[Milsurplus] Strange AN/URC-9 followed me home from Dayton

[Nick England]

Well, maybe I should have said AN/GRC-138. Looks like a USAF contract
number to me. See photos at the bottom of this page.
http://www.navy-radio.com/xmtrs/src20.htm

Unlike the Navy URC-9's that I wrestled with 40 years ago, this has no
blower inside the RT compartment. Instead there is a duct leading from the
p/s fan into the PA compartment. Exhaust is via a cutout side slot from the
RT compartment.

In the original Navy URC-9, the p/s fan blew air around the RT enclosure
heat exchanger, but there was no air path to-from the RT unit. A blower in
the RT unit recirculated air inside the RT compartment. Around 1972, our
group at NAVELEX finally got a field change approved to cut holes from the
RT unit into the heat exchanger air flow. Tubes were much happier then.
cheers,
Nick England K4NYW
www.navy-radio.com