Posts: 6
Threads: 2
Joined: Jan 2019
City: Ocala
State, Province, Country: Florida
I restored a Philco 80 recently that had been in an attic in New Jersey for a long while. The capacitors were all replaced and the power supply filters were replaced all caps are the value on diagram. The radio has reasonable sensitivity and picks up the same stations as the Philco 37-60 in my breakfast room. But this model 80 periodically breaks into motivating and squeals. The adjustment for feedback can sometimes stop it but then sensitivity is too low. This is an instability that seems to not affect the tube voltages. One thing that may be relevant is on the most powerful station the volume control can not go all the way to silent. The control is not open. Any suggestions from those who have a model 80?
Posts: 15,304
Threads: 532
Joined: Oct 2011
City: Jackson, NJ
I doubt model 80 could be aligned so that it is sensitive and doesn't squeal. Mine is borderline also.
Even the alignment doc talks about "birdies".
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Posts: 5,005
Threads: 267
Joined: Nov 2012
City: Bandon
State, Province, Country: OR
Welcome to the Phorum!
just in case you haven't seen them, the
Philco 80 Instruction booklet is in the Library.
Posts: 7,212
Threads: 266
Joined: Dec 2009
City: Roslyn Pa
Hi Jim and welcome,
I would check the 10k the 240k and the 1m resistor around the 36 detector tube. Measure the resistance from the grid cap to the chassis of the 36 should see abt 5m. If it's much higher it's time to pull the IF trans or drill out the rivets (3) on the shields and remove them to get the resistor. Do note that the plate voltage on the 36 det is abt 36v not 165v as listed on the diagram. There are two other possablties I can think of failing coils osc or ant, or a bad 36 tube.
Currently have an 80,81, bunch of 84's and 600. I Feel like I have fixed 100's of them vicariously on the net...
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
(This post was last modified: 01-18-2020, 11:15 PM by
Radioroslyn.)
Posts: 136
Threads: 27
Joined: Dec 2016
City: portland, OR
check the ground strap from the variable cap. I neglected to solder one back on a model 60. quite the mystery, with lots of squealing and motorboating [but little reception] until I happened to turn the radio around and saw the strap dangling.
page 4 on this site talks about "birdies."
https://www.tubesandmore.com/schematics/...on-corp/80
Posts: 6
Threads: 2
Joined: Jan 2019
City: Ocala
State, Province, Country: Florida
Gentlemen, thanks for the advice. Between working and the cold weather here in Florida, I have not been able to follow up. My work bench is in the corner of the garage. Normally this is OK but 35 degrees is too cold even for a displaced northerner.
I did try replacement type 36 tubes. The first set I got from the tube warehouse in Orlando were New old stock Tung Sol brand. The second batch was New old stock Phil co brand. The Phil co ones made it better than either the original tubes or the Tung Sol tubes.
I like Philco radios because like me they came from Philadelphia. And the tubes were made in Lansdale where I grew up.
I will respond when I get the chance to try out the tips you all send me.
Posts: 15,304
Threads: 532
Joined: Oct 2011
City: Jackson, NJ
Yep, mom said it was in low 40s at her place (Palm Coast).
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
(This post was last modified: 02-11-2020, 08:31 AM by
morzh.)
Posts: 6
Threads: 2
Joined: Jan 2019
City: Ocala
State, Province, Country: Florida
Hello again,
I had a chance to look at the values of the resistors around the type 36 second detector.
The 1 meg on the screen grid is 1.9 meg ohms instead of the 1 meg ohm standard value.
The 10K ohm resistor on the plate measures 13 K ohms.
the .24 meg ohm resistor connected to the 10K ohm plate resistor measures .61 meg ohms.
The .49 Meg ohm resistor on the grid 1 of the type 42 is open.
The second detector grid cap measures 4 meg vice the suggested 5 meg ohm value.
The tuning capacitor shell measures a very steady 200 ohms to ground.
And last and this is strange that I did catch it before. Someone in the past moved the antenna input to the wiper arm of the input sensitivity control and coil connection is now on the top of the sensitivity control, The control does measure 20K ohms.
I have some work to do on this beast from an attic in New Jersey.
Posts: 1,824
Threads: 114
Joined: Jul 2014
City: Sneedville, TN
Considering the values you stated, I would just replace all the resistors and be done with it, as well as correcting the wiring modification. This might well solve all of your problems.
Posts: 6
Threads: 2
Joined: Jan 2019
City: Ocala
State, Province, Country: Florida
Gentlemen, thanks for the advice. After a really busy life delay, all the resistors were replaced. The tuning capacitor was checked for ground resistance and an alignment was done. It is now working fine. The sensitivity is OK but not great and the birdies and motivating are gone. It sits on my desk in the office and I listen to Fox Sports 1. They have most Gator sports on live. I will say it was the most touchy radio to align. But it is a Phil co made in my home town. Thanks again.
Posts: 15,304
Threads: 532
Joined: Oct 2011
City: Jackson, NJ
Hey, you have to keep in mind it was $18.75 radio. It is a miracle it worked at all.
It was in essence "bait'n'switch" thing: come look at our "under $20" set and maybe you will like out $80 one instead.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
