HF MOBILE CW even QRP by Petr, OK1RP


Inspired by Mark W4CK, Chris K4EFZ and Del W8KJP I am sending also some experiences with HF Mobile CW operation.

Since May 2002 when I bought my new toy MX-21S CW/SSB 2W QRP tcvr from Mizuho I have been experimenting with HF CW from my car even QRP power. I am living in Kostice, small village about 45 miles away from Praha where I am working in MIRACLE Network Ltd. as an Export Sales Mgr. of the micorwave links. Cause I am driving daily two times this distance so I am spending each day aproximately 2hrs on the way in the car. As Mark, W4CK said I now spending rather productively on the bands!

The rig I use is a Mizuho MX-21S tcvr for 15m CW/SSB with 2W output max. where builded inside VXO, RIT, ATT, 4 crystals IF filter all in handy size including the battery if need it. There is no problem to charging batts with the circuits inside also. I am using the DC-DC adapter connected to the main battery in the car and fused of course.

The second rig I use is an amazing SW-20 from Small Wonder Labs by Dave, K1SWL. This famous rig I builded from original company kit. Works as the monoband superheterodyne on 20m, 3 crystals on 9MHz IF, uses NE602 IC on mixer stage with tuned bandpass front-end. Power I have adjusted to 1W output only cause of battery consumption when I am using it for backpacking, but PA is able to manage 3W out. ( many thanks for all modifications emailed by Fraser, G4BJM! )

The antennas are simply home made vertical mobile whipes mounted on magnetic base in centre of the roof. Mainly I am using aprox. 1.5 to 1.8m long whipes originaly used for CB and matched inside the car by manual tuner and SWR meter checked. Well I know that it is not electricaly ideal solution, but I am not able to put any fixed configuration with regular matching cause of the company car and rented only. Many times I tried to use the telescopic whipe originaly made by Mizuho where 1.5m radiator is matched by coil in base. There was not big differencies between these configurations in my case.

I was really amazed how works both radios even with really simple antennas when I tested it on hills or mountains. Mainly the reception was so clear and easy that I did not know from the big industrialised cities. Over the following months I tried many different mobile configurations of the two radios and whipes antennas with varying degrees of success. Well main problem was too small power which not exceeded 1.5W output all the time. Also I had not any suitable paddle ready to use at this time so I used old army pump key during my mobile CW operations. In general I had to say that HF Mobile CW is usable even the QRP power only, but You have to be prepared that lots operators will not have patience with Your really weak signals and that this temporary set-up is not suitable for long rag-chewings so much.

As of the middle of Nov 2003 I have logged many QSOs since Spring 2002. Also some CW clubs QSOs made on 15/20m. Now I am preparing a bit more power for serious mobile operation mainly when conditions will be so poor like a few week ago. Mobile CW even QRP is wonderful for longer trips as Del, W8KJP/m said…You can be with Your best friends by means of radio and You will spend this time much better and productively than phones talking stuff and nonsense…

73 de Petr, OK1RP/m

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