[Amps] RF2K+ LDMOS linear

Jim Brown jim at audiosystemsgroup.com
Sun Jun 4 12:54:22 EDT 2017


N2IC and W8HW have made compelling arguments for not viewing this new 
amp as a panacea, and in pointing out shortcomings that have long been 
well known.  I currently own three Ten Tec 425s, two 87As, a KPA500, and 
a Ten Tec Herc II. The 87As are newly acquired, the Ten Tecs have gone 
into the back room. They served me well, and all three work fine, except 
that the power transformer is fried in one of them. The KPA500 gives me 
550W on 6M, and is instant on, so it's my non-contesting amp. And I keep 
that Herc II because it runs on 12-14VDC.

I would strongly encourage the guys in Germany producing this amp to get 
a couple of them into major contesting stations so that they are 
subjected to the sort of mistreatment that can result from contesting. 
There are certainly good ones in Germany, and Steve's (N2IC) station 
would be a great test bed here in the US.

Another possible RF noise issue is from the PWM control for the fan. 
Such systems are notorious for RF noise. There are, of course, good 
solutions, but they must be applied at the design stage.

I'd also like to hear about antenna switching and QSK.

73, Jim K9YC

On Sun,6/4/2017 6:58 AM, Steve London wrote:
> I would not declare tube amplifiers dead until a legal limit, SS 
> amplifier repeatedly proves itself in serious contest conditions. I'm 
> not talking about the guy who casually makes 500 search-and-pounce 
> QSO's. I'm talking about the balls-to-the-walls, SO2R, all-band 
> guy/gal who operates close to 48 hours, running stations the entire 
> time. Mistakes happen under these conditions - ooops, forgot to change 
> the tornado tuner on the 80 when moving from 3700 to 3800, etc. Or, RF 
> from one amp gets into the other amp and fools it's microprocessor.
>
> The only production SS amp that has come close to proving itself under 
> there conditions is the SPE line. Even they aren't perfect. See 
> http://www.3830scores.com/showrumor.php?arg=leadzTgmmcvix . That was 
> an SPE 2K. In all fairness to SPE, see 
> http://www.3830scores.com/showrumor.php?arg=lua4zPgqvqmsK . A pair of 
> SPE 1.3K's that worked flawlessly. (However, not at the legal limit.)
>
> I would love to borrow a pair of these RF-Kit amps and put them to 
> serious use in one of my SO2R contest efforts.
>
> 73,
> Steve, N2IC
>
>
> On 06/04/2017 07:01 AM, Jim Thomson wrote:
>> Date: Fri, 2 Jun 2017 19:59:34 -0700
>> From: Mark Mumaw <nu6x at esedona.net>
>> To: amps at contesting.com
>> Subject: [Amps] RF2K+ LDMOS linear
>>
>> <I would like to clear up the information on the RF2K+ by RF-Kit.de in
>> Germany.
>>
>> I have tried to join the list but have not been able to get 
>> confirmation.
>>
>> If this message goes through I will followup with another message
>> answering  the questions I have seen here.
>>
>> BTW, I am not an Agent or Employee of RF-kit.de. I have built several of
>> these linears and I have volunteered to help with the English version of
>> the Manual.
>>
>> Mark NU6X  Sedona, AZ
>>
>> ##  At  $2685.00  to  $2985.00   +  another $270.00  for shipping + 
>> misc parts  =  $3255.00
>> for the amp + tuner, + shipping, raspberry pi3  for the full blown 
>> version.
>>
>> ##  At that price point, this now spells the end of the tube era.   
>> Done, finished.  End of story.
>> SS   160-6m Auto tune amp, auto tuner, no expensive tubes to buy, 
>> super light weight etc.
>>
>> ##  No auto tune tube amp covers HF + 6m.   To get  HF  + 6m from say 
>> Alpha, with 2 of their alpha amps,
>> you could  buy 4 of these  SS amps, and have $ left over.
>>
>> ##  The ameritron AL-1500   lists for  $4295.00  + shipping...doesnt 
>> have 6M, no auto tune, no auto tuner...so its toast.
>>
>> ##  alpha  9500  lists  for  $7995.00  + shipping.  No 6m.  No auto 
>> tuner.   Its now toast.
>>
>> ##  alpha  8406 manual tune 6M amp.  $4995.00  + shipping. Toast.
>>
>> ##  all these current tube amps are now kaputsky.    Emtron is 
>> already doa.  Eimac has priced themselves into oblivion.
>> If the chinese stop making tubes, your tube amp will become a door 
>> stop.   Get rid of it while you still can.   Hats off to the
>> german folks who have now put the final nail in the coffin of the 
>> tube era.
>>
>>
>> Jim   VE7RF
>>
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