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Re: LF: RE: 600m Info

To: <[email protected]>
Subject: Re: LF: RE: 600m Info
From: "Graham" <[email protected]>
Date: Thu, 24 Jul 2008 23:14:27 +0100
Importance: Normal
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]>
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Some thoughts on 600

The antenna systems and power levels needed to establish communication on 600 Mtr's are considerably smaller than 2200 , the tx power levels are compatible to normal HF operation , in tests , 20 watts feeding a 35 ft top loaded system , using modern and not so modern data systems have produced reliable copy both inside the apparent ground wave range of 60/70 miles ( A un expected phenomena resulting in 'beacon bedlam' a testing time south of Watford gap ) and in the intermediate skip ranges of 250+ and 500+ miles.
5 or 10 watts , giving a good trace at Johns most excellent internet linked
panoramic monitoring station located in the Shetland islands , some 600
miles north of my qth , which at the moment can be observed a on going
propagation experiment by Finbar with compact antenna array, slightly
closer (to me) is of course I think the original monitoring station
established by Dave in Birmingham , which has proved invaluable as a remote
monitor for those in ground wave range , some 500 mW being all that is
required to produce a trace
It is tempting to replicate vlf systems and launch them on 600 mtr , but in
retrospect this might of been the result of operations rising from the lower
bands and not , dropping down from top band, where it would of never
occurred to any one using data to of deployed a non linear system, even
with the deployment of the 'wspr' auto reporting beacon system, still
requires either the use of a pic controlled dds exciter or the linear
translation of the sound card interface. linear translation in frequency
that is , to retain the very narrow fsk
The generation of power levels round the 100 watt , may be accomplished by
any of the existing technology's and where it is quite possible to obtain
high levels of efficiency with non-linear systems , in the long run the
limitation this imposes on the types of modes that may be used, may, if
taken into account at the off set , may of resulted in a much higher take

The only advice I would give is , If you can use top band , then you can use 600 , you don't need much power and keep your options open , keep it linear ... this opens up experimentation using all most anything ...


However If you have introduced logic in the transmitter drive chain , this rather well presented project by 'Jim may facilitate a change of mode?

Link's  :-

Reference material listed on the EER transmitting page of the uk500khz news group.
From: "Gary - G4WGT" <[email protected]>
Sent: Thursday, July 24, 2008 8:37 PM
To: <[email protected]>
Subject: LF: RE: 600m Info

Steve, LF,

Re: "Scopematch"

I built the "LF Tuning Meter" from Jim M0BMU for 136 KHz & I now use it for
500 KHz & it works just as well.

Quoting from the article :-

"This LF tuning meter was conceived to perform the same function,
but to be a simple, self-contained unit requiring no additional power

Gary - G4WGT.

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Steve McDonald
Sent: 24 July 2008 18:59
To: [email protected]
Subject: LF: 600m Info

Are there any web sites devoted to 600m circuits etc? I am aware of the U.S.
group one as well as G3YMC's page and N4ICK's tx design, but perhaps there
are others as well?

Several of the 2200m experimental licencees have just been asked to submit
formal proposals for 600m experimental permits here in Canada so things are starting to look positive but I have no idea of the timeline. Just in case, I thought I had better get the soldering iron warmed-up once again, not that
it has ever really cooled-off.

Also...does anyone know how well the M0MBU scope match circuit (that works
so wonderfully-well on 2200m) performs on 600m without any modification?

Steve / VE7SL


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