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

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

37-116, Alignment of 18 MC band, LO instability
#1

I just completed my alignment of the 37-116. I thought I'd pass on my experience with an instability issue on the high freq band.

On the 18 MC band, I first attempted to follow the instructions for alignment by seeking the second peak on the 18 MC compensator (43D). It did not work. The local oscillator totally broke down and went crazy higher than 16 MC. At first I thought, maybe a bad component in the oscillator section, or a poorly dressed wire. But that was not it.

The problem was due to the setting of the low end of the band at 12 MC (43E). Since I did a major overhaul, the settings of the compensators was way out of wack. I found that I had to adjust the low end first, then set a mid range point at 15 MC, a point where the oscillator was still working. I then had to cycle back and forth several times, resetting the 12 MC and 15 MC until the adjustments stablilized (no changes needed). Then I could go high and adjust at 18 MC, which really did not need much change. Also, I did not have any problem with the other bands, nor the compensators for the antennae and RF sections.

This issue may not occur on a chassis that has not been "messed around with", or where the low end compensator was not modified.

John
#2

John - thanks for sharing. This info should come in handy for everyone.

--
Ron Ramirez
Ferdinand IN




Users browsing this thread:
[-]
Recent Posts
Philco model 38 code 121 not receiving signal.
Good news everyone! I think I have found everything I need for rewinding the antenna coil primary. I found some pla...Stormlord5500 — 09:40 AM
Philco Battery-WWII vintage
My younger sister went to SUNY Plattsburg NY, (BS, MS, RN) in the late 1970sabout 10 min from the Northern NY / Canada b...MrFixr55 — 07:59 AM
Philco Battery-WWII vintage
Hello Bob, What Amazing find! Sincerely Richardradiorich — 10:19 PM
Testing a speaker and output transformer Trutone A2-G
Hi Murf, Do this: Monitor between ground and one plate of the rectifier while playing the radio.  Do the same with ...MrFixr55 — 09:51 PM
Philco Battery-WWII vintage
Mike; I take it that Soviet cars did not come equipped with block heaters, hence the hot oil change? Where I lived in...Arran — 08:42 PM
Philco 42-345 Restoration/Repair
The more the better. (Within reasonable limits.) 2-5 times more is no problem in this case.Vlad95 — 03:50 PM
Philco 42-345 Restoration/Repair
Thanks, RodB and Vlad95, I was mainly trying to figure out this capacitor to locate a replacement, Vlad thank you for...osanders0311 — 03:44 PM
Testing a speaker and output transformer Trutone A2-G
Would an output transformer if weak, cause the problems I am seeing with lower B+ voltage? murfmurf — 01:22 PM
Testing a speaker and output transformer Trutone A2-G
Hello murf! I merged the threads. Please do not start new threads regarding the same radio. Take care, - GaryGarySP — 10:21 PM
Philco 42-345 Restoration/Repair
Regarding picture 5 on page 1 of this thread this capacitor is #40 on scematics diagram - 4mF+4mF. Black wire is "-...Vlad95 — 09:01 PM

[-]
Who's Online
There are currently 568 online users. [Complete List]
» 5 Member(s) | 563 Guest(s)
AvatarAvatarAvatarAvatar
Avatar

>