Yet another empty Altoids 'curiously strong mints' tin is due to be pressed into service tomorrow, this time to accommodate a 2W QRP power meter. Using the little 250uA movement I have, it should read from about 100mW up to 2W reasonably well.
Based on a simple design by AA5TB, Ive had to recalculate the series resistor value, which meant quite a lot of first principle maths. The end result of all the calculations was a resistor value of 53.7k. Not a preferred value in anyone's book! Rounding up to 54k, also not a preferred value, I saw that the nearest available resistors were quite a ways out. So, my design will have a pair in series, a 39k and a 15k. The trick now though will be finding some suitably power rated 200 ohm resistors to build the dummy load section.
For tonight, there's little I can do, apart from paint the Altoids tin ready. This is also having a nice shade of grey, but this time in Revell Enamel.
I'll also be adding a bypass switch to my digimodes interface. This is a simple beast, a pair of 1:1 600 ohm isolation transformers for the audio and an opto-isolator for the PTT control
It is however, very customised for my station. The socket on the front is for the Alinco DX-70's microphone, a DIN socket on the back then connects via a patch lead to the Alinco's microphone socket. This means I can select between mic and audio in/out lines, the front panel switch being for that purpose. The PTT control is via RS232, but this is also fed out the back via a 3.5mm stereo jack to the CAT interface for my FRG-100 receiver, allowing computer control of that as well. The bypass switch I wil fit tomorrow will allow switching out the level control pot.
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