[Elecraft] K2 Transmitter Alignment

[Don Wilhelm]

Doug,

First, what is your power supply voltage?  Is it sagging during transmit?
An easy way to check is the tap the DISPLAY button and then enter tune - the
display will show you the voltage and current.  If the voltage is sagging
low, blame your power supply or the connecting cable.

If the voltage is good (12.5 to 13.8 volts) during transmit, then you do
have a problem with the transmit chain gain.  Check T1, T2, T3 and T4
carefully.  Make certain they are wound with the proper number of turns and
look like the diagrams in the manual.

If all is OK in the above checks, then the problem source will have to be
found the hard way.  The first step is to make up the RF Probe shown in
Appendix E of the K2 manual (parts are included with the kit).  If you have
a good 'scope, you can use that rather than the RF Probe.  What you will
need to do is go through the Transmit Signal Tracing procedure in the K2
manual Appendix E.  You will be looking for the stage where the RF voltage
becomes significantly less than the expected value listed.  If you need
assistance with this signal tracing procedure, just ask and we can provide
more details.

73,
Don W3FPR

> -----Original Message-----
> From: Doug Person [mailto:Doug at Northroutt.net]
> Sent: Tuesday, November 21, 2006 6:35 PM
> To: w3fpr at arrl.net
> Cc: Elecraft at mailman.qth.net
> Subject: Re: [Elecraft] K2 Transmitter Alignment
>
>
> Hi Don,
>
> I found the problem.  and you were right - it was the bandpass filter.
> I had C220 and C221 reversed.  After a bit of fooling around and
> realigning, 17 is OK.
>
> What I now have is generally low output.  About 9 watts 80 through 20, 6
> watts on 15 and only 3.5 on 12 and 10.
>
> Any thoughts?
>
> Thanks & 73,
>
> Doug -- K0DXV
>
> Don Wilhelm wrote:
> > Doug,
> >
> > The only thing unique to 17 meters is the 15/17 m bandpass
> filter and the
> > 17/15 m Low Pass filter, and I would suspect the bandpass
> filter as the most
> > likely.
> >
> > Look first at the slugs of L10 and L11 - they should be about the same
> > distance down from the top of the cans - if they are not, check
> capacitors
> > C30, C31, C35 and C36 for proper values and proper soldering.
> >
> > If the slugs are the same distance down in the cans (within a
> half turn),
> > then check the trimmers C32 and C34.  The trimmers will normally be set
> > close (within 20 degrees of rotation) to the midpoint - the slots in the
> > trimmers perpendicular to the flat side.  If that is not the
> case (and the
> > checks above for the 15 meter tuning are correct), then the most likely
> > thing is a soldering problem at relay K6 or trimmer capacitors
> C32 and C34.
> >
> > Look at the RF Board schematic sheet 3, and on the left side
> find the 15/17m
> > bandpass filter.  Check all the components shown in that
> schematic area for
> > proper soldering and correct values.  Include relay K6.
> >
> > 73,
> > Don W3FPR
> >
> >
> >> -----Original Message-----
> >>
> >> I have completed Transmitter alignment.  With the power set to
> two watts
> >> - I get 2 watts or better on all bands except 17 where I get only .5
> >> watts out regardless of the power setting.
> >>
> >> Any help appreciated.
> >>
> >> Thanks,
> >>
> >> Doug -- K0DXV
> >>
> >>
> >
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>
>
>
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