Don't bother with screen modulation. There is modulation iron available, although it might be 50% bigger than you need because it is for higher current.
Two 225-400 MHz military radio sets have nice 120-150W modulation transformers that go from 200Hz to 20KHz. The mod iron has a high DC rating in the secondary because of the lower efficiency of the finals at 400MHz.
The modulation transformer from an
MD-141 is rated 120W and 200-20000 cycles. I think the one from the
MD-129 is 150W and the same HF response. They are designed or 850V B+
The AN/GRT-3 consists of the T-282 transmitter and MD-141 Modulator, and accessories. Accompanying receiver: the AN/GRR-7 consists of the R-361 Receiver, and accessories.
MD-141:
T201
Z: pri: about 8k to 2.8K, voltage ratio about 1:1.18
Eb 850V
mod: two 811A
RF two 4X150, 100W carrier, 290mA meter reading
aux winding: C.T.'d winding for voltage feedback or AMC
screen modulation circuit:
http://amfone.net/Amforum/index.php?topic=35905.msg276191#msg276191The AN/GRC-27, AN/GRC-27A, or AN/GRC-48 consist of the T-217 transmitter, MD-129 Modulator, and R-278B Receiver, and accessories. The modulator has collins iron, not that it matters whenit is military.
MD-129:
T1404
Z: 5500CT to 2400 Ohms, voltage ratio 1:1.32
Eb 850V
mod: two 4-65
RF two 4X150, 100W carrier, 350mA DC
aux winding: C.T.'d winding for voltage feedback or AMC
aux winding 2: 600 Ohm output 50W MAX. for remote operation sidetone
screen modulation: dropping resistor in TX from mod. B+
manuals are here:
http://www.bunkerofdoom.com/lit/mil_uhf_01/index.htmlI have spare modulation transformers from some parted out MD-141s. If you want one PM me.
I have one of the little T-282 screen modulators as well, if wanted as well as three T-282s in fair cond.
The only pic I have of any of them is of the 150W one in the MD-129, just so you know what to look for.
I have only complete MD-129 modulator/power supply units, no parting out.