Australian made mrf300 x 4 amp board sold on EBay

Note , at 2 mins 44sec, where I say 20 mtrs , it’s actually 10 mtrs.
After the trouble with my boards,
I asked my friend Steve, to send me down his board ,
He brought his before I had completed my own amp.
After rigging it up, I found I could not connect the bias with out tripping the current protect board.
So I investigated the bias circuit and found for some reason the bias was set for 7.5 to 7.7 volts?
This was causing the amp to draw more current than the protect board would allow.
Why the hell was the bias set so high? Was this even tested before leaving the manufacturer?
Was the board deliberately set up to fail? No way did it run with such a high bias voltage .
Once sorted , reset the bias, all was fine.
Well except for the poor efficiency and low power out put!
All 4 device where check and no short source to gate or gate to drain.
So all should be well...
Like my boards, they just won’t make decent power on 40 or 20 mtrs
On 10 mtrs yes it gets close to the makers video on his you tube channel.
Now the Bird watt metre with the 1000 watt slug, indicates 100 watts from the ic7300
So the bird can’t be that far out in its readings.
I have now been told, multiple times from RF engineers, the design doesn’t look right,
Poor input design and way too much cooper in the Drain circuit and that the supply voltage
Is too far away from the drains.
If you look at NXP data sheet for the Mrf300, They claim 320 watts from each device at 13.9 MHz
And 280 watts at the 1 dB compression point and the board is biased !
Here on this board each device is lucky to be making 150 watts, that’s if it could get too 600 watts
On 40 mtrs . The missing power is due to the poor efficiency. It’s wasted as heat into the heat sink
Then your going to drop some power due to all the harmonics scrubbed off by the filter .
Have a look around on you tube, guys are building 2 x mrf300 boards and getting 600 watts , here on this board we have 4 x mrf 300
And struggling to make 600 on 40 mtrs .
I could not recommend these mrf300 amp boards, instead I say, go to Greece , Russia , the Uk fellow Razvan - Qrp Blog.
Or the USA.
Sadly I brought these boards direct and now I regret not buying from eBay, if I had, I would not be stuck with them now.
Steve and I are now waiting for our new boards to arrive , I will take NXP advice and combine two boards and from what I
See from Greece - dx world on you tube, I will easily get 1kw after the filters.
Stay tuned That video to follow soon