[Elecraft] K3 power amp 2SC2782

[Roger]

Examples of "14V" radios using RD100HHF1 final transistors and delivering good & stable results:

ANAN 100,200 & 7000 series (w/o PureSignal)		(3rd order IMD -30 dBc  average (-36dB referred to one tone)); see AB4OJs test
Kenwood TS 890S					(3rd order IMD -32 dBc (-38 dB referred to one tone))

YAESU and ICOM are running the same transistors in some of their models. I am not promoting any brand but it is nothing "magic" or "bad" with MOSFETS being used at 14 V. Sure their advantage of having even better IMD characteristics at higher voltages cannot be used in a 14 V system.

Roger/DL5RBW

-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of ab2tc
Sent: Sunday, January 06, 2019 1:42 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 power amp 2SC2782

Hi Wes,

Agreed. In my view FETs are a mistake at the 14V level. The old K3 bipolar PA is much better (but still not good).

Knut - AB2TC



Wes Stewart-2 wrote
> I have not observed a low power issue in my K3. OTOH, in my experience 
> the K3S PA has been a huge disappointment. One reason for buying a K3S 
> was a hope that the TX IMD would be improved with FETs. This would no 
> doubt have been true if Elecraft designed the radio for 50 VDC.
> 
> Wes N7WS
> 
> On 1/5/2019 3:16 PM, K9MA wrote:
>> I've always felt that the KPA3 in my K3 was marginal. For example, 
>> I've never
> <snip>





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