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 42-345 Restoration/Repair
With regard to the speaker, unless the cone is so brittle that it crumbles as soon as you touch it I would try to repair...Arran — 04:07 AM
Philco 42-345 Restoration/Repair
That silver can capacitor is an aluminum electrolytic. You should replace it with an aluminum electrolytic with the valu...RodB — 11:46 PM
Philco 42-345 Restoration/Repair
Thank you Rodb and Gary for helping with clarification on these capacitors. Other than the Tiny 630volt one I'm not sure...osanders0311 — 10:17 PM
1949 Motorola 5A9M
Hello All; I found the CMB41L down in the basement, it is definitely a 1950-51 model, the capacitors have date codes ...Arran — 07:48 PM
Philco 42-345 Restoration/Repair
Hi, all the caps I order, other than the electrolytics, are of the 630V rating. No worries on it being too high, and no ...gary rabbitt — 05:46 PM
Philco 42-345 Restoration/Repair
Hi, there's a lot to consider when designing these circuits so you shouldn't have a lot of concern when replacing caps. ...RodB — 02:03 PM
Philco 42-345 Restoration/Repair
I have ordered and received new caps for this radio and hope I've ordered the correct ones. I tried matching them to the...osanders0311 — 11:35 AM
Philco newbie with P-1891-WA console questions
Hello Jeff , Far as the Electrolytic capacitors go here is a list of parts. that will work . I like using Nichicon and...radiorich — 09:50 PM
Philco newbie with P-1891-WA console questions
Well, I've been stumped at trying to get the first of 11 electrolytic capacitors. I got a schematic and have a list of t...Jeffcon — 07:54 PM
Model 80 Antenna Issue?
Thanks Gary and Rod.  I also found an article in the Philco Repair Bench under Service Hints and Tips, about installi...Hamilton — 12:32 PM

[-]
Who's Online
There are currently 398 online users. [Complete List]
» 2 Member(s) | 396 Guest(s)
AvatarAvatar

>