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RE: LF: Re: WSPR/Questions

To: <[email protected]>
Subject: RE: LF: Re: WSPR/Questions
From: Laurence BY3A-KL1X China <[email protected]>
Date: Mon, 7 Sep 2009 06:26:54 -0800
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Thanks Jim - good work on the antennae - I love them Cherry pickers ! as for 504 - I dont know as I havent looked into it very deeply and it must be a common issue but even on the smallest near efficient antennae we see tram lines; as you say and in my case they could be a mix of local artifacts - that wouldnt suprise me at all as I have 100 neighbors all within a 100m horiz and vertical distance -  but thankfully the antenna sits outside a virtual Faraday cage as most of the reinforcing of the building is holding and dumping  the QRM inside the "box" - if I dont ground the coaxs before entry the QRM sits over S9 plus - with it S4/5.
Im game for WOLF at any ones convienence and just cal'd the decoder using the 30 over signal from 60/68.5/39kHz and moreover 10Mhz to tweek the inductor and stab Osc in the R75.
Thanks for the signals - all very interesting. Long Haul - and Eu is definately that, werent so good last night in general and I noticed more attenuation at LF/MF on the remote Alaskan receiver too.
LaurenceTanggu Tianjin China

> From: [email protected]
> To: [email protected]
> Date: Mon, 7 Sep 2009 14:02:26 +0100
> Subject: LF: Re: WSPR/Questions
> Dear Laurence, Roman, LF Group,
> I shut the beacon down at 0446utc this morning. The frequency was 503.975kHz
> as advertised. Thanks for the overnight reports, nice to see spots from
> W1TAG again and from Russia for the first time. I transmitted in about 75%
> of the 2 minute periods between about 1940 and 2050utc, but saw nothing like
> a signal in the BY3 grabber, although the frequency seemed mostly clear.
> Conditions were relatively noisy here with more QRN than the previous night.
> The antenna is a top-loaded vertical with 3 wires in a sort of Y shape in
> the horizontal plane. Where the wires meet, it is supported by a 10m
> fibreglass mast. To "jack up" the antenna, I have an old "cherry picker" (or
> aerial access platform or whatever you wish to call it) which is slowly
> sinking into my lawn. The bottom of the mast is bolted to the cherry picker
> where the operator's basket used to be, so the whole mast can be raised into
> the air. This allows a total maximum height of about 19m if I am feeling
> brave; last night the middle of the antenna span was raised to about 17m.
> Previous FS measurements have shown this gives about 3 - 4dB improvement in
> ERP due to the increased height and radiation resistance, along with a
> slight reduction in loss resistance. The total length of wire in the antenna
> stays the same, but gets further from the ground, so antenna capacitance
> actually reduces slightly. The things we do to try and get a better
> signal...
> Cross-band QSOs from M0BMU are unfortunately difficult at the moment due to
> the high QRM levels on the lower HF bands here - I am hoping some work on
> dedicated HF receiving antennas here will improve this soon.
> The 504kHz signal seems to be present in many widely-seperated QTHs - don't
> know about W/VE though? It seems to be different at each location. Here it
> is a rather weak carrier with no audible modulation, on the spectrogram it
> can be seen to have a couple of stronger spectral lines and several weaker
> ones spread over a range of a few Hz. These seem to vary over time, possibly
> due to QSB. They can't all be RTE/Atlantic 252 harmonics - 504kHz is an
> integer multiple of 9kHz, so many opportunities for internal or external
> intermods due to broadcast stations. 504kHz is also a multiple of 8kHz, as
> is 136kHz - it was suggested at one time that the weak carriers audible in
> many places on 136.0kHz could be harmonics of the 8kHz clock rate used in
> wired telecomms.
> I would be quite interested to try WOLF again - although it needs more
> careful coordination with frequencies than WSPR.
> Roman, there are some pdf files on the UK 500kHz group site about some of my
> LF/MF gear - you are welcome to use those if you like.
> Cheers, Jim Moritz
> 73 de M0BMU

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