Topband: Pro3 problem Correction.

[Herbert Schoenbohm]

Paul Beringer wrote:
> I want to thank all the informative e-mails received regarding the
> apparently well known problem of the RX antenna jack. I'll sort thru them
> and then come to a conclusion. You are a great bunch of guys.
> Mni 73
> Paul NG7Z
>
> _______________________________________________
>
>   

Paul, I'm sorry my reference was to the Icom 746-Pro radio not the 
756-Pro 3, a radio that I am not familiar with at all.  Most radios with 
an external RX antenna input have some sort of internal protection, a 
light bulb is not enough, or recommend a "front end saver" which is 
available from several vendors.  Yet I still recommend the simple 
circuit used for the 746-PRO, which has no separate RX antenna 
provision, in which a relay box with connectors is driven by the 8 volts 
available on the ACC socket.  This triggers some Darlington connected 
2N2222's and a small relay.  Extra contacts on this relay can also be 
used to trigger a relay at at the TX antenna which detunes it on RX thus 
reducing possible induced noise to the various RX antennas.

Again my challenge stands to be informed about any radio that has better 
160 meter low signal performance than the ICOM 746 PRO, with DSP and 
many DX and contest features, 6 meters, and you can still buy NIB for 
$1250 with a power supply. My only beef is that there is no separate RX 
antenna provision. 

I did not endorse the surgery to make a modification so the external box 
was easier and did not break the warranty.


73,

Herb Schoenbohm, KV4FZ