Friday, May 08, 2009

JUMA goes home

Last night I had an email from Gerd, DF9TS, who had returned from his business trip and wanted to know if I had managed to finish my evaluation of the JUMA TRX2 transceiver, and was I planning to keep it. I told him that I had enjoyed trying it out, I really liked the sound of the receiver, but I found numerous little annoyances with it.

The filtering is not very flexible, with only three filter widths for all modes. And with the lower filter edge fixed in position, you can't choose the centre frequency for CW or data. Although the receiver has been designed to give exceptionally high dynamic range, the AGC can't be turned off, so you still lose a weak signal that's close to a strong one.

No provision was made for data modes in the original design, and although the JUMA community is developing mods to provide this facility, it is still a bit of a kludge, as it was for the Elecraft K2 (which at least had the excuse that it was designed in 1998 before sound card data modes took off in popularity.) There are also questions as to whether the PA and driver components are adequately heat-sinked for high duty cycle operation such as data modes.

Gerd probably sensed that I was a bit luke-warm about the JUMA, and replied that I should feel under no obligation to keep the radio if I didn't really want it. During successful QRP /P operations while on his trip, he had changed his mind about buying an FT897 which had been his reason for wanting to sell the JUMA in ther first place. So I have decided to send it back to him. I will, of course, pay for the cost of sending it to me in the first place.

I am very glad to have had the opportunity to try the JUMA TRX2. It is still a very nice radio, especially if you are an SSB user (or even CW, if you can adapt to having a spot frequency of 400Hz to get the narrowest filter.) But I am spoiled with the K3, plus too many other QRP radios, for it to be worth buying given the shortcomings I mentioned.
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