Hi every one, I'm new to this site, but have been reading post for a while. There are some very knowledgeable radio individuals on this site. I'm working on a 1938 philco model 84 - 4-tube cathedral type radio. I changed the electrolytic and checked all the tube. The radio only is able to pick one radio satiation. I'm just using a wire as an antenna, about six feet long attached to the tuning capacitor. I did changes some of the main resisters. This type of radio has about 4 block capacitors, which appear to be good. (I did bridge like value caps to the block) Does anyone on this fine board have any ideal why I can only get one station and where to look for the problem? Any help would be appreciated. Thanks in advance! Radio Jeff
Posts: 7,213
Threads: 266
Joined: Dec 2009
City: Roslyn Pa
Hi RadioJeff and Welcome!!!
I think the 84 would be 1936 or old as there is a 37-84 (1937) and it was drop from 1938 line. Any way the only way is get these regen/superhet working properly is Replace all of the paper caps inside the bakelite housings, Check all resistors and replace if they are more that 20% out of spec, and the tickler winding on the osc coil as they go open a lot. They are easy to rewind so that isn't the death nail to the set.
Report back with findings
& good luck
Terry
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
THANKS TERRY, FOR THE RESPONSE AND INFO. I WILL CHECK THE RESISTER AND START TO LOOK INTO REWINDING THE COIL. IT THERE A WAY TO CHECK THEM. IN THIS PARTICULAR RADIO THERE ARE 3.COILS ALSO CAN THE BLOCK CAPS BE BRIDGED WITH THE LIKE VALUE CAPS ON A PERMANENT BASES OR SHOULD I TAKE THEM APART. THANKS
JEFF
Posts: 2,128
Threads: 18
Joined: Oct 2008
City: Merrick, Long Island, NY
I think everyone will agree that you should never ever bridge old caps with new ones. Dig 'em out, replace with new ones.
Posts: 7,213
Threads: 266
Joined: Dec 2009
City: Roslyn Pa
"I WILL CHECK THE RESISTER AND START TO LOOK INTO REWINDING THE COIL. IS THERE A WAY TO CHECK THEM."
Yes there is.With the set off and unplugged find pin 5 of the #77 mixer tube. It will have a 6K resistor a cap connected to it. The other end of the 6K resistor is connected to the osc coil. Connect your ohm meter there at the coil and to chaiss ground. Should read just a few ohms. If not time to rewind.
Just for grins with the set unplugged turn the volume all the way up. Hook the ohm meter from the ANT post to the GND post. Again should read just a few ohms. If not time to rewind the antenna coil.
"IN THIS PARTICULAR RADIO THERE ARE 3.COILS"
Correct. One is the Antenna coil (closest the the ANT post) one is the oscillator coil (The middle one) and one is the IF transformer.(The last one)
"CAN THE BLOCK CAPS BE BRIDGED WITH THE LIKE VALUE CAPS"
NO. The only thing bridging a cap a cross another cap is going to do add more capacity to that circuit. It does NOT affect the circuit if the original cap is leaky. It will not block any voltage that may be coming though a bad cap. Dig out the old and put in the new!!as codefox sez.
Terry
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
