From: "Mike Dennison" <mike.dennison@rsgb.org.uk>
Organization: Radio Society of Great Britain
To: rsgb_lf_group@blacksheep.org
Date: Thu, 7 Oct 1999 10:08:04 +0100
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Subject: Re: LF: 73kHz - bad news
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G2AJV wrote:
> Thank you for the possible explanation of the 73 kHz blackout.  I wonder
> if Rugby may have started to use spread spectrum in parallel with its
> normal system. 

Funnily enough, that is a possibility that Peter, G3LDO, and myself 
were discussing this morning. The noise appears to decay fairly 
linearly with frequency, whereas I might expect it to be more 
exponential if it were oscillator sidebands.

> I then climbed
> the ladder to adjust the situation when suddenly the ladder slipped and I
> travelled in a beautiful arc, landing on my shoulder, then my head and
> finally the rest of me!  No real damage - just a bit of a headache,
> stiffness and aching but I got a severe ticking off from my wife.
> I'll have to sneak out tomorrow but will not be able to do any tests
> before about 11 a.m.

Take care!!

>  From what you say about Rugby , Mike, it seems that all the
> overhauling that I've been doing on my rig for the past few months may
> have been a fool's errand.  Your report on the very high background noise
> level makes much more sense but was completely unexpected. 

Hmm, you may be right. I'm not sure when the noise level increased 
as I had not been on 73 for a few months but I was puzzled that 
G0MRF received me so weakly a few weeks ago.

>         I will try to ensure that my system is on top form for the H.F.
> Convention on Sunday morning but, after the experience of the last few
> months, and especially the last few days, I do not anticipate much luck.

I will take my crude but effective 1m loop antenna with me in case 
that helps the convention station on 73.

I am determined to have some more QSOs on 73 before we lose it 
so will concentrate on noise reduction by (1) directivity, (2) 
cancellation and (3) DSP. In the meantime, we need to use 
frequencies as low as possible.

The experience of the convention station may be useful in 
determining what (and how bad) the problem is.


Mike, G3XDV (IO91VT)
http://www.dennison.demon.co.uk/activity.htm