[Heathkit] SB-300 Question

[Edward B Richards]

Sounds to me like your antenna is not tuned to your operating frequency.
With the shield open, the whole thing; antenna, coax, etc acts as a long
wire, not tuned to any particular frequency. When you connect the shield,
then only the antenna is used. I think you have antenna trouble. Good
luck.

73, Ed Richards, K6UUZ
Simi Valley, California, 93065
Home of Air Force 1 Pavilion

On Sat, 12 Nov 2005 23:35:08 EST KHeck73 at aol.com writes:
>  
> In a message dated 11/12/2005 7:38:11 P.M. Eastern Standard Time,  
> w3wjr at aol.com writes:
> 
> I just  received an SB-300 with a small problem. Before I dig into 
> it, I 
> figured I  would ask for hints.
> 
> Unit works pretty well as long as you leave the  outer jacket of the 
> coax 
> disconnected. When its connected the receiver goes  deaf.
> 
> 
> 
> ..
> Great question, because I have an SB301 that does the same thing. 
> The coax  
> is not shorted, and it happens even without the coax shield being 
> grounded  to 
> earth. The unit receives fairly well with only the center conductor  
> 
> connected. I also note that the chassis has a slight voltage on it. 
> I get  weak sparks 
> when connecting or disconnecting the ground wire. I connected a  
> voltmeter 
> between the chassis and earth ground, and a voltage slowly swings  
> about plus 
> then minus 80 millivolts in a six second cycle. This might be 
> normal,  I don't 
> know. But, I think the problems could be related because the  
> receiver blanks 
> out stronger from the coax shield effect when the chassis  is 
> grounded. 
> Something is slowly charging and discharging,  but that's as far as 
> I got.
>  
> -Karl.
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