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  • Finland on 630m QRP OH8HTG plus 10Meters Also

    Using my Home Brew 10W PA and 6m x 6m Inverted L on 630m, ERP certainly no more than the indicated 10mW I got a new distance record last night.

    OH8HTG is 2051Km away.

    2014-10-25 00:20 G3ZJO 0.475771 -33 0 IO92ng 0.01 OH8HTG KP34di 2051 39

    OH8HTG is also active on 28MHz WSPR and doing a test with Horizontal and Vertical Antennas it seems. My 100mW WSPR on 28MHz uses a 5/8 Vertical antenna mounted on a ground post. Reception reports from OH8THG are consistently 3 to 4dB (sometimes more) up when he uses a Vertical antenna.

    2014-10-25 12:42 G3ZJO 28.126171 -15 0 IO92ng 0.1 OH8HTG/V KP34di 2051 39
    2014-10-25 12:32 G3ZJO 28.126173 -12 0 IO92ng 0.1 OH8HTG/V KP34di 2051 39
    2014-10-25 12:02 G3ZJO 28.126172 -15 0 IO92ng 0.1 OH8HTG/V KP34di 2051 39

    2014-10-25 11:22 G3ZJO 28.126172 -18 0 IO92ng 0.1 OH8HTG/H KP34di 2051 39
    2014-10-25 11:12 G3ZJO 28.126170 -26 0 IO92ng 0.1 OH8HTG/H KP34di 2051 39
    2014-10-25 10:12 G3ZJO 28.126172 -19 0 IO92ng 0.1 OH8HTG/H KP34di 2051 39

    It is nice to see such tests being carried out.

  • VLF Solar Activity Monitor - Correlation of Cause and Effect

    Today I spotted a smaller SID at around 09:45 UTC on my VLF SID Monitor it was possibly too small to trigger any e-mail alerts.

    In this instance it is interesting too take a look at the Goes Satellite Data, this shows us the cause.

    The plot from my VLF Monitor shows the effect.

    From the bottom :-
    Red Pen - Band Noise Increased.
    Black Pen - NAA USA Sharp Signal Strength Enhancement.
    Green Pen - 16.4KHz Noise Increased.
    Dark Blue Pen - GBZ UK Sharp Signal Strength Enhancement.
    Mauve Pen - FTA France 2dB Drop in Signal Strength.
    Light Blue Pen - DHO38 2dB Drop in Signal Strength.
    Orange Pen - GQD UK - Sharp 7dB Drop in Signal Strength.

  • Sudden Ionospheric Disturbances

    There has been an increase in Sun activity lately (Solar Flares) whilst it is nice to get e-mail alerts from observers and see captures of the effects from other Hams, it is nice to monitor them live for yourself.

    Yesterday I started my VLF SID Monitor and uploaded it to my VLF Grabber. After some tinkering I looked at my mail and sure enough there was a Flare just one hour before I started monitoring proper from then on the signals were flat.

    Well tomorrow / today is another day, so again I did some more setting up and ran a fast and slow version with some different stations monitored. There were at least two Flares overnight and early morning while my set up was off, so would I see anything.

    Yes at 15:02 local 14:02 UTC. The effects can bee seen in the Captures.

    Full recovery from this bombardment took around one and a half hours.

    I have prepared my VLF Grabber for the United Nations Day October 24, 2014 at 10:00 UTC SAQ transmission on 17.2KHz so I will be running daily until then. The message SAQ is at 10.00 UTC with tuning up from 09.30 UTC.

    Take a look at the Video put together by SolarHam.com which shows the GOES Satellite Data, predicted effects and video images of the Flare from different sensors.

  • Why do CQ WM50HTd Ceramic Filters Die like Flies

    I have had a run around with the CQ WM50HTd Ceramic filter which is fitted in the Motorola T3. Yaesu and other Ham Radio gear have trouble too with better known manufacturers offering.

    See my post Motorola TLKR T3.

    To me the Pattern of failure seemed to indicate corrosion. One poster on a forum had 3 out of 4 Radios fail between last use and the next switch on, some have mentioned electromigration others excess current actually causing fusing (like blowing a fuse) at switch on..

    I dissected the faulty filter.

