[Amps] HV MOSFETs for RF

[Doug Ronald]

A "Tandem Match" coupler is easy and fun to build. The coupling factor is
based on a turns ratio with 30 to 40 dB typical. An advantage is that the
reflected power is also available. If you home make the coupler, you can put
any connectors you like on it.

Doug W6DSR

-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Ken K6MR
Sent: Friday, May 12, 2017 10:33 AM
To: Jim Thomson <jim.thom at telus.net>; amps at contesting.com
Subject: Re: [Amps] HV MOSFETs for RF

"whats needed now is to get current SS and tube amp manufactures to include
a sampled output.   "

The new Elecraft KPA-1500  has the sample output.

Ken K6MR

From: Jim Thomson<mailto:jim.thom at telus.net>
Sent: Friday, May 12, 2017 7:50 AM
To: amps at contesting.com<mailto:amps at contesting.com>
Subject: [Amps] HV MOSFETs for RF

Date: Thu, 11 May 2017 13:49:19 -0400
From: "Paul Christensen" <w9ac at arrl.net>
To: <amps at contesting.com>
Subject: Re: [Amps] HV MOSFETs for RF

>" ##  If you think the 100w  K3s  paltry  -23 dbc  IMD3 is something to
write
home about.... go for it.   Ditto with the 400w yaesu FT-9000MPs ?12 dbc
IMD3. "

<<<<For the last two weeks, I've been testing the new ANAN 8000DLE.
Worst-case IMD at 200W is -75 dBc and close to -80 dBc on some bands.  The
PSDR mRx result was cross-checked with an Agilent N1996A spectrum analyzer.
The combination <<<<of LDMOS, adaptive pre-distortion and a highly-isolated
RF sample path back to the receiver's sampling input all contribute to this
extraordinary level of transmitted IMD performance.

<<<<Paul, W9AC


##  superb xcvr, esp with phase noise through the floor,  plus other
features like a .1 PPM TCXO  etc.   Ok, per the ANAN forum folks, the 8000
had a 30 msec latency...which is now down to just 20 msecs.  How do you
monitor yourself on headphones,
when on ssb ?     I have found that anything much over 5-7 msecs sounds
horrid in the headphones. That would be a deal breaker for myself.  Plan B
would be to monitor the audio,  b4 it gets to the xcvr.    Will the 8000 do
essb ?   The 8000 needs an outboard box, with a VFO and other common stuff,
like the flex offers.

##  I see they used a pair of SMA  connectors on the xcvr for the..... pure
signal pre-distortion jacks.    If the xcvr is used stand alone, with no
amp, then a simple U cable is used between the pair of sma connectors.   One
sma is the sample from the 200w pa, the 2nd sma is the main input for the
pre-distortion scheme.   When a kw linear amp is used, the U link is
removed, and the sample comes from the  kw amp.   Apparently the sample cant
be more than 0 dbm, and no less than  - 24 dbm.   So you would require a big
pad on the output of the kw amp, for the sample.    Dunno what type of cable
is required for the sampling, back to the xcvr ?    Can you use a bnc, or
something else than a SMA...at the kw amp end ?

##  A VA2  fellow from quebec has one of the other ANAN xcvrs, with the
pre-distortion scheme.    His IMD3 on his pair of 3-500Zs, with
pre-distortion  improved to  -52 dbc.   He sampled the output of the 3-500Z
amp..pad, then back to the xcvr. Looks like the typ  linear amp can have its
IMD improved a bunch, like  10 - 18+ db.    A  10 to 18+ db improvement....
even on a marginal amp is a win - win.

##   -75  to -80dbc  IMD is not even in the same ball park  as everything
else on the market..and NO class A blast furnace required.    I see the new
Flex  1500W  SS amp has a sampled output..to be used with any xcvr that has
the pre-distortion scheme.. like the ANAN xcvrs.   The current Flex xcvrs
dont have the pre- distortion scheme...yet, but at least they can see the
writing on the wall, and provided a sampled output on their 1.5 kw ss amp.

##  whats needed now is to get current SS and tube amp manufactures to
include a sampled output.    Plan B is to just use a T connector on the back
of the amp, and tap off the T..into a pad, then into the xcvr.

Jim  VE7RF


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