The PHILCO Phorum

I hooked up a signal Generator and can follow the signal with a scope from the Ant hook up to the points marked with the tools.  I cannot get a signal to the second coil,  it goes into the capacitor but not out.   All the tubes test good, and I have not recapped it yet.   I was hoping to get it to work first,  I brought it upon a Variac and with the tubes in it draws about 1 amp.  Also on the schematic shows capacitors numbered 5,,10,,and 15 and I can't seem to find them.  I couldn't get the schematic to up load but it can be found here  http://www.philcoradio.com/tech/images/86.jpg   does anyone have a more detailed schematic?

Help the newbie please

Actually it is close, it should be I think 95 Watts so at @115V it is about 0.82A.
If your tube fully hot and this is what you get you are OK.

Welcome to the Phorum,
You might be wasting your time trying to get it to work before recapping. It only takes one cap shorted from age and the radio might not work. That is why most people consider recapping to be the 1st task in a restoration.

The missing caps might be in those bakelite blocks that are just above the three left-most coils in your picture. The caps you mention are connected to three of the coils in this set, so it is at least a possibility.

Second that, it is a wasteful and somewhat dangerous practice to tru to fix a radio before the recap (and resistors' check).

The caps in the Bakelite blocks are the 0.1uf with the 100 ohm resistors, number 7, 12, and 17. Just can't seem to locate 5. 10, and 15. I brought it up slow on the variac, and tested resistors and the capacitance of all the capacitors and they all are with in tolerance, and I know that doesn't make them good.

But shouldn't I get some kind of voltage or signal on both sides of the trimmer?

Something else to have a look at is the plate voltage on each of the RF amp tubes (pin 2). If you don't have any on any of the tube the RF coil primary is open (common problem with these older TRF set) Easy fix is to remove the coil from the chassis, remover the open winding (the smaller one) and rewind it with 50 turns of small magnet wire 32-40ga is fine not all that critical.

GL
Terry

ps Condensers 5,10,and 15 are the neutralizing condensers. I believe those are the one on the bottom of the chassis ( like where your file is next to) On the top of the chassis there are three or four trimmer for the tuning condenser ( to do the RF alignment).

Terry

I've never seen an 86 with bakelite block caps. They originally had tubular caps with a metal bracket to attach each cap to the chassis. Some serviceman must have added the bakelite blocks many decades ago.

Thanks for all the help,,,can you direct me to where I can find out what normal plate voltage would be on the RF tubes?

There are some voltages in the chart on this schematic. A little hard to read. For more readable info you could order a set of clear schematics from Chuck for only a few bucks.

Thanks klondike98

Yes, agree that the set should be gone through first. Make sure to check continuity in all the interstage transformers. 

Inject a modulated audio signal into the set. For a carrier use a value on the dial (~550 - 1500 KHz) Start at the gridcap of the detector tube and listen for the audio signal. Work back stage by stage and see if you still get audio. Where the audio disappears is where the problem lies. 

Sounds like an open xformr vice a bad neutrodyne cap.  

It's ALIVE,,,re-capped it replaced a couple # 26 tubes and I can pull one station. So now to align it, but it also says to neutralize it and tells how. Question is what is neutralizing?

Thanks everyone for all the help

https://en.m.wikipedia.org/wiki/Neutrodyne


In short, it was a way to cancel Miller capacitance to improve TRF sets' performance while the triode was the staple tube to be used. Went away with advent of the tetrode.

Thanks morzh