Recent content by nomadradio

That is massively cool! Too late in the day to dive into it, but this appears to be what I've been looking for. Or at least a proper starting point. Thanks for the link. 73

Scored a power transformer for a Palomar 300A. Didn't cost me an arm and a leg. I was impressed by how it was packed. Yes, the fiberglass strapping tape had to be cut to open the outer carton. The inner carton was reinforced the same way. And there was no empty rattle space. The...

The only radio I remember seeing with a ANL (Automatic Noise Limiter) active for SSB receive was the Siltronix 1011 series of radios. ANL simply "clips" noise peaks to bring them down to the same amplitude as the voice modulation. Also tends to distort voice peaks, especially from an...

Is this problem confined to 10 meters only? Or does this occur on other bands? Or for that matter, only when using the 10-meter antenna? What the radio does into a dummy load could be quite instructive. 73

Grid-driven tetrodes require a parasitic-suppresion choke between the control grid and everything else. Don't see any in KK5DR's examples. Never heard of this guy, but if he simply added that to the "passive grid", or "swamped grid" amplifier, he wouldn't need to be so concerned with VHF energy...

Not something I ever tried. Won't be useful without a way to bypass it while transmitting. 73

Biggest thing I didn't like was the channel 9/19 scan feature. Used a big, fat PROM chip between the channel selector and the PLL. Learned to hot-wire the radio for normal channels only so the channel 9/19 dual watch wouldn't go psycho when it felt like it. Never did get to the bottom of why...

The way this was explained to me has to do with the high cost of aluminum in Japan. If you can use less of it in your capacitors, your manufacturing cost drops, gives you an advantage over competitors. Milling aluminum foil ever and ever thinner is what caused aluminum electrolytics to shrink...

Ancient principle called Occam's Razor. Says that all things being equal, the simplest explanation is the most likely. 73

Somebody (else) needs to trace down the schematic for this circuit board, and produce a placement diagram. This was how Howard Sams did it in the 60s and 70s. Called their method "Circuitrace"(tm). 73

Yep. The blanker is fed directly from the antenna in this radio, and the assumption is that noise at 23.5 is the same as what's entering the main 27 MHz signal path. 73

Plate dissipation for that tube is 17 Watts. For an amplifier with roughly 50 percent efficiency, you'll throw one Watt of heat to the two tubes' plates for every average Watt of RF output. Round it up to 35 Watts average output from the thing, and with 100% modulation that would be 140 Watt...

Yep. What radio do you want to add this to? The tapoff point for the blanker's input, and the 'clamp' spot where the main signal gets blanked have to be timed correctly. The noise pulse gets delayed differently inside the blanker circuit than it does passing through the main receiver's...

I hand wired a prototype PLL channel selector with the digits wired in reverse order. Made the digits upside-down. At least they lit up. 73

Highly modded homebrew adaptation. Don't recognize the original model or type before it was modded. Don't see a power supply. The empty space at the rear has a 8-pin Jones plug that probably connected to a dynamotor. It would have served to provide B+ and filament voltages. The push-pull final...