[Boatanchors] Receiver Antenna Input Question

[WA5CAB at cs.com]

In the later model BC-224 and BC-348, a 1 MEG resistor was added across the 
antenna terminals to accomplish the same thing.

In a message dated 3/2/2009 10:54:09 AM Central Standard Time, al at ar88.net 
writes: 
> OK, back to the original question.
> 
> There are at least two different antenna input configurations being 
> discussed here.  (I couldn't find a 75A-2 schematic.)
> 
> 1. - Receivers designed for short (high-impedance) antennas, e.g. the 
> "ARC-5's" and the Collins R-388, 51J-3/4, etc.:  The antenna terminal 
> connects to the "top" of the first-RF-amplifier tuned circuit via a 
> small capacitor.  There is no DC path from the antenna terminal to 
> ground.  I this case, a gas tube or neon bulb is in order to bleed of 
> static build-up from the antenna, and perhaps provide some measure of 
> protection from overload.  I suspect there is also a real-world chance 
> of a couple of KV of static damaging the coupling cap.
> 
> 2. - Receivers designed for low impedance antennas, e.g. your NC-303:  
> The antenna terminal connects to a primary winding on the input tuned 
> circuit.  The other side of the winding is grounded.  In this 
> configuration a neon bulb is nearly useless as it could fire under only 
> the most catastrophic circumstances.  Any static will bee drained off 
> through the primary winding.
> 

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480