The PHILCO Phorum

I just wanted to pass along a little something I discovered while working on a couple model 80's. After cleaning up and recapping/recarbing I was able to get them working ok but not great. They were not very stable and just about every time I turned one on I would have to readjust the feedback or the oscillator would quit working. So on one of them I implemented all of the posted upgrades, tried baking the oscillator coil and there was some improvement for sure but still not what I would expect. I struggled for some time with them without much success. 
What I ended up finding was on the sides of the tuning capacitor there are a couple screws that hold things together and the wires attach at this point as well. They were not very tight and there was a slight amount of oxidation on the small plates the wires solder onto. I cleaned up the plates and tightened the screws and now both sets work perfectly. The one set has all of its original value resistors and capacitors ie none of the posted upgrades and it works perfectly with no issues at all. Oscillator is rock solid and I was able to get a very good alignment that seems to be holding steady, my dial scale is reasonable accurate. I am really surprised at how good these little four tube sets work, all of my local stations come in loud and clear with just a short piece of antenna connected. 
So if you are having trouble with your model 80 this might be something to have a look at. Good luck and happy collecting!

Gregb

Greg,

I was excited to read your Philco Junior fix. I just finished a Philco Junior restoration and was not pleased with it's performance.
I checked the screws I assumed you were referring to (the screws at the trimmer caps). They were not very loose but I loosened them and sprayed with electrical contact cleaner before retightening based on your finding of oxidation. Long story short, the radio now has virtually no sensitivity picking up only two stations very weakly.

HELP - Was use of the contact cleaner a mistake? Could it have damaged the trimmer caps dielectric? Any ideas?

Thanks,
Don

> Was use of the contact cleaner a mistake? 

Probably not just make sure it has evaporated out (not wet anymore).

>Could it have damaged the trimmer caps dielectric?

They are mica so it's not likely.

GL

What Terry said, you will have wait for the cleaner to evaporate from between the trimmers. In this case I would apply the cleaner to a Q-tip and clean without spraying on the trimmers, I guess I should have mentioned that.


Gregb

There is a very good guide to tuner cleaning here:

http://audiokarma.org/forums/index.php?t...og.144163/

which goes into the method for cleaning and lubricating tuning capacitors.  The tuning capacitors on these Philco sets are old enough and corroded enough to look like something you may find in a bronze age archaeological dig.  This link is a sticky in the tuner section that has 300 posts in it.  Some are repeats of others and the devices described here are usually much newer and cleaner than an old Philco.

Don, if you loosened, cleaned and then retightened "trimmer" screws then you probably threw the alignment off that is unless I'm misunderstanding what screws you mean. That would explain the poor sensitivity!

Ron

Thanks for all the input, guys.

After letting the cleaner evaporate and realigning, the radio works like it did prior messing with these screws. However, the overall sensitivity is still less than I'd like. We live in an area of relatively weak radio reception but other radios with 5 or 6 tubes had no trouble strongly receiving many stations.

I'm guessing my radio's performance is probably what is to be expected with a 4 tube set and relatively weak signal strength. Am I missing anything? Does anyone know of any tricks to enhance the Model 80's performance?

Thank you, I appreciate all of your knowledge and willingness to share.

Don

Hi Don:
See the link below, this is the published improvements you can make to the model 80.


http://www.philcorepairbench.com/model-8...fications/

Gregb

Not only that, Don, but you should also replace the grid leak resistor which is mounted on top of the IF transformer with a new 2 meg, 1/2 watt resistor.

The best way I have found to replace this part is to clip the resistor leads up against the body of the resistor and then use those wire lead stubs to connect the new resistor. Trying to unsolder the original at the terminals on the IF transformer can damage the transformer.

Thanks to all who offered advice. I have made the suggested mods and see a definite improvement. Not only greater volume but also clearer reception.

Don

Ron, why the change to 2 megs on the resistor?  Is it worth taking my 80 apart to make the change?

You asked for mods which would improve the performance of the model 80. I don't care if you make the change or not.

..but it is an improvement.

Hey rfeenstra -

Look here for the answer to your question (fourth paragraph):

https://www.philcorepairbench.com/models...istor-mod/

My interpretation is if your 80 doesn't exhibit those symptoms, then there is probably no reason to take yours apart.

thanks! I did the other mods Ron suggested but somehow missed that page.