Ver6.1 Rocky image rejection ... power saturation
- View SourceHello guys ... I've been too busy using the Ver6.1RxTx and other
things to follow up on a discovery...
I seem to have an "issue" with my Ver6.1RxTx that I was unaware of
When doing alpha testing of the Rocky3.0 I was having problems with
setting the image rejection. Alex indicated that I was the only one
that he was aware of that was having that problem. I discovered then
that if I reduced the I/Q drive in the TX setup in Rocky I could set
the rejection without problems. I worked a few stations with Rocky,
but continued to use M0KGK's software. I never really thought much
more about it.
Last weekend, Alex released Rocky 3.1 with PSK ... Oh my!! I thought
it would be lots of fun to run PSK31 with Rocky since it was a mode
option and no additional software was required. So I loaded 3.1 and
went to work ... once again I could NOT get the image rejection to do
much at all. (Hummm just like when I was testing 3.0). I have no RF
power indicator on the Ver6.1 so I pulled out the scope and hung it on
the RF output of the Ver6.1 and discovered the reason ... something in
the TX side of the 6.1 is saturating ... I had 10db more I/Q input
than what the the 6.1 would take. I reduced the I/Q level with the
level control on the TX setup in Rocky3.1 by 10db, just below
saturation and image rejection could again be set very well ... image
into the noise, no problem.
I have not tried to trouble shoot yet ... I need to get the scope
out again and try to find what is saturating.
I'm guessing that this is the reason my Ver6.1 will not run more
than 500mw output (both on 80 and 40m)...
So if you experience problems setting Rocky image rejection, be sure
you are not saturating ... Why this is not a problem when setting
image rejection with M0KGK's software, I don't know ... I would guess
I can reduce the image with it even more if I reduce the I/Q input level.
I'm having a "blast" running PSK31 with Rocky and the Ver6.1 now ...
that's taking time away from my QRPp CW QSOs..
73 and good Softrock DX to all, watch for me on 40m ... Bill K0AWU