[AMPS] 3CX800

[Peter Chadwick]

> Rich says;
> 
> >?  Unless one can tolerate the attn loss during Rx, one still needs a 
> >high speed relay at the attn.  
> 
> No way! You have a c/o relay at the antenna. Antenna connects to common.
> Amp goes to one contact (my preference is for n/c); Rx auxiliary antenna
> input goes to n/o contact: the switch is moved on the xcvr to use the aux
> ant input. No extra switching needed - just interlock or whatever to
> ensure that the relay on the ant doesn't hot switch.
> 
> Reason for 'energise to receive' is that when you've switched off, the
> antenna is connected to the plate of a big tube. That tube is more likely
> to withstand high static discharges than a relatively small semiconductor
> device.
> 
> I did design a receiver protection unit some 30 odd years ago for a marine
> receiver: we protected against a discharge of 1.5 microfarads charged to
> 15kV straight into an rx front end which used tuned circuits stepping up
> to a JFET. Even so, I'd rather disconnect the antenna with the realy
> switching.
> 
> 73
> 
> Peter G3RZP
> 
> 

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