    Only at one end there is a copper / phosphor bronze pressure plate with windows in it, the silvered plate adjacent has verdigris on it from the copper one.
    Hmm, corrosion inside a hermetically sealed box ? Rubbish sealing by a rubbish manufacturer more like, plus maybe contamination in the manufacture.

    I was not gentle in my opening of the filter I was expecting a hard plastic box so I crushed it in a small vise. This revealed that they had used a soft thermoplastic. This may well explain the breaking of the hermetic seal. SV8YM see below was more careful with his dis assembly he says the pressure plate "keeps everything pressed together when the filter is in its case" that pressure on a soft thermoplastic box will cause the side to bow thus opening the filter to moist air and removing the pressure required for it to work. There is a common factor in the filters taken apart, verdigris on the copper plate. Additionally I think the seal is breaking at this end.

    Soft thermoplastic housings are a real pain. From the humble 4 cell battery holder where the cell sticks in the molding despite the spring pressure behind it and the plastic at the positive end moves away, to my Alinco hand held, the accessory 6 cell battery holder gradually took on a bowed shape due to fat NiMH cells and finally split. Maybe I have the only metal clad cell holder, my way of extending its life.

    Idiots in manufacturing is not limited to Electronics, a 600 caravan roof vent has a winder mechanism to raise and lower it. The winder drives cogs which mesh into a Bowden cable type worm, the cable needs to be pressed against the cogs so the manufacturer molds a dome on the inside of the gearbox. The gearbox is soft thermoplastic so in a very short time the side with pressure bows and the cogs slip. With that we have a gap open up on a grand scale 3 to 4mm wide.
    What ever happened to the proud designers and engineers, things could still be made cheaply using proper materials.

    I found more information on the subject of filter death after my dis assembly, it is interesting to find that SV8YM considers it is electromigration, he has found consistently that the filters show a measurable resistance leak to earth. My one instance measured truly open circuit and all ceramic elements and plates were almost clean except for the odd tiny spot of corrosion on the metal plates. The copper / bronze spring and the adjacent plate are clearly the originating place of corrosion.
    In my instance the thick ceramic plates only have a small circular silvered contact area on either side, no chance of corrosion salts shorting across the edge of the plate with those.

    There is also a theory about applied voltage causing problems, I have no circuit for the T3 so I don't know if there are DC blocking capacitors. Actually there is no need for an external voltage, we have a dissimilar metal cell with the copper plate and its adjacent one which can generate its own voltage when the radio is off, the T3's spend more time off than on so they decay due to electrocorrosion in storage, ready to be dead when needed for use.

    Two simple things would certainly help make more reliable filters, a long spring clip made of a non dissimilar metal across the whole stack.
    Or a non dissimilar metal version of the present one and a rigid plastic box with the base heat welded for a reliable seal.

    I was surprised when looking for a UK supplier by one of the distributors terms and conditions of supply for ceramic filters. Prospective purchasers had to sign a declaration that they were not for use in any application where reliability was critical. Obviously all is not well in the ceramic filter world. The more you look the more you find out that is so.

    Read the interesting story from SV8YM here Withering Filters.

  • One of the Mothers of WTV's on 2m WSPR

    Some of the first comments made about screen grabs reported to be showing WSPR Wing Tip Vortex Reflections was that this is an AGC effect.

    I have not before found a signal on 2m strong enough to pump the AGC on my Kenwood TS790 until today when my mast was up and I turned my beam on G3XJV just 46Km away who was running 100 Watts.

    Note the common start shift of the artifacts with two adjacent WSPR periods (marked with orange lines) there is a 2minute TX period between these two transmissions, any external effects (WTV's) from Aircraft would have carried on in the same direction or faded away not restarted with the same shift at the start of the next transmission.

    G3XJV was a good 0dB signal on the back of my beam and as I was beaming across the N/S UK corridor there was much Aircraft Scatter no less than 12 separate planes at one time.
    I turned my beam toward G3XJV and his signal is between +4dB and +13dB.
    I can hear the AGC pumping and captured the effects.

    In an impromptu test, was G3XJV watching my Grabber, he dropped his power to 2W the same level as mine and the 'WTV's' were no more.

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