[Elecraft] Harris Channel 11 VHF TV Amplifier Modules - IMMEDIATE ATTENTION REQUIRED

[AD6XY]

I have two of these sub modules. They will convert to 144MHz with a little
effort and some small expenditure on 25 ohm coax. They make great
amplifiers, I have one modified and run it up to 400W output on 144MHz, but
you will need to keep spares as the PA devices are custom. Of course they
would work unmodified on the 220MHz band and maybe that's the best option.
The trays of 4 modules make 1500W.

A note of caution, I paid about $200 each for mine and at the time it was a
very good deal. I was intending to combine them to make an 800W amplifier,
but then the MRFE6VP61K25H design appeared in Dubus. With that design you
have nearly 1kW linear output from one device for not a lot more money than
I had paid for two modules and without any of the fuss of combining them or
the potential lack of spares should a device fail. Jim, W6PQL makes kits for
the MRFE6VP61K25H and I suppose its about $600 to get you to the same point
you would be with two Harris modules.

So, although $600 is a lot more than $400. all of the casing, filtering,
protection, TX/RX switching and so on still needs to be done for either
amplifier. Once you build it you realise the power module is only half of
the job and you need to budget another $500 to finish the job, the saving
from surplus modules doesn't look so attractive. 

Where it is attractive is if you need much more power than the 900W you can
get from the MRFE6VP61K25H, say for EME running a high duty cycle mode like
JT65. Then 8 modules will give you a "conservative" 1500W at the feed. It
makes more sense for one or two people to get together and take all in one
go.

Always a pity to see nice RF hardware scrapped.

Mike G0MJW/AD6XY



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