[Milsurplus] NDB's and tank radios

[Brenda Gentry]

Shutting off LORAN was a ghastly mistake. Sailors, especially on the 
Great Lakes, were furious. Afterwards, many stations were scrapped, then 
there were orders to not wreck any more  stations. There is a backward 
compatible version called LORAN E supposedly undergoing tests. LORAN  
works fine in urban canyons and other places GPS can't reach. I believe 
it will work indoors in some circumstances. I worked on TACAN 
transmitters, the GRN-9 during my time in the Air Force, as well as the 
MRN-7 and 8 ILS system. Tuning the SAL-89 klystron required patience and 
reaching behind with 12 KV nearby to make the tuning adjustments was a 
bit unnerving, even though it was well isolated and shielded from 
contact. I won't forget climbing the tower in the middle of the night to 
change the tachometer generator on the antenna either.  I made the last 
voice transmission on the NDB at the outer marker of Griffiss AFB before 
turning it off.  I was officially trained in ground radio but short 
staffing allowed me to transition to navaids. After a couple months, my 
craft code was changed to match my work. Maybe not  kosher, but in 1972 
if they needed to overlook details, they did.

     B. Gentry, KA2IVY

On 12/4/25 6:10 PM, B. Smith via Milsurplus wrote:
> Our Shut Down blunder was Loran C.
> K4CHE
>
> On 12/4/2025 5:40 PM, Charlie L. wrote:
>> 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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