>
>
>> 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
>>
>>
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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