[TangerineSDR] 10 Mhz leakage

Gerry Creager - NOAA Affiliate gerry.creager at noaa.gov
Tue Jun 2 13:31:08 EDT 2020


Have you sent a report to Flex? I know a couple of the folks, and suspect
that, if it's real, they'd want to know about it.

gerry n5jxs

On Tue, Jun 2, 2020 at 3:05 PM Engelke, Bill via TangerineSDR <
tangerinesdr at lists.tapr.org> wrote:

> A little discovery that might have a bearing on something in the
> TangerineSDR…. Or maybe this is just my ignorance at work.
> We’re putting a lot of emphasis on being able to observe the doppler shift
> of WWV, often focusing on 10MHz. I have been looking at this using
> FlexRadio 6600 and Spectrum Lab. In observing the frequency moving around
> quite a bit (by this I mean 20 to 40 millihertz), I thought, maybe that is
> the Flex’s TXCO doing its thing. So I got a Leo Bodnar GPSDO and started
> using this as the Flex’s clock.
> What I noticed is that even with the antenna grounded and the rig
> connected to a dummy load, there is a pretty significant (and totally
> stable) 10 MHz signal shown in Spectrum Lab. I speculate that this is the
> clock signal finding its way into the front end of the receiver. So, when
> watching for WWV doppler shift, I see a 10 MHz signal (which is comparable
> in strength to WWV) superimposed on it.  The same signal can be seen on 15
> MHz and 20 MHz – not surprising, since the Leo Bodnar GPSDO provides a
> square wave output (i.e., rich in harmonics). I recognize that the Flex is
> not a lab instrument, so I have no grounds on which to complain, but still…
> I wonder if this will play into the Tangerine SDR?  Are we able to keep RF
> from the clock from leaking into the front end and overlaying the WWV we’re
> trying to observe? Do we need to?
> Any thoughts?     -73- Bill AB4EJ
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Gerry Creager
*The way to get started is to quit talking and begin doing.*

*   Walt Disney*
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