Posts: 451
Threads: 85
Joined: Nov 2011
City: Cumming, GA
Hi,
I have a Westinghouse H303P4 portable the prints here.
http://www.nostalgiaair.org/pagesbymodel...024160.pdf
I have recapped it and replaced the resistors that were out of tolerance. I had one bad tube the 1U5.
The If's were peaked (slugs) to 455kc no problem then I went next in the instructions to do the OSC (C8) at 1615kc feeding the signal into the tuning cap C5 and I cannot pick up a tone at all! The OSC coils read 12 and 2.6 ohms so they look to be ok. What am I missing? Thanks
Eric
Posts: 7,283
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
Hi,
Check the filament voltage across the 1R5 if it's just a little low it could stop the osc from working. If you have a variac you run the line voltage up a little to see if that gets in going.
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
Posts: 451
Threads: 85
Joined: Nov 2011
City: Cumming, GA
You might be on to something, I only get .980 volts on the 1R5 filament. Now I changed out the selenium rectifier and have a 100 ohm 5w ceramic for a dropping resistor if I raise the variac to it's max about 135 ac I get 150vdc (calls for 140v after the rectifier) between R16 and R3 seems like that should be enough but I only get 1.07vdc across pins 1&7.
Now I hooked up a power supply from AES I get 88vdc on the "B" battery and 4.5vdc on the "A" battery and I can adjust the "A" to get 1.4v on 1R5 but still nothing except static? where to go?
Posts: 7,283
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
Maybe a weak 1R5. Also check the connect to the loop ant.
R-20 is a voltage divider which drops the the B+ down to make the filament. Check it's value they can run hot and change value. If it's ok then play w/that resistor that is in series w/the si diode. Lower the value till the filament is @ 1.5v or so.
GL
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
Posts: 451
Threads: 85
Joined: Nov 2011
City: Cumming, GA
Swapped out the 1R5, Put a resistor in parallel and lowered the resistance and increased the filament volts to 1.35V. for some reason I can pick up a tone at 1400 and 2200kc on the signal gen but it will not adjust to the 1615kc with C8.
I re hooked up the DC power supply and I get 1.45V on the filament but reacts the same way. I'm going to pull and recheck the tubes and call it a day this tiny radio is wearing me out!
(This post was last modified: 07-17-2019, 08:34 AM by
Eric.)
Posts: 7,283
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
I just assumed that have the proper voltage or close to at the screen grid and plate of the 1R5. The voltage there is much more forgiving than the filament.
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
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