There are four antennas in the MFJ screwdriver range. All of them are supplied with two extendable whips. One whip is 10’ long, which collapses down to about 18”, and intended for portable or stationary mobile use. The other is 4.1/2’ long , which collapses down to about 28”, intended for mobile use. The difference between the four models available is the length of the coil, the longer the coil, the greater the frequency coverage. All coils are 2” diameter. The four different models are as follows:
MFJ-1661: 12” coil. Covers 6-20 with the small whip. Covers 6-40 with the large whip.
MFJ-1662: 15” coil: Covers 6-40 with both the small and the large whip.
MFJ-1664: 24” coil: Covers 6-40 with the small whip. Covers 6-80 with the large whip.
MFJ-1668: 36” coil: Covers 6-80 with both the small and the large whip.
The model I have is the 1664. I have used the antenna both stationary mobile and portable, but not mobile with the small whip. All the comments in this review are with the 10’ whip. For use on 10 and 12 metres, the whip is used on its own and the results are covered under a separate review.
To use the antenna, you will first require a 3/8” mount, plus a suitable ground plane/counterpoise. As with all quarter-wave vertical antennas, a good ground is imperative for good results, details can be found in many publications both for mobile and portable installations. If you do not use a proper ground system, the antenna will not tune properly and results will be poor. For my mobile, I use a mirror mount on the luggage rack, grounded to the car body. For the portable, I use a buddistick tripod with wire radials. If possible, I try to use a fence or similar counterpoise for better performance.
To tune the antenna:
On 15 metres, when the (fully-shorted) coil and 10’ whip are put together, the length is just a little longer than a quarter wave. Push the whip in 3” or so, and it should be fine.
On 17m and lower, you will need to use the coil. The amount of turns is achieved by raising or lowering the outer sleeve over the coil. I find that 3 turns is sufficient for 17, 7 for 20, 17 for 40, and 80 is tuned “by ear”, depending on the band segment. The instructions suggest using an SWR analyser, but if you don’t have one, checking with an swr meter is quite simple and quick once you master the technique. The instructions also mention that a shunt coil may be necessary to obtain a low swr, especially on the lower bands, however I have not found this to be necessary.
Now, the million-dollar question: does it work? In short, the answer is yes. Using it portable and running 20w, working Europe is not a problem and I suppose that with time I will manage to work farther afield. Using it mobile, I have made comparative tests with my helical whips, and although the test conditions were far from ideal, it seems clear that the MFJ does indeed work better. I have worked lots of DX, putting strong signals into Europe, the US, and Africa, and also managing to work the rare DX that has been around in the last six weeks, such as TO4E, T32WW, and 4W2, to name the ones that come to mind.
Additional notes:
MFJ make 12’ telescopic whips which can also be used with these antennas.
The power rating is 200w PEP. I have run 500w PEP from my ameritron amplifier without any adverse effects. The whips are solid, the coil wire looks to be thick enough, and I can only assume the 200w rating is conservative just in case someone melts the coil while trying to tune.
Conclusion:
I was delighted when these antennas were first advertised by MFJ. They fill a gap in the market, offering an antenna that is both small and light for stowing either in the car, backpack, or suitcase, yet offering full size performance on at least two HF bands (depending on the whip and coil combination used) and acceptable performance on the rest. These antennas should appeal to those who travel frequently and require a set-up that is both simple, quick and effective. Mine will definitely be coming with me on my next trip to C6-land!
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