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From: "Mike Dennison" <mike.dennison@ntlworld.com>
To: rsgb_lf_group@blacksheep.org
Date: Thu, 24 Oct 2013 17:09:43 +0100
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Subject: LF: 74kHz - history
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Status: O

Bob, here is a potted history of the UK 73kHz band:

The  long term plan was always for a long-term international 
allocation. This was going to take some time and so an interim 
allocation was negotiated by the RSGB at 73kHz. This was shared with 
some VERY loud commercial stations. Special permission had to be 
requested to transmit, and the few of us who operated portable had to 
specify when and where we would do it. As with your work, amateurs in 
various countries participated by giving reception reports.

Later, the plan for an international allocation bore fruit, partly 
because of our work on 73kHz demonstrating that amateurs would be 
very unlikely to cause problems to commercial LF users, and we (and 
others) got the 136kHz band. Most activity shifted to that new (and, 
as you have found out, much easier) band, though several of us 
continued with experiments on 73kHz from time to time. The 73kHz band 
was eventually removed from UK amateurs following a change in the 
commercial use of this part of the spectrum.

It is to be hoped that the work of you special licensees on 74, 136 
and 472kHz will eventually lead to some full LF/MF allocations in the 
US.

de Mike, G3XDV

> Mike;
> Interesting indeed.  When you operated here was there a push by the UK
> ops to move to 137?  How did that come about?  RSGB influence to move
> to 137 and just give back 73?
> 
> > From: mike.dennison@ntlworld.com
> > To: rsgb_lf_group@blacksheep.org
> > Date: Thu, 24 Oct 2013 16:11:00 +0100
> > Subject: RE: LF: 74kHz - WG2XRS/5 callsign at last (2of2)
> > 
> > Oh yes. But it is a little early in the year and it will reduce as
> > it does on the other low bands, with some zero static days. When we
> > had the band some years ago, we were mostly using CW and QRSS3 over
> > shorter distances (my record was about 1100km) but we tended to
> > operate early in the morning when the static was at its lowest.
> > 
> > I reduce the interference here by using the quite effective noise
> > blankers in my Afedri SDR receiver, together with lots of fast AGC.
> > Then heavy limiting and a further noise blanker in SpecLab. The
> > resultant 'holes' are small compared with the QRSS60 bit length. 
> > 
> > de Mike
> > 
> > > Mike;
> > > Is that "pesky static" a characteristic of this band-from your
> > > passed experience?  
> > > 
> > > > From: mike.dennison@ntlworld.com
> > > > To: rsgb_lf_group@blacksheep.org
> > > > Date: Thu, 24 Oct 2013 15:30:14 +0100
> > > > Subject: Re: LF: 74kHz - WG2XRS/5 callsign at last (2of2)
> > > > 
> > > > Well, Dex that was the good news. The bad news is that, as I
> > > > cautioned earlier, the lower noise level lower in the band was a
> > > > function of my antenna pass band, and not of absolute noise. I
> > > > re- tuned to a lower frequency and it wasn't any better. So the
> > > > current frequency seems as good as any. 
> > > > 
> > > > Interestingly, I left my SDR plotting a few kilohertz around 74k
> > > > last night with long integration and I could see the shape of my
> > > > antenna passband produced by the night-time static acting as a
> > > > broadband noise generator. At last, I have found a use for that
> > > > pesky static!
> > > > 
> > > > de Mike
> > > > =======
> > > > 
> > > > 
> > > > > Mike Dennison wrote:
> > > > > > More pics including the XRS/5 caps.
> > > > > Thanks Mike!  That's a keeper.
> > > > > 
> > > > > Dex
> > > > > 
> > > > 
> > > > 
> > > > 
> > > 
> > 
> > 
> > 
>