[Amps] HV MOSFETs for RF

[Tom Thompson]

I show how to construct a simple 40-dB, RF SAmpler that will easily 
handle 1500 watts.  It is printed in the ARRL handbook under 
Construction Projects in the Test Equipment and Measurements section.

Tom   W0IVJ

On 5/12/2017 11:39 AM, Doug Ronald wrote:
> 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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