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

Philco 118 AVC Levels
#1

I have been chasing an AVC level issue on a 118 that I have completely recapped, resistors checked, tubes checked, and recalibrated. I find that the AVC level rarely gets above -3VDC and often will slip positive approx 1.5 VDC with no signal. I am looking for guidance as to whether a slight positive voltage is normal on the AVC bus with no signal and if not, suggestions as to where to begin my investigation. I thought AVC was always in the range of zero to negative values. Thanks for all of your help and guidance.

Gary
#2

Average AVC voltage is highly dependant on incomming signal level.
Weak signals will make the AVC hover near zero (max gain), like is should.

Since this set needs (and was designed for) an outdoor aerial of at least 30ft.,
I suggest trying that. Be sure to also use a lightning arrestor and install it properly.
Also very inportant is a good Ground on the set to a cold water pipe or ground rod.
This will also maximize your receiving signal strength.


Chuck
#3

Thanks for the response. I do have a 100 ft long wire on it although no ground. The receiver sounds good on AM and SW bands so I tend not to tamper any further. The shadow meter functions good for the most part but really only narrows up on really strong signals. I measured the AVC on the left side of the 2 meg resistor R15. I just wasn't sure that AVC should swing slightly positive like it does when it is at max gain.

This radio was quite the challenge but I am very pleased with its performance so far.

Gary
#4

Makes a lot of difference with what type of meter you are using. Going positive goes against the 'book' but I don't have enough knowledge to address this specific model.




Users browsing this thread:
[-]
Recent Posts
Philco 42-345 Restoration/Repair
So far still no broadcast, I am posting pictures of #14 Oscillator and also a resistor #27 which connects to an XXL tube...osanders0311 — 04:02 PM
Part numbers to model cross
I believe there is that document, and I think we might have it in the Library.morzh — 03:29 PM
Philco 42-345 Restoration/Repair
Ok MrFixr55,  I have tried the DeoxIT D5 on the band switch and even though it has relieved the tension I felt when turn...osanders0311 — 11:11 AM
Part numbers to model cross
Is there a reference somewhere where you can punch in Philco part numbers and see what models those parts were used in?Jim Dutridge — 10:17 AM
Philco 42-345 Restoration/Repair
Hi OSanders, Look carefully at the band switch. Turn it slowly and "wiggle" it around the desired band. ...MrFixr55 — 12:33 AM
5U4 vs 5Z4 tubes
I think that RCA and GE introduced metal tubes in the USA in 1936.  I don't know if they were being made by RCA, GE or b...MrFixr55 — 11:20 PM
Philco 42-345 Restoration/Repair
Vlad95, Thank you for the stringing guides and wow there are so manyosanders0311 — 06:01 PM
5U4 vs 5Z4 tubes
A pre war Hallicrafters, and an early one too, very nice! 1936 is pretty early for metal tubes too, which would explain ...Arran — 05:58 PM
Philco 42-345 Restoration/Repair
Thanks Rod, "When you hear the background hiss and no station it usually indicates that the oscillator quit" ...osanders0311 — 05:52 PM
Philco 42-345 Restoration/Repair
RodB :beerchug:Vlad95 — 10:22 AM

[-]
Who's Online
There are currently no members online.

>