Month: August 2012

QRO Portable Operating

Last night decided to dip my toe into the world of QRO portable. With the assistance of John M0UKD. To qualify for QRO in the UK you need close on 400w, yes I know this is QRP in the USA ! ….or Italy…

Equipment used:
Icom 7000 Linear Amp Explorer 1200
12m roach pole Linear Amp SPC tuner
Doublet antenna
(20m per leg)
Honda EU20 generator
(LPG powered)
65Ah battery to power the radio.

As I had never ran QRO outside before, the afternoon / evening was very much an experiment. I looked to answer the following questions.

Would the generator cope with the changeable SSB current load characteristics?
Would the RF be too much for the Icom (and maybe operator)?
Would my speaker wire antenna cope with 400w?

The first issue was resolved very quickly, the generator would power up the amp heaters….well no heaters no amp so that was a good start.
The Honda has two basic setting for power delivery, low demand or changeable high / low demand.

I set the generator to low / high and we started at a modest 100w (RTTY setting so 100% duty cycle) out of the amp, no issues. We then quickly progressed to 200, 300 and 400w again no real issues. I of course didnt pass the 400w setting, as this would clearly be in breach of my licence and I didnt have my 50 Ohm load to hand.

It would seem the generator did take a few seconds to recover, but this was going from little or no load to pulling some reasonable current. The power would jump up to 300, then as the generator recovered it would climb to 400w quickly.

The next test was the amount of RF flying around, John UKD had a basic RF field strength meter and while this was not designed to provide absolute measurements it was a relative indication. This indicated the RF close to the operating position was nothing above the usual levels, the antenna center was 12m above our heads…

A walk around indicated lots of RF was radiating from the antenna so it was all systems go, or should that be CQ.

80m was the band of choice, as 40m was quite poor with little UK activity. We quickly built up quite a few calls, and one thing became evident quickly…our signal was quite big! Typically we was 10dB up on your standard 100w station, and 20dB up on most M3 /M6 station. If you couple this with the fact that we had an antenna that was reasonably efficient it did provide some interesting operating.

On some occasions we were being called by stations we simply couldnt pull from the noise, as many stations (me included from home) simply cant radiate a good signal on 80m due to the low ERP or ability of my antenna to convert W to RF.

We worked 50 station in total, including Peter G3ZRS who previously was  Linear Amp UK. He commented that “your using an amplifier that I built”

Pictures of the equipment can be found online here.

73 Dave M0TAZ.

© 2015 Dave, M0TAZ