[Boatanchors] Receiver Antenna Input Question

[rbethman]

There is a BIG difference in aviation installations vs. ground 
installations.

The helicopters that tie to power lines at 250KV while the lineman works 
on a problem is a clear indication that an aircraft with NO ground 
connection does things that a ground mounted radio with an antenna in 
the air will NOT do.

Avionics installations are apples and oranges when tossed into the fray 
with ground communications.  Aircraft ALSO sustain direct lightning hits.

The solid state Harris radios in ground use, had TWO distinct problems.  
1)  heat - the filters constantly clogged with the talcum powder 
consistency "sand" of the desert.  2) The static developed across the 
antenna discharged into the front ends and fried them.

Bob - N0DGN

Francesco Ledda wrote:
> It would be interesting to see some actual government documentation showing
> R390s being shipped to the Iraq war.  Personally, I don't believe it!
>
> We have been using SS front ends on avionics boxes for 40 years, and they
> have been able to deal with lots of static charges with no issue.
>
> Regards,
>
> Francesco Ledda
>
> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net
> [mailto:boatanchors-bounces at mailman.qth.net]On Behalf Of rbethman
> Sent: Monday, March 02, 2009 11:02 AM
> To: Carl
> Cc: boatanchors at mailman.qth.net; J Forster
> Subject: Re: [Boatanchors] Receiver Antenna Input Question
>
>
> Yes, they don't do diddle for SS radios.
>
> That is precisely why pallet loads of R-390As got shipped into the
> Middle East during Desert Storm.  The "new-fangled" solid state
> receivers had their front ends fried, and their filters clogged.  They,
> the R-390As, indeed DO have a large neon bulb in the antenna relay
> housing to discharge the static buildup from the antenna system.
>
> Bob - N0DGN
>
> Carl wrote:
>   
>> They found that out decades before Desert Storm. However a neon has a
>> rather long delay before it fires if it isnt biased to a more useful
>> voltage. SS front ends would be fried otherwise and I dont thing they
>> were using tubes in 1991. For SS there are better choices.
>>
>> Carl
>>
>>
>> ----- Original Message -----
>> From: "J Forster" <jfor at quik.com>
>> To: "Carl" <km1h at jeremy.mv.com>
>> Cc: <boatanchors at mailman.qth.net>
>> Sent: Sunday, March 01, 2009 8:49 PM
>> Subject: Re: [Boatanchors] Receiver Antenna Input Question
>>
>>     
>>> Wind and dust can build up significant static. They found that out in
>>> Desert
>>> Storm. Likely on planes too, from tiny water droplets.
>>>
>>> Hence the NE-2s.
>>>
>>> -John
>>>
>>>
>>> Carl wrote:
>>>
>>>
>>>       
>>>> By the time a NE2 fired at 90V the front end coils would be fried
>>>> especially on the lower bands. The Navy used a neon bulb to protect
>>>> front ends from TX antennas that were often only 50' away but it was
>>>> biased so it fired at a much lower voltage. It was also much more
>>>> robust
>>>> than a NE2.
>>>>
>>>> A neon will also bleed off lightning charge buildup from a nearby
>>>> strike
>>>> or cloud to cloud discharges. With a Beverage antenna its not even
>>>> local, Ive been bit by a strike several miles away.
>>>>
>>>> ARC-5 receivers had a NE2 or similar which was effective against the
>>>> fairly low power of the matching TX.
>>>>
>>>> Carl
>>>> KM1H
>>>>
>>>>         
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>>     
>
> --
> Bob - NØDGN
>
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-- 
Bob - NØDGN