Operating conditions of the 809 are 370V on the plate 60mA which gives me close to 20 watts carrier output. Using Grid Leak, the drive hungry 809 Triode is operating at 8x cutoff just under it's max grid specs, which gives me an ultra narrow conduction angle with extreme modulation linearity. The 6146 drives the piss out of the Medium Mu 809 Triode RF Final into Deep Class C.
The RF Section was redesigned to use the 6AQ5 as the Buffer/Multiplier driving the 6146 as an RF Driver using hand wound, plug in coils for it's output tank.
Improvements were definitely mandated.įirst things to go were the 6AG5 Buffer/Multiplier, 6AQ5 RF Driver, & the 6146 RF Final. The 6146 RF Final had horrible Modulation Linearity no matter what you did with the drive and the screen. Not to mention that it looked like a complete horror show on the Scope.
The Modulator was full of distortion, limited in frequency response, and lacked enough balls to fully modulate the rig. With the Power Supply built, the stock AF-67 was hooked up and tested. The classic brute force design was followed using a pair of Murky Vapor Rectifiers followed by a choke input filter and voltage divider/bleeder resisters. This was accomplished but there were no "small" parts available, so everything is HUGE and was built breadboard style being a temporary shack and all. Easy enough solution, just go out into the barn and get the parts to cobble one together. I remembered there was a Multi-Elmac AF-67 Exciter shoved up on a shelf somewhere that would match up nicely to one of the R274/FRR Receivers, but it had no power supply. Now that a location for the temporary shack was secured, a decision had to be made on what to put in it. Being in a hurry to get something on the air, this room was not remodeled and remained in it's feminine state as the shelves and benches were stacked and assembled. It was a "girls" room and had been painted pink with little frilly thingies on the light switches and such.
I thought I would add to that with some schematics and some history.Īs the slow process of getting the new shack built proceeds (it seems like it will never get accomplished), there had to be somewhere to play radio in the meantime, so one of the spare bedrooms in the main house had been designated as the temporary shack. I've made mention of my temporary AM Station on this forum a few times, sometimes posting pictures of the old buzzardly layout. Here I sit once again sleepless, listening to white noise and static crashes on the Hallicrafters R274/FRR as my mind wonders endlessly around in infinite little circles.