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Saturday, 4 October 2014

Finalising the Conundrum....

Well,

A few things to report....

Firstly, when I was at the National HamFest the other weekend, I found myself a signal generator. It's a HP8648A and looks like this:


It covers 100KHz up to 1GHz and appears to be calibrated in agreement with my Spectrum Analyser. That's good enough for me and at last I have a Signal Generator where I can specify the output amplitude in dBm!

I've been fiddling today with the transverter project I started back here:

http://g0mgx.blogspot.co.uk/2014/09/to-transvert-or-not-to-transvert.html

and have been making the final component which is a 10W PA to give a reasonable level or RF out. Here's what the PA looks like:


It's based on a 2SC2539 final transistor which is mounted on a reasonable heatsync between the two copper boards you can see. The PA seems to be working with a nice clean output:


The driver transistor (which is a poor old 2N3866) is running hot, hot, hot! I need to find a better component for that bit as otherwise it's going to cook. Something with an isolated can would be ideal so I can solder it to the copper board - that would make an excellent heatsync.

I've stuck the project together now and it's looking like this:


I need to run some more tests on the output to check for harmonics and other spurious emissions, but I think this is good for an on-air test now.

The only other thing to report is that I left my FT-DX3000 WSPRing on 40M last night, I set the RF out to the lowest setting (5W) but also reduced the audio drive so the output was reading 2W on the internal meter. This is the map of heard/hearing this morning:


Florrie cat's not been helping much, sleeping behind the radio PC monitor:


The other three spent most of the afternoon upside down in the kitchen:


Good, egh?

Local conditions.

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