A while ago I bought a digital fieldstrength meter kit from QRPguys. I have made myself a very nice analog fieldstrength meter in 2014 which does a nice job but is not much more as a indicator. I hoped the digital one would be more precise.So, a few weeks ago I started to build the kit. So far, no problem. All components were there and the instructions are very clear to me. Till I came at the digital voltmeter part...
The voltmeter needs to be modified to read the low voltage output of the LM358 op amp. This is done by bypassing the input scaling resistors.
However, none of the pictures in the instruction does match the voltmeter supllied with the kit.
So, I wrote QRPguys and within a week I was answered with another drawing of a different voltmeter and how to modify it. Unfortunately this drawing still didn't match the voltmeter. So I wrote QRPguys again 2 weeks ago to ask them for a solution. Unfortunately till now I didn't get any answer, they probabely don't know a solution I guess.
I think this shouldn't be a difficult mod but I'm not that smart I can instantly see what to do. Without the voltmeter the whole kit is useless. I hope one of my readers can tell me how to modify it.
Here is the picture I also send to QRPguys to examine.
The original building instruction can be found here:
https://qrpguys.com/wp-content/uploads/2019/05/fsm_assy_050219.pdf
No comments:
Post a Comment