Hi,
I have not checked the topology chosen by Hans for the PA and this is just for comparison.
With the KD1JV ATS/MTR series of transceivers, we achieved 5W from 3 Bs170 at 12V on 20 meters CW.
Power drops to around 3W at 9V.
They are happy at 12V not getting hot if run to a 50 ohm load.
However the are getting touchy if the impedance goes too low and keeping them at 10V makes the PA sturdier.
The highest frequency achieved with the ATS/MTR is 15 meters, but I am not sure this limit comes from a restriction in the PA. Overall this is more a design choice and the main limit being the power consumption of the DDS in receive mode. These are rigs to bring in SOTA expedition and must be small and use as little as possible power from batteries.
I repeat this if is for CW and I guess for continuous transmission I would not go above 1W.
Last thing, the ATS/MTR series use a MSP430 micro-controller. I have started to modify KD1JV code to turn the MTR into a QRSS beacon. However it is such a good transceiver and buying one is so hard that I finally built my own QRSS/WSPR DDS beacon design...
73,
Yan.
---
Yannick DEVOS - XV4Y
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--- In QRPLabs@..., "andyfoad@..." <andyfoad@...> wrote:
Has anyone tried running 3 x BS170's at 12v yet AND measured the
output at 28Mhz please ?
(Please note, if you have nit used 28Mhz yet then you might need
to tweek the blue DDS pot to get it started.)
I run a full house of BS170's at 9v @ 28MHZ and get 260mw.
73 de Andy G0FTD
