[Milsurplus] NDB's and tank radios (Brenda Gentry)

[Charlie L.]

I had a dual main and standby GRN9C set up at an FAA VORTAC site.  It also
had dual monitors with over 100 tubes in each.  It was fairly reliable
equipment towards the end of its life, but the main issue was the paper
mill down the road.  The air was the issue, and it caused the phenolic
circuit board to arc over between terminals that had as little as 250 volts
on them.  It was a constant battle to scrape the boards clean of the carbon
trace, and seal them back up with Conformal Coating.  When they were first
installed in the VOR building, there was no air conditioning, just a large
vent fan, and this was in FLA.  The VOR was old, installed in 1938, and
consisted of an 807 oscillator tube, feeding a 4-125 multiplier, a 4-125,
driver, a pair of 4-125's on the PA, modulated by a pair of 4-125's.  Made
tube stock easy.  It was a very reliable piece of gear that was  removed in
1984 and sort of interesting that the 46 old VOR removed in 1984 and
replaced by the  LSI and uProc based 2nd Gen VORTAC, the 2nd Gen gear is
now 41 years old.

In the 'only vent fan days'It was common to be working in shorts, flip
flops and no shirt in the middle of the night to get the GRN 9 back on the
air,  just sweating like a hog.  They finally installed AC, and reliability
went through the roof.  But Jimmy Carter and his N-R-G program to save
electricity, that actually instructed us to turn the AC off unless the
building was manned, and the TACANS started dropping like flies.  We
ignored his presidential directive and left the AC's on.

The AF approached the FAA into providing funds to help develop the solid
state TACAN antenna, but they refused.  The AF completed the project and
the FAA said, neat, we want some.  True to the 'LIttle Red Hen', the AF
told the FAA to pound sand, and  the FAA continued on with ex-shipboard
antennas minus the gyro stabilization.  Today, the AF does not need their
solid state baby and the FAA has access to the modern design antenna if
they want.

In regard to LORAN C, it was better than GPS anyday.  The AF installed
monitors at many VOR and VORTAC sites as there was a telco line available,
even in the middle of nowhere, to monitor the LORAN  C signal nationwide.
The FAA had planned to install mid country LORAN transmitter  sites to give
full US coverage, but they were talked out of it by the GPS crowd and there
be all, end all promise of GPS.  At the time, many private aircraft had
LORAN C installed and were using it to navigate without the use of the VOR
with much better accuracy, and controllers had LORAN C parameters they
could give a pilot using it.  If there is any plus to the loss of the
2MHZ,  LORAN,  it is the loss of the QRM and also, states like FLA can run
1kW now, when they were restricted to 25 watts at night on 160 meters.

Another big setback was the MLS, Microwave Landing System.  The US system
won out over the British system with ICAO approval, but it ran afoul over
one simple thing.  The whole world is set up for an approach to an airport
that is inline with the runway, with a 3 degree glide path out 5 miles or
more.  The MLS allowed multiple approaches at the same time from just about
any angle, hi, low, left right, anywhere in front of the antenna.  PATCO,
the controller union, raised a lot of objections to this, pointing out the
workload increase where now you could have  something like a helicopter
coming in at a very high or low angle from a way off normal approach course
direction, but this would still require only one aircraft to be basically
'landing', cleared to land at the same time, even though the system could
accommodate many on approach aircraft simultaneously.  The last test bed
MLS was in SC, removed and sold govt. surplus quite a few years ago.

Charlie, W4MEC in NC
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