I re-capped this Philco 40-150 code 121 and replaced resistors that were questionable. I also replaced some rubber insulated wires that were dried and cracked. I powered up the radio with my variac and it works okay. The speaker was rattling so bad I sent it out for re-cone. I'd like to do some more power on testing but I don't have the speaker. Is it okay to power this set up without the speaker attached? I've always thought that was a no-no.
Pepperoni
Its not a no-no. As long as you know what you are doing.
You can power up the radio but there will be no B+ voltage present on the tubes other than the rectifier.
The speaker field coil acts as a filter choke for the power supply. Without it connected no DC voltage will pass from the rectifier tube and first filter cap to the rest of the radio circuitry.
Hi Pepperoni long time no post!
I'd say generally the answer is no it is not a good idea. You can't do any voltage measurements because there is little or no load on the power supply and as Mike mentioned the only place you'll from any HV is near the 84 tube no where else. This can cause #61 to short from exceeding it's maximum voltage rating. It starts with a hiss then PPPPPOOOOOWWWWWW!!!!
Good to hear from you.
This is why I use 500V caps in these places.
(12-31-2016, 11:17 PM)morzh Wrote: [ -> ]This is why I use 500V caps in these places.
I'm cheep I just leave the spkr hooked up and use 450v jobs.
Thanks folks, It has been a while. I've slowed down on the radio work. Just getting a little older. I wanted to make sure I was doing this correctly. I'm also waiting for the good paperwork from Chuck. Now I'm waiting for the speaker so I can perform the voltage checks etc. I may be back with this radio. I powered it up after the re-cap and resistor checks and it wasn't working great. Reception wasn't great. I'll run it through the gauntlet of tests when I get that speaker. Thanks again.
Pepperoni
The speaker sounds normal now but I still had a low volume problem. The problems I have with radios are the ones that have been tinkered with by someone not knowing what they were doing. Both old filter caps were left in the circuit and the new ones were paralled with the old ones so I fixed that and for what ever reason someone had rewired the audio circuit. Put that back into the proper configuration and this radio sounds great.
Pepperoni
