The 6M-160M HPSDR Transceiver Project Begins

[K1JJ]

Frank,

Here's an intersting statement by the same German ham who is seeing -50db 3rd with the 400w dissipation bi-polar amp.  He feels the IMD improves with less power with his bi-polars.


I sent you the pictures and spectrum results of his tests.

T
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 "I've never seen better IMD results in amateur equipment, didn't expect it with this kit.
The MosFet amplifiers they are building with the new Mitsubishi transistors are not bad, however, only at full output power. I was very much disappointed with my FLEX in this respect, since IMD3 is rather poor reducing the output power to less than about 30W. That's not the case wih this bipolar amplifier chain. IMD continuously improves when reducing the power."

[WA1GFZ]

I saw the pictures. Interesting. That may be the same board as the bipolar amps we built years ago but the output transformer is a lot better. FETs by nature have better higher order IMD though. Gee I have a pile of MRF429s and a MRF433 driver amp in a collins module.
Still, I'm sticking with FETs. I get back to that at some point. Last night a 4X4 friend sent me an article on a FET amp that does -40 dBc IMD3 at 400 watts out. Big FETs though.

BTW METIS is up and running. Just came upstairs to download the programmer software to update Mercury and Penny firmware.
Hope to be on the air soon.

[K1JJ]

I wonder if the Metis reduced your CPU % usage?  It seems most of the guys are seeing it.

Yeah, it's about time the HPSDR guys focused on a reliable, repeatable, 100w amp that has super clean output like Penny or Hermes.  Right now everyone settles for less or gropes around looking for something.  Use a big heatsink with water cooled options and let the guys set the idle and power output wherever they need to achieve their goals.

T

[WA1GFZ]

CPU down to around 10% from 16% with the USB interface
Audio settings seem tamer with the new power SDR.

[WA1GFZ]

HPSDR upgraded with all new firmware / P SDR. Works great.