[Elecraft] K2/100 Problem with Hi Reflected Power driving amp

[Doug Joyce]

John / Don:  I don't have a K2 (just got my new K3/10 operational
yesterday), but I wonder why you need a tuner between the K2/100 and the
tube amplifier.  Shouldn't the tuner be put in bypass mode or does the
amplifier not have a tuned input on the various ham bands?

73, Doug  VE3MV

----- Original Message ----- 
From: "Don Wilhelm" <w3fpr at embarqmail.com>
To: <johna at arnoldassoc.com>
Cc: <elecraft at mailman.qth.net>
Sent: Saturday, January 10, 2009 12:53 PM
Subject: Re: [Elecraft] K2/100 Problem with Hi Reflected Power driving amp


> John,
>
> Just how high is the reflected power (do a TUNE and it will be
> displayed).  The KPA100 throttles back power if the SWR is greater than
> 2.0-1.
>
> There are several possibilities, and only some have to do with the
> K2/100.  One is a bad coax, another is a PL-259 that is not properly
> tightened to the KPA100 (or anywhere else in the system).  What happens
> when you transmit into a dummy load?
>
> Your problem may be in the input of the amplifier and not the K2.  If
> the amplifier drive impedance changes when it sees RF, then it may not
> be usable without modification.  Is there any chance that the input
> circuit to the amp is not fully switched and the bias stable within the
> 15 ms. period after the K2 key is closed?
> Does the problem show up only on CW or do you get the same result when
> operating SSB with PTT?  If that is the problem, you will have to
> speed-up the relay in the amp (or replace it with a faster relay).
>
> If this is a recently constructed KPA100, I have a different set of
> questions?  Do you find the same result on all bands or only one or
> two?  Does the Hi Refl message appear when working the KPA100 into a
> dummy load?
>
> 73,
> Don W3FPR
>
> John wrote:
> > Hi all. I have a K2 with the KPA100 installed. I'm using the K2/100 to
drive
> > a tube amplifier through a tuner. The K2-100 keeps tripping off with the
> > HiRefl message showing not every time, but often enough that a QSO is
> > impossible. The K2/100 doesn't 'reset' (has no output) when rekeyed
unless I
> > rotate the power setting knob ever so slightly.
> >
> > What am I doing wrong? Any way to increase the delay before the High
> > Reflected power takes effect as I suspect it's transient? I also have
the
> > t-r rel
> >
> > Any assistance will be greatly appreciated.
> > 73, John  WA6YSY
> >
> >
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