[hpsdr] Pentalop PA Consideration

[Mac]

I also have T/R relay or antenna changeover issue with Mercury. I'm using
just the Mercury /Ozy combo. I have a
transmitter running about 250 watts carrier - continuous AM. Using common
antenna so antenna removed from Mercury
and switched to transmitter via PPT on mike. That didn't work as Mercury
front end overloads. Next I tried to short Mercury ant coax going to T/R
relay (about 2 ft long shorted coax left on Mercury) as well as move ant
back to transmit via relay. That did'nt work as S meter pinned and all kinds
of scary stuff happens to console display.
Now I'm thinking that the input connection, pin 3 on K1 relay to pin 2 on
FL1 should be broken (interrupted) on transmit. Too bad there wasn't a
jumper there - heh heh. (see HPSDR mercury schematic: Front End).
But I guess I won't try that, and just accept the fact that if you use an
independant transmitter it must be low power and driven by penny under
software control.
Mac W6FCS



---- Original Message -----
From: "a.groff" <k0vm at mchsi.com>
To: <hpsdr at lists.hpsdr.org>
Sent: Wednesday, January 14, 2009 7:55 AM
Subject: [hpsdr] Pentalop PA Consideration


> ***** High Performance Software Defined Radio Discussion List *****
>
> I am in the process of patching Mercury and Pentalope into the 100 w PA
> of a 1970's transceiver.  In the process of setting up the driver levers
> in PowerSDR>Setup>PASetting , I observed that, on the higher bands, I
> started to to see the Mercury ADC OVERLOAD message...
>
> I can measure -15dbm on 80M up to +10dbm on 10M coming from the PA
> antenna change over relay back to the input of Mercury.
> This may be typical (??) isolation of a antenna change over relay and it
> may still be in the safe (??) range for the front end of Mercury, but PA
> designers (Thor ? ) and integrators should pay at least a bit of
> attention to this detail.
>
> AL, K0VM
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