Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

The 39-116 project: the beginning
#9

I made up a SS 80 with a couple 2.5A 1KV diodes. That brought the B+ up to around 320, that helped.

I finally have the remote receiver working with good (I think) sensitivity. I can trigger the thyratron with a -34dB input to the terminals. It will stay triggered down to -41. It was tricky to get it right, as the impedances on the grids of the 87 and the 6J7 (I'm temporarily using a 6K7) seem to be quite high, and even my scope probe loads them to a point they won't properly tune. I ended up feeding a +10dB signal in and getting the thyratron to fire, then backing the level off till it extinguished. I then tuned the first stage until it fired again then backed the level off till it extinguished again. Lather/rinse/repeat until I found what appears to be the best gain.

Now the next fun part. The stepper does not work reliably. This could be because I'm not able to send it properly spaced pulses until I get the Mystery Control working. We shall see.

The final chassis issue I have not wanted to deal with because it's going to be a total PITA is the volume control. This one has issues. Toward the lower end, it acts like a typical old volume control with either dire need of cleaning or a completely worn out trace. The volume jumps around as well as the timbre and the amount of distortion. If I find a sweet spot where the thing makes proper contact, it sounds great, but in the meantime it crackles and just makes very unpleasant noise. Once it's past this bad spot on the way up, it works fine and sounds great (but loud!!) This one of course is far more problematic to clean because it moves so slowly as you run the motorized volume up and down. I shudder at the thought of having to replace that control...


Messages In This Thread
The 39-116 project: the beginning - by BrendaAnnD - 03-20-2015, 05:47 AM
RE: The 39-116 project: the beginning - by morzh - 03-20-2015, 10:39 AM
RE: The 39-116 project: the beginning - by morzh - 03-20-2015, 02:39 PM
RE: The 39-116 project: the beginning - by BrendaAnnD - 03-22-2015, 02:48 PM
RE: The 39-116 project: the beginning - by morzh - 03-28-2015, 11:54 AM
RE: The 39-116 project: the beginning - by morzh - 03-28-2015, 12:43 PM
RE: The 39-116 project: the beginning - by morzh - 03-29-2015, 11:04 AM
RE: The 39-116 project: the beginning - by morzh - 03-29-2015, 11:37 AM
RE: The 39-116 project: the beginning - by morzh - 04-15-2015, 09:39 AM
RE: The 39-116 project: the beginning - by morzh - 04-15-2015, 09:59 AM
RE: The 39-116 project: the beginning - by morzh - 04-16-2015, 05:11 PM
RE: The 39-116 project: the beginning - by murf - 04-19-2015, 05:49 PM
RE: The 39-116 project: the beginning - by Edisla - 10-24-2017, 03:55 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco P45-6365 Universal Transformer Instruction Manual
Can anyone guide me to where this may be found?GRG — 03:00 PM
54C Complete Teardown/Rebuild
I don't think that I have encountered a 12Z3 before, curious how it uses one of those but includes a #43, which is a 25 ...Arran — 02:17 PM
HiFi (Chifi) tube amp build - but my own design.
It's the other forum. I'm also in DIY, but mostly read there. Honestly, I kinda jumped into this without much thought to...TV MAN — 10:43 AM
Philco 71 Code 125
Hello,  I am in need of a schematic for this radio. Mine has the three separate circular tube shields and a shadow me...dconant — 08:06 AM
Stromberg Carlson 1500 Squeal
And life just keeps getting more complicated.dconant — 07:57 AM
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM
54C Complete Teardown/Rebuild
Richard, The Silvertone 2014 also is a transformerless set, so I am incorporating a 1:1 600 ohm audio isolation transfo...glyphmon — 11:37 PM
Preliminary work on wife's Silvertone 2014
Did an alignment today which was interesting.  IF alignment went great, almost all was already spot-on.  Adjusting on th...glyphmon — 11:35 PM

[-]
Who's Online
There are currently 2642 online users. [Complete List]
» 1 Member(s) | 2641 Guest(s)
Avatar

>