Tuesday, 24 June 2014

Plumbing the Anglian

I wanted to use my Anglian 144MHz  transverter with my ICOM Pro3, as the 28MHz IF. The problem was that the Anglian was designed with a K3 in mind so has separate transmit and receive IF ports.
Since the Pro 3 only produces around -20dBm IF output (typically ICOM) there was also the problem of  whether there would be enough IF drive, especially with another 3dB loss due to the MiniCircuits IF coupler.
The first tests were encouraging when the receive noise level came up significantly on the Pro3 when the transverter was connected and the transverter port activated.
I found I could get about 40mW 2m out of the Anglian with full -20dBm, 28MHz drive. Removing the two  parallel 120R dump resistors and placing a 10R across the 100R in the input attenuator I could bring the 144MHz output power back up to 100mW. As the Pro 3 transverter output is quoted in mV I assume the output impedance it wants to look into is not necessarily 50R?
100mW of 144MHz IF is just sufficient to get to about 7 W output from my 10GHz transverter, with the current setting. When I next take the 10GHz off the mast or luff it over, I will increase the transmit gain to compensate.

I'm now looking forward to the UK AC on 10GHz this evening. I'm also hoping Englnd will have won their last World Cup match as well!

Sam

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