ARC-105 Letter From Naval Veteran
Back
to Phoenix W7CPA Page
w7cpa@arrl.net
Dear Sir,
I thought I'd
lend some info regarding the ARC-105 HF you're working
on.
I'm a retired
Navy avionics tech (AT1) and worked on the EA-6B Prowler my entire career. Most
of my hands-on time was spent working on the Improved Capability II (ICAP II -
Block 82) version of the aircraft which had the ARC-105. My level of
maintenance was performing on-aircraft work so I never had an opportunity to
actually open the various avionics boxes. If we troubleshot down to a
particular unit, it would be removed from the aircraft and sent to the next
higher level of maintenance where those techs would remove the covers and
troubleshoot to the component level. Meanwhile we would receive a replacement
unit to get the aircraft flying again.
One of the
inspections performed every seven days involving the ARC-105 was to pressurize
the RT with 10 PSI of dry air. The avionics shop had what resembled a
ruggedized bicycle tire pump filled with desiccant. You didn't want to add
moisture to the RT. The HF antenna coupler was pressurized to 7 PSI. We used a
standard tire pressure gauge to check the PSI. It was a low-tech process but
worked fine.
When dialing
in a freq on the cockpit box, I recall a rather loud tone in the headset when
the tuner in the RT was changing freqs. It was best to remove the headset or
turn down the volume.
The skin of
the aircraft was one half of the antenna with the other half of antenna being
contained in a non-metallic "rib" structure on the top of the aircraft, aft,
just forward of the tail. If we were on the ship and needed to test the HF we
would have to get permission to remove as many tie-down chains as possible
otherwise you basically were grounding the antenna. You would also make sure no
one was touching or leaning on the aircraft skin otherwise they would get a 400W
nasty surprise. I saw that happen once. :-)
Besides the
tactical use of the radio while we were overseas, when airborne the flight crew
would use the HF for contacting HAM stations back in the states to make phone
patches to call their spouses using MARS.
http://en.wikipedia.org/wiki/Military_Affiliate_Radio_System
I hope I
helped in some way.