Tag Archives: generator

2010 Spring VHF/UHF Field day on 7 bands

For this event I took my usual station on 50 to 1296 MHz, plus my transverter and gridpack for 2403 MHz, Ted VK1BL’s transverter and gridpack for 3400 and Dale VK1DSH’s 10 GHz station (IC202, transverter, dish and tripod).

Contacts were made on all these bands.

Performance of the station on 1296 MHz was not as good as in previous years.  This may be due to conditions, or to a problem with my antenna or my location on Mt Ginini.  It is becoming increasingly more difficult to find suitable places where even two required directions are not partly blocked by the trees on that mountain.

Some pictures are already on http://www.flickr.com/photos/exposite/sets and I’ll be putting some also onto the vk1da.net photo pages.

Spring field day a wipeout for me

After lugging all my equipment for 50, 144, 432, 1296, 2400 and 3400 MHz from the car to the north side of the summit at Mt Ginini, it still took several hours to get set up and operational. I finally got on the air on all bands at around 6pm, after making some earlier contacts on 1296, 2400 and 3400 with VK1BL and VK2AES.

Later I made contacts were made with VK1BL/p and VK2AES/p on all six bands (3400 only with VK1BL) but conditions and activity from further afield seemed quite poor with only weak signals from a small number of other portable stations.

I was running my station from a newly purchased inverter generator.  This was not a name brand but an import sold by a Victorian dealer, mostly marketed via Ebay.  I was pleased that its noise performance was much better than my previous generator.  However at about 9pm on Saturday night, within 20 minutes have having its fuel topped up, it slowly ran down and stopped.  All efforts to get it going again were unsuccessful.  I SMSd the other local field stations telling them I had a power problem.  The next morning I could only pack everything up and go home.

What happens to the generator has not been resolved yet.  My confidence in this particular unit is zero.  I have not been able to restart it, despite following the advice of the dealer and changing the fuel to premium unleaded.  I can believe it would run better, but I don’t see why it would simply fail to restart on ordinary unleaded.

I did examine the spark plug and found it was fouled considerably.  The recoil starter still reveals compression is good so I don’t think the rings have given up.  I suspect ignition circuit failure.

Fortunately others didn’t have this problem and went on to make more contacts.  The contacts with Doug 4OE did not work out too well, with Ted VK1BL making only marginal contacts on 144.  Contacts on higher bands were not possible.   Conditions were simply too poor.

Better luck next time.

Generator blues

My GMC 950w generator which has powered about 5 of the last few years’ VHF field days, refused to start last week when I set out to change its oil.

There have been a number of GMC branded generators on the Australian market.  GMC (Global Machinery Company) was based in China, or was it just an Australian importer of various GMC-branded items?

Mine is rated 950watts, which should really be called 950 VA (volt-amperes) and is powered by a small 4 stroke engine.  My experience of it is that it is a quiet and reliable engine, and the generator produces enough power for my modest VHF/UHF portable station, which requires power for an IC910H and a TS670S plus some minor items like a 40w light globe and a couple of antenna rotators.

My only problem with it was that it produced radio noise at a quite high level, sufficient to require a noise blanker to be run on 144 and be noticeable on 432 MHz.  On 50 MHz it was S9, at a distance of 25 metres between the generator and the 6 metre antenna, an omnidirectional vertical. I tried shielding the entire generator by wrapping it in chicken wire connected to the frame of the generator.  No improvement.

Several other radio amateurs have suggested the noise from the generator is transmitted along the 240V cable.  I haven’t yet proved where the noise is being radiated from.

Last week I put oil into a new Chinese built inverter generator and started it for the first time.  It ran fine and the voltage output displayed as 237 on a DVM.

I found a small engine mechanic willing to look at the GMC generator.  He said the magneto assembly was touching the shaft and preventing it from moving.  He has readjusted it so that it runs smoothly and at about the right RPM.  I have yet to try to calibrate the speed for 50 Hz output but I have a DVM that does frequency among other things, so I should be able to take a low voltage out of my scope soldering iron transformer and see what the frequency is.  For that matter I should check the inverter generator.