10 Aug 2014

A close call (storm) and 472kHz WSPRing again

The thunder and lightning just missed us today. We had heavy rain, hail and thunder but the lightning missed us by a few miles. It is now out over the North Sea.

About to reconnect rigs, antennas and PC. Think I'll give 472kHz WSPR another try.

UPDATE 1644z:  Now back on 472kHz WSPR and rewarded with spotting G3WCB immediately and being spotted by 3 stations on first transmission including M0LMH (223km) as a new reporter this season. Will stick on 472kHz until morning unless more storms stop play.
Initial WSPR spots this evening on 472kHz
UPDATE 1730z:  Currently reading "The Everything Store - Jeff Bazos and the age of Amazon" by Brad Stone, lent to me be a neighbour/friend. Fascinating read about the history of Amazon. Bazos sounds like the boss you would NOT want - a real taskmaster - a very "driven" man with real conviction.


Martin G7MRV said...

Hi Roger,

Whilst waiting for the storms to pass, I 'revisited' the 10m 'Wispy' I am building - Finally having some success!

It seems, all along, that I simply wasn't driving it hard enough! I now have it sat on my shack desk, running roughly 200mW DSB to my main antenna. No spots yet (but wasn't having any luck on 10m with the main radio either!) but can pick it up and decode it ok on my main set-up.

I'd like to swap the 2N3866 PA for a 2N3904 strip, I'm thinking of trying 8x Q's to try and get 500mW SSB equiv.

If you dont mind, could I ask - what would you suggest for the emitter resistors in such a strip? and, would you change the bias resistor values?

Looking forward now to completing the receiver side!

Roger G3XBM said...

Hi Martin,

The cheap 2N3904s work well as a PA. I think there 3-4 in mine. For emitter resistors I think something like 10-15 ohms in each should be OK. It might be advisable to put a couple of larger values in parallel in each emitter if rating is an issue. Of course with 2N3904s at about 3-5p each if you blow up any it is cheap to replace them. There is something nice about doing it "on the cheap" too. I love 2N3904 transistors and use them in all sorts of circuits.

I have built the RX and TX separately, but still to combine both due to my poor health currently. You may recall I had a brain bleed last September. Another project on the "to do when better" list. Currently I am very clumsy, making all building all but impossible, for now. At least I am mending, albeit slowly.

Martin G7MRV said...

Thanks Roger, yes I was thinking around 18 ohm or the like. Ive bags of them so like you say doesnt matter if a few get fried.

Im also going to put a 7- pole LPF on to help knock the harmonics down.

Its good to know your on the mend Roger, Im sure you'll be burning solder again soon