Alignment question - Printable Version
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Alignment question - thirtiesradio - 06-13-2013
I've finally gotten around to recapping my 37-670B. Looking over the schematics, the alignment looks abit complex on this set. It calls for a 350mmfd variable cap to be used for some of the alignment steps. I'm not sure I have a 350mmfd variable cap. I do have a 16B code 125 parts chassis with the variable caps still on it but the schematic doesn't list the values. Anyone have the values for the variable caps on this set?
RE: Alignment question - morzh - 06-14-2013
Use any variable cap that is within the reason. Or buy one. They are still being sold.
http://www.mouser.com/Passive-Components/Capacitors/Trimmer-Variable-Capacitors/_/N-5g94/
RE: Alignment question - thirtiesradio - 06-14-2013
Thank you! I didn't know they were still being sold. I did an internet search putting in 350mmfd and didn't find anything new that was being sold. I should have put in pf instead of mmfd
RE: Alignment question - morzh - 06-14-2013
They are called trimmer capacitor.
"trimmer" is used toward caps and resistors that are variable but are adjusted once and then stay in this position forever, unlike the true variable caps and resistors that are used for tuning / regulating. There is always need in them so in foreseeable future I don't think they are going to disappear, especially the thrim-pots.
Although there are varicaps (voltage controlled diodes that are used as trimmer/pullable caps) and digitally controlled trimpots which are actually microchips using MOSFETs and EEPROMs.
RE: Alignment question - thirtiesradio - 06-14-2013
Thank you Morzh!
RE: Alignment question - thirtiesradio - 06-17-2013
Well I aligned the radio twice. Found a trimmer that worked well for the 350pf. The radio is a decent performer. Better than most but not quite a 16B on standard broadcast. The 16B can bring in the faintest of signals. With the 37-670 you can hear them, but they drift/overlap with other weak stations. I did find it exellent and similar to the 16B in the shortwave bands. The 37-670 has a 8" speaker but to me sounds as good as a 16B with it's 10" speaker. I don't care for the "stepped" tone control but again, the sound is much better than most tabletops. Large and heavy but overall a very nice radio.