Posts by SP8NAJ

  • What TX amplifier do you plan to use?

    Alex, please verify bias voltage. My first test with lab PA and 24V, on the right transistor was close to 3A, but for short time and I never see it any more. On left 20mA and similair situation. Now I added external bias voltage and all is ok.


    73 Henryk

  • What TX amplifier do you plan to use?

    Hi colleagues,


    Thank you very much for nice job in here. I baught also one PA from Poland. Base on your test I have turnd on my board... not so bad, but... look on the picture below:


    Due to this: .



    I did like this:


    And how it look at the oustide:


    Dismantled cirulator place is perfect to install N socket. Two holes exeactly on correct position, for another two you have to modify holes on the socket - Dremel machine is the best. Now I have typical N socket, much better than this oryginal non typical one. On the cover you have to drill 20mm hole with 25mm distance on stright line from screw - very easy to do it.

    What hapened with trace? Who knows in details, but in one moment I saw 15A from 27V PS and next some sparks, that's it. Maybe my modification of outlet socket was not proper. Now is haevy duty :).

    For now only circulator was remowed, installed combiner (bigger) and bias setting as recomended. The rest oryginal without any snowflacking up to now. I use Dx Patrol - only 100mW output. Due to this is better to use preamp also. On the inlet is 3dB att, i have added SMA att 2+5+6 dB for tests. Step by step I have removed one by one... current increased and finaly without external att I have whistled harder to the microfone.. and you see efect. But as DB8TF wrote: they are really solid and all transistors survived. Now during test "only" less than 10A.

    Unfortunately I havent now any measurement equipment for 2,4 and I use only DC measurement with Dummy load. With 12m of RF7 and 8m of H155 I saw my signal on sattelite a bit lower than CW beacon. I know, that cables are not for this aplication, but I used what I have connected to my shack. First test done.

    I don't need high power, but PA will not be very close to the antena, than I need few wats more to cover losess on the cable and additionalk few wats because I plan to use smal wi-fi grid antena.


    73 Henryk