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+--- Thread: 23cm amp development at W6PQL (/thread-478.html)
23cm amp development at W6PQL - ZL3RC - 03-01-2018
Was having a look at Jims web site to order some more bits and noticed some interesting text at the top of his home page.
"Coming in late January, a single-device 650w amplifier for 23cm (50V LDMOS). (see the initial documentation here)"
Have a look and see whats on offer. Ive been waiting for something like this to turn up somewhere after that Freescale amp article in Dubus a while back.
If you look at the possible device cost and the basic kit cost its not too bad and Im guessing its going to make a huge impact to 23cm EME.
Lets hope this one actually turns out to be the "real thing" not like some of the others.
Cheers
Roger ZL3RC.
RE: 23cm amp development at W6PQL - VK2ZIW - 14-02-2018
Hi all,
On hols, Diamond Head NSW.
At $12 ea. I bought six MRFE6S9160 LDMOS transistors six months back.
I found plenty of designs for these.
I got the heat spreader from my local metal scrappie (Penrith NSW) two pieces
of 4" copper bus bar 1/4" thick. I was stoked, $40 for six spreaders.
On looking at the designs, I see no reason for PCB. Surely, copper strip laid over
teflon sheet and clamped in place will work.
I'll be able easily to get the stripline impedance down to 5 ohms, then a Pi coupler.
150W per transistor, two will get close to our legal limit.
Power supply: my 24V UPS battery system, now solar charged.
Alan VK2ZIW
RE: 23cm amp development at W6PQL - VK3WRE - 14-02-2018
(14-02-2018, 05:27 AM)VK2ZIW Wrote: Hi all,
On hols, Diamond Head NSW.
At $12 ea. I bought six MRFE6S9160 LDMOS transistors six months back.
I found plenty of designs for these.
I got the heat spreader from my local metal scrappie (Penrith NSW) two pieces
of 4" copper bus bar 1/4" thick. I was stoked, $40 for six spreaders.
On looking at the designs, I see no reason for PCB. Surely, copper strip laid over
teflon sheet and clamped in place will work.
I'll be able easily to get the stripline impedance down to 5 ohms, then a Pi coupler.
150W per transistor, two will get close to our legal limit.
Power supply: my 24V UPS battery system, now solar charged.
Alan VK2ZIW
Hi Alan, last year I built a few amps using the MRFE6S9160 devices. I used a variation of a European design on Rogers 4003 board and have had
good success with it. 140 to 150 watts out with 1.5 watts of drive at 28 volts, they do like the volts !. I also have a pair coupled together that produces
290 watts and at that level the inter connect coax gets a bit warm. so all in all a good reproducible project.
https://vhfdesign.com/wp-content/uploads/2016/12/PA-23cm-150W-PCB-768x353.png.
I changed the bias arrangement on my design.
Ralph VK3WRE