[Lf] RE: [RX320] question on calibration? (fwd)

[Frank Gentges]

LFers,

If you are not on the RX320 listserver you might find this interesting.
We are getting some fine accuracies on these RX320s now.

Frank K0BRA

---------- Forwarded message ----------
Date: Sat, 8 Jan 2000 04:09:59 +0000 (GMT)
From: Frank Gentges <gentges at itd.nrl.navy.mil>
To: RX320 at onelist.com
Subject: RE: [RX320] question on calibration?

Shaun,

It is good to hear of your successful results and extension to Clifton's 
program.  I would like to take your notes and add them to the AMRAD web 
page because they might be helpful to many.

I was bothered about the fact that higher frequencies were lower on the
spectrogram and vice versa.  If you enter -1000 Hz into the BFO frequency
setting on Gerd's program it accepts it and really does reverse the
spectrogram.  Negative numbers in Clifton's program work similarly. 
Clifton's PassBand shift works too.  Now to get Spectran to show 1000 Hz
as zero Hz and the numbers on each side with pluses and minuses. 

Thanks for you input. Somebody is using this stuff!  AMRAD is going down 
to Nags Head NC this month for an LF DXpedition with our RX320s, 
notebooks and Spectrans etc. and see what we can catch.

Frank K0BRA

On Fri, 7 Jan 2000, Shaun P. Merrigan wrote:

> 
> 
> > Jim and all,
> >
> > If you take the output of the RX320 and plug it into your sound card you
> > can observe a spectrogram on your computer and easily resolve 1 Hz.  We
> > set up our system to output 1kHz when the RX320 is on CW and tuned to the
> > carrier frequency.  We can get the tracking to go from 60 kHz to 15 mHz
> > to within a couple of Hz or better.  Room temperature changes will
> > degrade that tracking to 10 hz or so after a few days.  Much more detail
> > at <www.amrad.org/projects/lf> and look around at what AMRAD is doing for
> > our RX320 calibration info.  Also on that page is a link to the
> > modification to extend the RX320 down to 10 kHz.
> >
> 
> 
> Hi Frank,
> 
> Regarding the RX-320 and frequency measurement, I have read and tested the
> procedure on the AMRAD site, and I would like to offer a few comments.
> 
> What I did to set up my RX-320 was to let it achieve thermal equilibrium over
> several hours, and then zero-beat the crystal oscillator against WWV 15Mhz.
> This forms the baseline for the rest of the setup.  After reading your
> procedure it occurred to me that I could "tweak" Clifton's software in order to
> achieve good linearization from 60 kHz (WWVB) to 15Mhz (WWV). I followed your
> procedure in using the 1000Hz CW offset, and Spectran to measure the audio
> frequency
> to about 0.25 Hz. What I did a bit differently, however, was to first get the
> tracking
> "bang on" from 2.5 Mhz (WWV) to 15 Mhz (WWV). Then I checked 60kHz (WWVB). It
> was about
> 3 Hz out.  I found that by playing with the compensation values in Clifton's
> software,
> which allows you to enter decimal values for the compensation (ie -57.2 or 60.8)
> I could
> adjust the "slope" of the linear compensation to achieve excellent tracking from
> 60kHz
> to 15Mhz.
> 
> I did this just before Christmas. Today I checked the tracking again, and here
> are the
> results: (all error in Hz)
> 
> 15 Mhz +0.4 (WWV)
> 10 Mhz +0.4  (WWV)
> 5  Mhz  +0.2 (WWV)
> 60 kHz  -0.1  (WWVB)
> 
> Broadcast Stations (local BCB)
> 
> 540 kHz +0.9
> 580 kHz  -2.5
> 630 kHz  -1.8
> 740 kHz  0
> 
> The results from the local AM stations are interesting aren't they :-)
> 
> I should also point out that while doing the audio frequency measurement, I cut
> in a 1000Hz
> SCAF to prevent any interference from mixing products.
> 
> I think the key to achieving these great results is the AMRAD procedure,
> modified to make use
> of Clifton's software for the RX-320.
> 
> 
> 73's
> 
> Shaun
> 
> --
> Shaun P. Merrigan
> Edmonton, AB, Canada
> 53.55 N
> 113.47 W
> 
> 
> 
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