On Mar 30, 2025, at 18:07, Francesco Ledda via Milsurplus <[email protected]> wrote:I believe to be a linear. If you are interested, I have its schematic.______________________________________________________________Best, Francesco K5URGSent from my iPadOn Mar 30, 2025, at 19:24, Brenda Gentry via Milsurplus <[email protected]> wrote:I had plenty experience with GRA-53 transceivers. They are very proficient in cremating themselves. Unauthorized fans on the outside of the cabinet helped a little. The worst were ARC-27s used in GCA trailers. They cooked themselves so badly everything inside was dark brown. Is the SRC-20 amplifier a linear or does it have a modulator driven by the exciter? Near the end of my term in the Air Force, we got some VHF transmitters that used a 10 watt AM exciter to drive a one tube linear to make 40 watts. Linear amps and AM are so inefficient. GRC-27s were huge and heavy, but were plate modulated and put out a good signal.
B. Gentry, KA2IVY
On 3/30/25 7:00 PM, Jim Whartenby via Milsurplus wrote:
______________________________________________________________I would say that the URC-9 is similar to the VRC-24 in that both are UHF Transceivers and that the modules look to be similar but the modules are not interchangeable, specifically the PA module. Now the TRC-68, GRA-53, GRA-54 and the VRC-24 all seem to have the same modules, but I never worked an the VRC-24 which is a 28 volt DC powered unit.
When I was in the Air Force, stationed in the Philippines, I worked on the TRCs and GRAs. They ran so hot that one had to wait half an hour for the R/T unit to cool off before you could carry it back to the shop. Fun times!
The URC-9 was Navy equipment and they never seem to buy "off the shelf", they always have to change things! <grin> The URC-32 vs the KWT-6 Type 8 is another example.JimLogic: Method used to arrive at the wrong conclusion, with confidence. Murphy
On Sunday, March 30, 2025 at 04:56:21 PM CDT, [email protected] <[email protected]> wrote:
More info below:
https://www.navy-radio.com/xmtrs/src20.htm
From: [email protected] <[email protected]> On Behalf Of [email protected]
Sent: Sunday, March 30, 2025 4:54 PM
To: 'Gary Hitchner' <[email protected]>; [email protected]
Subject: Re: [Milsurplus] 400 MHz cavityGary,
The cavity amp you have was part of the Collins AN/SRC-20. The transceiver/exciter is the AN/URC-9, also known as AN/VRC-24.
It is a nice amp that can be easily tuned to 432 MHz.
Best, Francesco K5URG
From: [email protected] <[email protected]> On Behalf Of Gary Hitchner via Milsurplus
Sent: Sunday, March 30, 2025 2:50 PM
To: [email protected]
Subject: [Milsurplus] 400 MHz cavityList,
I have two of these which are going to scrap unless someone tells me there is a reason not to. (Or picks them up local). Large and heavy.
These are a 225- 400 MHz cavity that used 2- 4CX250k’s in parallel, evidently conversion to 432 was possible, but a project. Fair Radio might have had them in stock for a while, or maybe Skycraft, not sure.
Often wanted to see the entire assembly these were in, must be something to see………….
Gary
WA2OMY
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