In a balanced push-pull Class C RF Final with plug-in coils, I've seen things done a couple of different ways.
One is, to split the B+ so that the potential is fed with the B&W HDVL jack-bar to the inside of the two coil's. The outside of the coils is then connected to the tubes. That's the way the home-brewed 250TH final I'm running was done, back in the mid '50's. There was also a couple of finger-stock pieces across the B&W butterfly tuning condenser to facilitate adding a vaccuum capacitor across it for allowing the circuit to resonate on a lower frequency (like 75, or 160m). I understand that the circuit would no longer be 'balanced' were that condition to occur. It would go back to being balanced if a pair of capacitors at half the required value were used, and where the two meet in the middle were tied to the stator of the Butterfly. THAT would keep it balanced. That's the reason for the split-stator capacitor across the final, now. But, that's not my question... I recently picked up another home-brew 250TH final that has had more RFI considerations involved in it's construction (than the one in current operation) as it was built sometime in the '60's. Screen and mesh aluminum, etc... It's nice and hopefully will keep me out of the neighbors TV's, microwaves, blenders, etc... (grin) But the plug in coil is what prompted me to this question: Is there a difference in feeding each of the inside sockets on the jack-bar with B+ from the top of the RF plate choke, vs having the two coils tied together, in the middle, and feeding B+ there? I understand that the potential is the same, but for the sake of having less stray capacitance and a 'cleaner' RF environment, which would be better, and please... tell me why? Thanks! -- 73 = Best Regards, -Geoff/W5OMR ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected] To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
