[Amps] Future of RF AMPS

[dsolberg at wi.rr.com]

Helge Granberg (SK) wrote a Motorola engineering bulletin many years ago, EB104, that used (4) MRF 150's for 600 watts.  The circuit board for this is available from CCI, and many hams, myself included, have built this amplifier.  The circuit design is good but the printed circuit board leaves a lot to be desired.  Several commercial amplifiers have evolved from this design including Ameritron and Tokyo Hy Power.  Tokyo Hy Power replaced the MRF150's with SD2933's.  UA3QLC, and other hams in Russia, have also taken the EB104 PCB and enlarged the MOSFET openings for SD2933's.  They are getting 1KW with this change.

Ken Holland, K9FV, and I (K9AQ) have designed a new printed circuit as an alternative to EB104.  This PCB is made for the SD2933's. This design incorporates a lot of the modifications that hams have done over the years to EB104, as well as using a transmission line transformer for the output.

I have completed bench testing of the new amp and I am in the process of putting it in the cabinet that previously was used with my EB104 board.

After we get a few more of these built and tested by some other hams, we will make this PCB available at cost, which is around $40.

This is NOT a project for an inexperienced SS amp builder!  Used SD2933's are available once in awhile at low cost, others wise they are about $100 a piece, so making a mistake can be costly.  While the amp is working quite well with around 1KW output, I am sure there are some minor circuit tweaks that still could be done.

I have written an article on improving the EB104 design with a transmission line transformer, but it has not been published.  I will be glad to share it, if you drop me an email.  My email is correct on QRZ.

73,

Don
K9AQ

I will also be writing an article on the new SD2933 amp when I find some time.


---- Leigh Turner <invertech at frontierisp.net.au> wrote: 
> 
> Dick, such reproducible cookbook reference designs will inevitably appear in
> the ARRL Handbook or a QEX article one day; already a capable 250 Watt SS
> amp with decent specs was published in a recent edition.  There's certainly
> a lot of isolated ham shack experimenting with bespoke solid-state seriously
> QRO HF amps going on and someone coming out and publishing a general design
> and construction article would surely be imminent. 
> 
> 73
> 
> Leigh
> VK5KLT
> 
> ________________________________________
> From: Richard Solomon [mailto:dickw1ksz at gmail.com] 
> Sent: Wednesday, 11 September 2013 10:32 AM
> To: Leigh Turner
> Subject: Re: [Amps] Future of RF AMPS
> 
> I haven't seen anything in print that would let me build something like
> that. While I have built some tube amps and converted some to 6 Meters, I 
> don't consider myself an RF Design Engineer, so I would need something 
> to go by.  I have no qualms about taking a crack at building one, but I
> hesitate to embark on a "blank sheet" design.
> 
> 73, Dick, W1KSZ
> 
> On Tue, Sep 10, 2013 at 5:51 PM, Leigh Turner <invertech at frontierisp.net.au>
> wrote:
> 
> Dick, there's no need to wait for such innovations in RF power
> semiconductors as such a long awaited low cost S.S. 1.5 kW HF amp can be
> economically homebrewed using a readily available multiplicity (6 devices in
> parallel/push-pull) of cheap 50V RF MOSFETS sourced from the surplus market.
> The overall BOM will not break the bank, and such a rewarding project is
> well within the scope of the tech-savvy ham experimenter (that rarefied
> breed that remains amongst us in 2013, as distinct from the ubiquitous
> appliance operators).
> 
> Leigh
> 
> VK5KLT
> 
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Richard Solomon
> Sent: Wednesday, 11 September 2013 9:59 AM
> To: amps at contesting.com
> Subject: Re: [Amps] Future of RF AMPS
> 
> I doubt I'll see this filter down to Ham Amps in my lifetime. I'm still
> waiting for a decent SS Amp that runs 1.5 KW out and does not cost a
> fortune.
> 
> 73, Dick, W1KSZ
> 
> 
> On Tue, Sep 10, 2013 at 10:03 AM, <donroden at hiwaay.net> wrote:
> 
> > Gold-Clamp Transistors
> 
> ++SNIP++
> 
> 
> 
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