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MFJ Cub QRP CW Transceiver

The MFJ cub 9315K is a lightweight and very compact 1W QRP CW transceiver for the 21MHz band. When I bought mine, it was supplied as a semi-kit with the SMA parts ready assembled but with the discrete components and pre-drilled mechanics left to assemble. There is no wiring as such apart from winding a couple of toroids. The whole finished job looks very professional. Versions are available for most HF bands. The designer was Rick Littlefield, K1BQT and a great design it is. The picture on the left is my version when finished building.

In all, about 3-4 hours of building and alignment gives you an excellent little QRP station. The only problem I had was finding the VFO frequency at first during alignment as one can easily miss this when tuning the inductor slug. Once found, the rest of the alignment was easy. The only equipment really needed during alignment are a general coverage receiver and a voltmeter.

The receiver is a sensitive and selective superhet well suited to 2-way QRP working. The combination of a sharp crystal ladder and peaked audio filters is highly effective. Band coverage is approximately 50kHz, VFO tuned and there is very little drift after a short warmup period when running from a stable 13.8V power source. Power output on TX is adjustable from just over 1W to milliwatts. There is off-air sidetone and smooth full break-in. The only controls are VFO, volume and on-off. An IRT would have been nice but I haven't missed one so far.

Like most radios, there are modifications around on the net to enhance the performance still further. Some people have reported drift problems on some versions but I've not noticed this on mine from a stable supply.

My honest view is that this is one of the most fun radios I have had in 40 years of ham radio - that's how much I like it!  This little unit has given me many hours of pleasure on 21MHz with best DX being a YV in South America at 8000 kms with just a low wire dipole in the back garden. Typical reports are RST559 with the best RST599 - but the worst so far was given as RST209.