I’ll keep this one short and sweet. I mostly want to keep some pictures here. This is a site owned and operated by Scott Scarborough (Showcasesound.com). Located atop a grain silo, this is a roughly 1.5-2kW 4-bay FM transmitter.
Here’s a view of the grain silo that the antenna is on.
The astounding views from atop
Okay, now for the actual transmitter equipment. Ray actually invited me out to what was supposed to be a quick jaunt, but turned into an all-day affair. This is mainly because everything was wrong with this Armstrong class C, tube transmitter. It’s rated for 3.5kW, but we only ever got it to something between 1.5 and 2kW. Most insane is the tuned cavity linearizing filter. The rocker buttons on the front adjust the two plates, one by the tube, and the plate that slides up and down. These adjust output capacitance and inductance. You can even see someone’s tuning marks on the side of the cavity. We ended up back inside this thing because we couldn’t get the transmitter to stay on. This turned out to be a tuning issue. Since there is no indication on the front of where the components are set, we couldn’t get it right before it cut out with a VSWR warning. After getting back there and setting it correctly by shouting position and movement to Ray, we were able to get the TX running. This is fed with an exciter and IPA. The Exciter produces about ~7W into the IPA which produces a ~200W drive to the HPA.
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