hayes, AA4HA
"We live in accordance with the flow of the times"
-Yoshio Mizuno
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