?

Hans

Thanks for your comments. The beacon has been running for several days now and the final seems ok temp wise with the output at 5.08V. I used this table of RF volts into 50 ohms



to determine the approximate power output. I will have to find a real 50 or 51 ohm load resistor and measure it again.

One problem I am seeing is the keyer often 'locks' up after sending the call once or a few times. Once though it ran all nite and was still keying. I wonder if it is related to the supply ? I am using an old Heathkit Reg P/S IP-18 that seems stable and clean.

--- In QRPLabs@..., "hanssummers2000" wrote:
>
>
> Hi Paul
>
> Congrats on finishing the kit. Yes, the transistor can get a bit hot when tuned for maximum output and it is best to turn the trimmer pot a bit back towards the "cold" end (ground) to lower the output a bit and feel more comfortable.
>
> 5.08V p-p into 36 ohms is not 250mW according to my calcs, it's 90mW. I think you have missed a divide-by-2 somewhere.
>
> Another thing to bear in mind is that the output low pass filter is designed for 50 ohm termination, I'm not sure what would change if you use 36 ohms.
>
> 72/3 Hans G0UPL
>
>
> --- In QRPLabs@..., "PaulG" wrote:
> >
> > Got the kit running on the bench still on 12 wpm with 36 ohm dummy load I am getting 5.08V p to p output on the scope. This is somewhere around 250 mw and is set somewhat below max output as max output causes the transistor to run pretty warm. I also found out that you can reverse voltage the PIC enough to cause a 2nd degree burn on the finger and it still seems to be working. I am letting it run overnight or for a few days before I put the antenna on it. Before it started working I had a bad looking sine wave at very low level. Also the final was amplifying this spurious signal. After poking and prodding and reheating some connections it starting running properly.
> >
> > Pix of it on bench at
> >
>