[Boatanchors] How much is too much?

[howard holden]

The R-388 uses a neon across the antenna input.

How about using a pair of diodes back to back across the input? 

Howie WB2AWQ
  ----- Original Message ----- 
  From: w8au at sssnet.com<mailto:w8au at sssnet.com> 
  To: boatanchors at mailman.qth.net<mailto:boatanchors at mailman.qth.net> 
  Sent: Saturday, January 29, 2011 7:53 PM
  Subject: Re: [Boatanchors] How much is too much?


  At 07:33 PM 1/29/2011, Jim Haynes wrote:
  >I recall some old military tube equipment that had something like a neon
  >bulb across the antenna terminal to ground.  Doesn't seem like that would
  >limit the voltage enough, but maybe it did.

  The old military receiver input Z's were typically 300 ohms or more, plus
  the separate receiving antennas could approximate hi-Z also.  This
  made NE-2 neons somewhat protective at an ionization voltage of 85-90 V.

  Today, at 50 ohms Z, neons would not be 
  effective.  (Watts=E2/R)  90(squared)/50= 162W (!)

  Consider checking out the Navy R-1051G receiver input protection circuit, if
  you are serious about mutual coupling of close antennas.  It provided an
  instantaneous hi-level attenuator switching arrangement.

  Perry  w8au



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