Thursday, October 4, 2012

RockMite 30 Update

Well some good news, I’ve had my first QSO with the RM30 but there have been some minor issues along the way.  
After completing the build and doing some further testing  it became obvious that the transmit was not working as it should, I was using the 2N3053 transistor with the 2 ohm resistor in R18 and of course the bifilar toroid filter mod in L1, but I was only getting about 400Mw out when I should have been getting around 700Mw.
On further investigation/checking and through chatting on the Yahoo Rock-mite forum it eventually came apparent that I was using the wrong toroid FT37-6 as opposed to T37-43.
 Unfortunately I did not have that particular toroid so after having a good think realised the best way forward was to revert back to legacy and remove the T37-6 and pop L1 back in and use some jumps to bypass the trace cuttings.
Actually surprisingly enough it did not prove too difficult and I soon had the RM back up and running pushing out approximately 600Mw of juice.
At the same time I had a play with various transistors I have, the standard 2N2222 and the 2N3053 plus another, the 2SC799 which in theory can give you up to 2 watts of power. Sadly with my RM30 it hardly gave me any power, so either it’s broken or my set up is incorrect for that transistor.
So I reverted back to the 2N2222 and after a couple of attempts Calling CQ this morning I got DL6FAX, Konrad in Korbach a distance of 670 miles , not bad for my first attempt and Konrad was kind enough to give me a 569!
I’ve now ordered the correct toroid which should arrive later this week and then I will do some further experiments and we’ll see how we go from there.
The main thing is all my RM’s are now built and thankfully working correctly, something I would not have dreamed of if you had told me at the beginning of the year. 

Some further news regarding batteries, at present I have been using standard 9v batteries, which are fine but obviously not rechargeable. A member of the Yahoo RockMite forum announced last week that he had purchased a re-chargeable 12v battery from China which by all accounts seemed to fit the bill for RockMites really well.

So I took the risk and also bought one, it arrived the other day and I’m really pleased with it. It comes complete with charger and 3 pin plug (for UK users) and seems to hold the charge pretty well. It’s excellent for when I want to get out and about, not bad for £8.00!

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