[Milsurplus] NDB's and tank radios

[Charlie L.]

The rate of NDB shutdowns may be slowing or stopping.  It is still the
least expensive navigation aid out there, and pilots still like a needle
that swings around and says to fly 'thataway', as opposed to discerning
what his screens tell him.. Small municipal and county airfields can afford
an NDB with minimal expense and maintenance, compared to an ILS.  The FAA
is also backing off on turning off VOR and TACAN equipment, a mountain top
VOR near me slated for shutdown has been resurrected and money spent on
improvements.  Apparently the military is also  finding out TACAN can not
be fooled like GPS.  The only difference in a standard VOR/TACAN station,
VORTAC, and a VOR/DME only (Distance Measuring Equipment) is the rotating
antenna is turned off and power reduced to 1KW out.  When the solid state
second generation VORTAC came online in the mid 80's, the TACAN ran at 5KW
out, the same as the old tube set that used a SAL89 Klystron with 12KV on
the cathode, but the fancy solid state system started blowing amplifiers,
of which three were 10 at 500 watts each, fed by a 1 to 10 splitter at 100
watts in, and then into  a 10:1 combiner for 5KW out, but they started to
burn up and it was too expensive to fix, so reduce power to 1KW.  GPS still
cannot be used for a precision approach landing due to ground reflections,
which are multiplied on an approach over water, so  V/UHF ILS gear is still
the norm, the latest model being installed right now the ILS 420.  It has
only two adjustments, the rest are software.  A few years ago, an ILS could
have 100 pots to turn to align it and its monitors.

Probably the biggest failure in the tank radios depicted in Fury, was in
the crystals.  The crystal used in those radios was notorious for going
bad, many not even making it across the pond to the ETO, just going bad in
transit.  I had a complete unused set for that radio in the felt lined box,
and checked all 100 of them, only two worked.  I swapped them all to the
new AF4K crystal guy for a good 160 meter crystal.

Charlie in NC
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