[amsat-bb] Re: QSO through ISS

andy thomas andythomasmail at yahoo.co.uk
Fri Jan 16 00:38:29 PST 2009

Hi Gordon,

many thanks for the qso. Your handheld effort was significantly better than mine and I appreciate your qso discussion and signal report. I'll be delighted to exchange cards if you would like to - and of course you can now claim the 25th anniversary ARISS certificate as CONTACT (REPEATER) with the ISS! Not bad at all for 5 watts handheld!

The reason I asked you about the audio was this. I was using a doppler corrected system using Ham Radio Deluxe which depends on accurate and up to date kepler elements. This was producing really bad audio on the receive side and after talking to you I realised that the problem was that the ISS had reboosted its orbit - but this had not been refelected in the keplers used, even though I had forced a reconnection to the celestrak server. (Incidentally the AMSAT on line predictor had earlier given the same times for AOS and LOS) So the ISS was "late" in terms of the predicted and my doppler system was not tuning correctly to the downlink, hence my receive audio problem. After talking to you I retuned manually up in receive frequency but alas! too late to make another qso.

My friend Colin G1IVG had the same problem and when I reported it on the amsat bulletin board Sebastian W4AS reported the same thing.

Because you were manually correcting for doppler, you beat the machine!  you were tuning by ear in 5khz steps on the Kenwood and it worked properly.

So many thanks for the qso, it allowed us to figure out what was going wrong and to alert stateside via the amsat bulletin board. and the iss fan club site.

I hope you don't mind but I'm copying this whole correspondence to the amsat-bb to celebrate the contact and what we learnt from it.

73 de andy G0SFJ

--- On Thu, 15/1/09, Gordon JC Pearce MM3YEQ <gordonjcp at gjcp.net> wrote:

> From: Gordon JC Pearce MM3YEQ <gordonjcp at gjcp.net>
> Subject: QSO through ISS
> To: g0sfj at amsat.org
> Date: Thursday, 15 January, 2009, 11:58 PM
> Hello,
>   Thank you for the brief QSO through the ISS repeater. 
> It's the first
> time I've ever had much confirmation that I've
> actually got into it.  I
> can hear it quite well even with a rubber-duck antenna on
> my handheld -
> even my el-cheapo Jingtong JT308 - but so far I haven't
> seemed to get
> any contacts through it.
> I'm in IO75tv square, Glasgow.  The ISS is pretty low
> on the horizon
> here for most passes, at best around 35 degrees.  I'm
> running 5W from a
> Kenwood TH-F7E handie into a homebrew dual-band cross
> dipole, with three
> elements on 2m and five on 70cm.  For something that took
> an hour to
> build, it works fairly well ;-)  The whole thing is
> entirely handheld in
> my back garden.  It feels like a bit of a cheat to say
> "portable" when
> I'm literally standing outside my house, but it really
> is a portable
> setup.
> Your audio was very good through the ISS - better than my
> local 70cm
> repeater usually is.  I think I may need a bigger 2m
> antenna, or a bit
> more power - I've got a 2m 6-element quad which I might
> press into
> service.
> Anyway, maybe I'll catch you on another pass
> 73,
> Gordon MM3YEQ


More information about the AMSAT-BB mailing list