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: 1 Guest(s)
[-]
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 400 online users. [Complete List]
» 2 Member(s) | 398 Guest(s)
AvatarAvatar

>