[Skimmertalk] Red Pitaya 1:14 impedance transformator + SV1AFN pre-amplifier

Lee Sawkins ve7cc at shaw.ca
Mon Oct 23 04:02:12 EDT 2017

I have found an easy way to accurately measure exact s/n ratio changes in any skimmer system.  This only requirement is a having a beacon or other reliable signal within ground wave range.  I have a beacon on 10 meters that I use.  Simply see what the skimmer is giving for a s/n report for this signal.  Then make your changes such as adding a 14:1 transformer, a pre-amp, or an inline filter etc.  After each change, wait a while and see what the new s/n report is.  The difference between the new and old reports is the exact difference caused by whatever you did.  This method is accurate, repeatable, and requires no test equipment.

Lee VE7CC  

----- Original Message -----
From: DD5XX (Saki) <dd5xx at web.de>
To: skimmertalk at contesting.com
Sent: Mon, 23 Oct 2017 01:15:09 -0600 (MDT)
Subject: Re: [Skimmertalk] Red Pitaya 1:14 impedance transformator + SV1AFN pre-amplifier

Hi Martin,

thanks for feedback. I think I will order one from SV1AFN. I already did
send him an email with some questions yesterday. Hopefully will order
one this week. Thanks again and have a nice week.

Best 73
Saki, DD5XX

Am 23.10.2017 um 01:32 schrieb Martin Rath:
> Hi Saki,
> I use Maki's J310 LNA in front of the red pitaya for 2 2 reasons:
> 1) additional gain. As per Maki himself the res pitaya requires an
> additional 5-10 dB amplification.
> 2) to protect the inputs: less than 2 were after i got the RP a close
> by lightning took out the AD8066 op amp. I did manage to replace don't
> want to so that all too often: Singapore gets hit by major t-storms
> over 200 days per year. Running a skimmer here is not always easy as i
> cannot always be home to unplug the antennas. I would much rather have
> to replace a J310 than the AD8066 another time.
> I'm happy with the performance. I'm still waiting for one 14:1
> transformer but it's already on the way.
> 73's Martin 9V1RM 
> On Mon, 23 Oct 2017 at 00:13, DD5XX (Saki) <dd5xx at web.de
> <mailto:dd5xx at web.de>> wrote:
> Hello all,
> thanks to Bob (N6TV) I got one of those Red Pitaya impedance
> transformator 1:14. I wonder if anyone did try to add a
> pre-amplifier on
> the input and if so what is your experience ? I have heard and did
> read
> lots of positive feedback on the pre-amplifier offered by SV1AFN
> on his
> website. I would be interested in the kit "J310 push-pull HF pre-amp
> 0.5-54MHz" (see "https://www.sv1afn.com/j310preamp.html"). Do you
> think
> to gain some more dB performance with this combination ?
> Red Pitaya INPUT1 <---- 1:14 impedance transformator <---- SV1AFN
> pre-amp
> Looking forward into your comments.
> 73
> Saki, DD5XX
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Vy 73s de DD5XX

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