Friday, 15 August 2014

Wispy On Test - Fingers Crossed!

My 10m 'Wispy' is now on receive test. It took a bit of time to work out usable level settings for the laptops microphone input, but im now showing the correct 0dB noise level, which in this case is a mic level of 50 and a 20dB 'Mic Boost' setting. Unlike when using a normal rig, where no mic gain is needed, the receiver here is very basic and the levels very low.

All I need now is an actual signal in band at a level strong enough to decode, or at least, see on the waterfall! But conditions have been very poor recently, with no spots even using commercial equipment, so this could be a long wait.

I also, have as yet not aligned the receive chain with a test set signal. Theres only two trimmers to adjust, but I dont want to tweek them yet. Save that for the Marconi 2955! For now, I'll just soak test the unit, check no smoke comes out anywhere.

In the meantime, I cannot use the main station for any HF work, since Wispy is on the main antenna! So, Ive moved back onto 6m to see what if anything might be doing in JT6M

UPDATE: Well, not a single spot received. I suspect that the band is pretty quiet anyway, which makes things harder when testing 'on-spec' like this.

However, I do know that the receiver works, at least after a fashion. The main station antenna is directly over the workshop. So, with the Wispy set up on receive in the shack, Ive set up my Marconi 2955 communications test set to give a signal on 28.1246MHz, with 1.5kHz modulation. Unfortunately, Im not lucky enough to own a test set that can produce SSB, so its a 45% modulation AM signal, and the maximum RF levelis 5dBm, into a telescopic whip. This is however just enough to detect as an AM envelope on the WSPR software!

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