6 Mar 2014

Sunspot count over 200, VLF earth-mode, and my stroke

Today I have taken a day off from 10m, but I see the sunspot count is 202 and the transatlantic path is well open with lots of EU stations being spotted in the USA and Canada, and vice versa. There are good spots from Europe to S.America too and the band was open EU to Australia again this morning.

VLF  earth-mode beacon TX
Later today, if my energy levels improve (very low currently because of my stroke after-effects) I want to match my 8.97kHz VLF earth-mode TX  into the earth-electrodes better. At 472kHz they look quite a bit different here compared with at the old QTH (here more like 200-300 ohms with some capacitive reactance whereas at the old QTH it was more like 40-60 ohms resistive. At VLF it might be a lot different, of course. My initial earth-mode VLF results from this new QTH last August/Sept (before my stroke) were disappointing and this may have been due to poor matching?

If I can get more power into the ground I may ask my wife to help me with some drive tests locally to check earth-mode VLF performance. This is where I REALLY miss my health and fitness. I tire SO easily at present, but have been told this should improve given time and more healing.

Guess I have to slow down and let things take their time and not expect instantly to get better. Apparently I was VERY poorly last autumn - my heart stopped at one point and the first 4-6 weeks in hospital are just a blur -  and feel I am almost living a new "second chance" life. Certainly I have never seen a more beautiful springtime.

UPDATE 2045z:  In the end the VLF work will have to be later as I am too tired right now. The simplest way of increasing the output impedance is probably to reduce the PRIMARY turns on the 3C90 output toroid s long as the frequency response is OK. This is currently set for a 4:50 ohm step up. Reducing by a few primary turns may be all that is needed. We'll see tomorrow.

3 comments:

Ken May said...

Hi Roger,
Do you want to try WSPR-15 on 8.97KHz? I could report back on WSPRnet.
73 Ken G4APB

Roger G3XBM said...

No thanks Ken.

Tests with a very stable carrier over a 30km range proved negative. I am essentially just testing earth-mode range compared wit the old QTH. Unless within20km of Burwell I think we'd be wasting our time at this stage.

73s Roger G3XBM

Ken May said...

Ok Roger,
I have set up my gear to listen out anyway, as it is a useful exercise for me to be sure I can still run the tranverter and amplifier with WSPR-X mode and the 15 min cycle on an RX-TX cycle at 8.97KHz. I am running with my earth rod and ground based Magloop system that worked well on 474KHz. You may see my attempts on WSPRnet on the 'LF' band. I did wonder if the 20 metre raised water table after the floods may assist earth mode. Best of luck with your tests and hope your health lets you get some fun out of it.
73 Ken.