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Re: [Amps] Future of RF AMPS

To: amps@contesting.com
Subject: Re: [Amps] Future of RF AMPS
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Wed, 11 Sep 2013 16:05:50 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>

None of the Communications Concepts two amplifier combiners are rated
at 2 KW.  They show 4 amplifier (4 port) devices for 2 and 5 KW but
the only high power 2 port combiner is rated for only 1 KW.

While it might be possible to modify one of the 4 port sets for 2 port
operation, there are no application notes on the site concerning the
splitter/combiner products.

73,

   ... Joe, W4TV


On 9/11/2013 3:45 PM, dsolberg@wi.rr.com wrote:
Richard,

Communication Concepts sells combiners that should work. 
http://www.communication-concepts.com/index.php/splitter-combiners.html

Don
K9AQ
---- Richard Solomon <dickw1ksz@gmail.com> wrote:
Rumor has it that RF Parts offered a High Power Combiner, but a search of
that site
does not show it. There are a few Combiners, but no Data to tell what they
do.

Anyone have a source for a Combiner that will handle 2X 600 to 800 Watts in
??

73, Dick, W1KSZ


On Wed, Sep 11, 2013 at 9:41 AM, <dsolberg@wi.rr.com> wrote:

While the MOSFETs can output 1200 watts with four in parallel/push-pull,
the output transformer ratio will limit the practical output to between 800
and 1KW, using a 9:1 with a 50V power supply.  The 9:1 optimal output is at
800 watts.  Tokyo HyPower uses this design and they rate it for 1KW.  I can
also get 1KW with my homebrew amp with (4) SD2933's, but prefer to run it
closer to 800 watts to improve the IMD.

If you really want the full legal limit, you would be better to have two
PA modules and a combiner.  Otherwise the output transformer design is
going to get real complicated.  The other option is running higher voltage,
which complicates the selection of a power supply.  50 volt computer server
switching power supplies are low cost and easy to obtain.

I am happy with 800-1KW, but maybe someday I will try the combiner just
for the fun of it.

Don
K9AQ
---- Leigh Turner <invertech@frontierisp.net.au> wrote:

Larry, the RF power MOSFETS to which I refer here are the VRF2933 devices
from Microsemi. Sometimes one can find surplus and NOS ST Micro SD2933
FETS
on eBay at low prices.

4 of these rugged 300 Watt rated devices in parallel/push-pull will
yield a
saturated output power of well over 1200 Watts.  Six will comfortably
yield
over the US legal limit.

73

Leigh
VK5KLT

-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Larry
Sent: Wednesday, 11 September 2013 10:48 AM
To: amps@contesting.com
Subject: Re: [Amps] Future of RF AMPS

On 10-Sep-13 5:51 PM, Leigh Turner wrote: using a readily available
multiplicity (6 devices in parallel/push-pull) of cheap 50V MOSFETS
sourced
from the surplus market.


Leigh,

Exactly which cheap MOSFETS from what surplus market are you speaking of?

Larry - W7IUV

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