Re: 70 Watt amplifier kit for 23cms coming soon

Chris G0WUS

Hi James put me on the list for a kit please

73 chris G0WUS

Sent from my Samsung Galaxy smartphone.

-------- Original message --------
From: Bob G8HGN <g8hgn73@...>
Date: 30/06/2020 7:01 pm (GMT+00:00)
Subject: Re: [UKMicrowaves] 70 Watt amplifier kit for 23cms coming soon

Hi James,

Could you put me on the list please, thanks,


On 28/06/2020 21:59, James Smith via wrote:
I found a source of power transistors and decided to try them using John G4BAO's PCB design which is now public domain. He has unfortunately , run out of boards so I made my own with a scalpel to a similar design to test these transistors. results are very good on the first try - 80 watts saturated 70 watts P!dB and a gain of 14.4dB , 28 volt supply at about 5 amps @ 70W.
I am now building another one to test repeatability and if all is good then I will order some boards and look to selling a partial kit of PCB, transistor and ATC caps. No Idea of price yet. 
Since the supply of reliable MRF286's has dried up , this may help as a stopgap until another design comes along.
With great thanks to John Worsnop G4BAO for having done all the hard work in designing the matching and the rest of the PCB.
I won't say yet what device but will let you know soon.
The device used is a MRF5S9070 and I bought them as new old stock NOS from a UK firm who had them in stock for many years
I will make them available in partial kit form with a PCB made with Rogers 4350 , power transistor and ATC and C0G capacitors and when all the development is finished I will write an article for here and for CQ-TV magazine.
The expected kit price will be £30.00 + postage
See G4BAO amplifier in photos
Email me if you are interested and I will put you on the list.

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