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OK I'm feeling good at that. Last night I removed tube sockets from blower box to rewire before I start troubleshooting my bang event. Hoping it's not the Tetrode Boards. This time I'm going for minimalist: As few wires as possible to reduce inductance & capacitance.

Thank you for Reply. "...all manner of sloppy design...''' sounds workable without but I already ordered a 1/2 dozen so I'll use them on the rebuild where I can.

Since my big bang event a few months ago (homebrew 4cx300a amp), I’m planning on taking advantage of the required disassembly / troubleshooting to replace the RF input (parallel inductance a’la Pride) rotary switch circuit with a 4 band relay board fashioned from an LPF kit. It should fit...

While I was doing my audio thing these past few months, I found a good YT repair site: Mend-it-Mark, from the UK. The vids allow viewers to watch his repair of assorted devices. He recently received a Copyright Strike for his repair video of a phono preamp that sells for £25k. What's more is...

FWIW, I have a copy of Lou's "Construction and Operation, Tri-Power Mobile Linear Amp" publication from 1979. It's written very well with pics & diagrams.

Goes way back

Me too but my DX-70T is unfixable due to the BPF filter board unavailability. I prepared to attempt replacing the SMT diodes (even purchased replacement diodes). After I saw how microscopic they were, it was obvious the required soldering work was beyond my skill set. Tweezers, an smt camera...

Lightly used EMS-14 desk mic. This is an Alinco mic not the look-alike clone. Purchased new in or about 2010 (I probably have original packaging and probably the Receipt too) been in the original box since for but 2 years use max. I do recall that the removable foam element cover (windscreen)...

Audio Note Kit 4 clone board 2x 12ax7 driving 2x 6sn7 driving 4x 6v6's into Ultra Linear OTP's for 16w clean sound. This is a temp layout to get it working. 12ax7's has separate DC Heater circuit & xfrmr

I'm going to take a guess by your handle here (Guitar_1999) that you are interested in audio amps, no? I spent the last few months working a 6v6 stereo amp, you work on music amps?

I have the same meter but it’s setup for -0- center so it shows negative current. Same plastic case. I glued a heavy piece of scrap metal inside to weight it down. I’m at the theatre now but I’ll attach a pic when I get home. It was dirt cheap for a zero center meter big enough to read across...

All bands (10-15 and 40-80) work well (5w in 500 out) but 20M remains a problem where output about 200w under same drive. Roller subject to arcing hoping para board helps.

Yes a turns counter would be useful. I have a page of notes to recall settings for each band. The top mesh cover allows me to see the roller and V caps for some setting info but it’s tedious to change bands. 10-15 and 40-80m input inductors set set. Still tuning 20m but I’m in the...

Thought I had too much stuff for an amateur / non-radio pro but the preceding pages made me feel a bit better. Next thread along this theme should focus on how big a collection of Parts & Supplies needed to keep the equipment going. How do you organize it all? I'm swimming in zip-lock baggies.

Why does a vacuum variable have bellows? If the concentric circles that mesh together and apart control the capacitance, and; There is a vacuum inside the glass tube itself, why is there any need for bellows? Bellows also look like copper. Having a quality capacitor helped me rank my...

Looks like it was packaged by Khrushchev himself. The foam inserts rotted and fall apart at the touch. A greasy mess but the cap is in a sealed plastic bag. Did they even have plastic back then? Package insert has several dates. A rubber stamp of 1991 and other handwritten and pre-printed...

The lowest Tune capacitance I can apply with an Air Variable is about 15pF. That minimum Tune C reduces PO by nearly 80%. Yet, with no Tune C connected at all (L network Tank) I see about 1:100 PO w/ reduced plate volts/mA. The RF Input parallel resonance revisions appear to work fine...

I assumed that the 750R RF swamping resistance was reduced by the .01uF bypass cap so it's closer to 450. I'm considering dividing one of the 1.5k resistors (the 2nd one after the trifilar on the way to band switch/tube grid) into 1.2k and 300. The 300 would be in series on the way to the grid...