[Elecraft] K3 and Alpha 91b

Wed Jan 20 11:33:12 EST 2010

Hi Brian,

Thanks for the feedback ... 

I've had no issues with the 91b except for this oddity since I 
acquired it about three weeks ago.  I previoulsy owned a 91b and an 
87a but ended up selling the 91b to a friend along with a Collins S 
Line.  I sold the 87a (HUGE mistake) and bought a Quadra when I 
slimmed down my radio "collection" to a Yaesu FT-1000MP MK V and a 
portable FT450 a couple of years ago.  I sold the FT-1000 last 
December and bought the K3.  After I assembled it and got it on the 
air, the Quadra became a bit of a pain to deal with because of the 
way it senses RF to switch bands (No Data Cables to run between K3 
and the Amp) and the extra buttons that had to be pushed on the amp 
to switch the bands and tune the amp.  So I traded it to a friend for 
his
91b.  Not sorry I did that at all but this oddity with 80 meter SSB 
is
bothering me.  I am running 30 watts and getting the 1500 out but I 
should
not have to when all other bands, including 160, take 45 watts to 
achieve
1500 out into a matched antenna or a dummy load.  

As to RFI issues, I have a pretty good ground system ... copper water
pipes and a city water system that is copper all the way to the 
street 300
feet away.  With in-line traps between the radio and amp and between 
the
tuner and the antenna the only issue I have is on 10 meters when I do 
get
into the TV and Phone if I run anything over 600 watts ... I think 
it's
more antenna proximity that RFI but I'm still working on that.

I use filters on all the phones ... you might try that.  Before 
Verizon switched me to fibre optic cable I was on a residential DSL 
line and I was forced to use band pass filters on all the phones in 
the house to keep 80, 10 and 15 meters out of the system at any power
setting over 500 watts.  I did discover a ground cable issue when I 
was
moving the station around after getting the K3 that may have 
contributed
to that however.  I run all grounds to a single point with all 
radios,
computers, amplifiers and accessory equipment having separate ground
cables to that point.  Loose connections and AC wiring without chokes
still pop up as issues occasionally due to my missing something.

73, Mike N9QR

Date sent:      	Wed, 20 Jan 2010 10:06:08 -0500
From:           	Brian Machesney <nekvtster at gmail.com>
To:             	Elecraft Reflector <elecraft at mailman.qth.net>
Subject:        	Re: [Elecraft] K3 and Alpha 91b

> Mike,
> 
> I have used my K3 and A91b successfully on all bands from 160
> through 10
> meters for over a year. No problems with SSB on any bands. I have
> run full
> output on 160 and 80/75, both SSB and CW. Net: I can't think why
> you're
> having trouble.
> 
> I do have one problem on the low bands that I do not associate with
> the K3
> but might be playing into your situation somehow. I believe my house
> wiring
> is picking up RF, which kills my DSL connection whenever I run high
> power on
> 160 and sometimes when I only run 100W barefoot from the K3.
> 
> Have you run the setup into a dummy load?
> 
> Brian K1LI
> 
> On Tue, Jan 19, 2010 at 3:59 PM, <n9qr at aol.com> wrote:
> 
> > I have an Alpha 91b hooked to the K3 (SN 8376) and I'm having an
> "Odd"
> > problem ... on 75/80 meter SSB, if I run the amp at 45 watts,
> which is what
> > works on CW without issue, I encounter significant nuisance
> tripping of the
> > Amplifier to the fault condition.  The amp also exhibits a power
> spike into
> > the 2KW range often times when it faults.  If I reduce the  power
> to 30
> > watts on the K3, the amp runs 1500 watts OK without tripping.  
> Please ....
> > resist the temptation to say "Run at 30 watts then".  All  other
> bands ...
> > except 6 meters which I didn't check, do not exhibit this  issue. 
> Power
> > out from
> > the K3 is 45 watts and the amp runs  1500 watts  out with NO
> nuisance
> > tripping.  I've talked to the tech's at Alpha and at  least one
> other K3
> > owner
> > has had this same problem.  He asked me to check  the amp with
> another
> > radio
> > so, using my spare radio, Yaesu FT-450, to drive  the amp I have
> no
> > nuisance
> > tripping on any band while running 45-50 watts into  the amp. 
> Neither
> > radio
> > has ALC hooked up, only the TR relay.  Both  radios and amp are
> grounded to
> > the same ground buss.  RF calibration was  done when the radio
> was
> > assembled and I have not re-done that process.
> >
> > Any ideas as to why the radio would exhibit a tendency to over
> drive the
> > amp just on 75/80 meters?
> >
> > Mike N9QR
> >
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