Wednesday, February 25, 2009

K3 Transverter woes

A few days ago I decided that I would make the most of my Elecraft K3 by using it on 2 metres as well with the aid of a transverter. I was wondering what one to get, probably one from Spectrum Communications as all of the others on the market are very high end with price tags to match. The Elecraft transverters would have been the obvious choice but they are also quite pricey, styled to match the K2 not the K3, and have inadequate heat sinking for FM use which is my main interest on 2m.

The decision was made when I saw a Spectrum Communications transverter advertised on Junksale.co.uk by Mick, G6HUP at a very good price. It arrived today, so securely packed it could have survived being thrown out of an aircraft! It is in very good condition and works very nicely indeed. Thanks, Mick, you are a great guy to deal with!

Unfortunately after connecting it to the K3 I found more of the problems that have made ownership of this radio so frustrating. I could receive on 2m OK but could not transmit, and when I checked the K3 was producing no RF output.

The transverter I bought is designed to be used with a radio that has no special low level transverter output, which my K3 hasn't - it's a $99 option. The K3 has special transverter ranges that can be configured either to use the KXV3 transverter interface, if you have one, or else the normal antenna socket with higher power. I set up the K3 for the latter option, but it became clear that it was still behaving as if the KXV3 was being used. By chance I discovered that if I toggled the KXV3 option in the configuration menu to "installed" and then "not installed", it would work as requested and produce the 5W output my transverter needed. But as soon as I changed bands or even recalled a frequency from memory it would forget this setting and I would have no output again.

Having found the workaround for this obvious bug, I then stumbled on the next problem. The K3 would refuse to transmit if the receiver was tuned above 145.700. It displayed the "out of band" warning. I guessed that the problem was occurring because the upper band limit of the 10m band (the transverter's IF) is 29.700MHz. But it occurs even when the repeater offset is selected and the transmit frequency is 600KHz lower and well inside the 10m band. Because of this I can't use one of the two local 2m repeaters!

I dare say Elecraft will fix these problems. But it is extremely annoying to keep coming across such basic faults on a radio that cost this much money. The K3 would be a fine radio, but its firmware is only half thought out, poorly written and inadequately tested, and I'm tired of being a beta tester.
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