New K2 Owner and a few questions

[m0bmn]

Hi All

Just to say Hello, I asked a few days ago if anyone wanted to do a deal with
a ft857/icom 703 for a K2 well,

I had many offers to sell me a K2 so many thanks to all the people that made
the offer.

In the end I bought one from a member of the list and have today had chance
to play with it.

I have a FT1000MP Mk5 Field here in the shack and have been doing side by
side tests with the K2

I must say I am very surprised by how well this little radio works,

First SSB, it seems just about on par with the MP ,if anything many signals
sounded nicer to listen to on the K2!

Now CW

Well I was shocked! The MP is loaded with all the Yaesu filters, Has DSP
filtering too, I found a weak signal and switched between the two radios,

every time the K2 was better, the MP sounded hollow on Cw, well that’s the
best way I can describe it, but the K2 just sounded solid ,

I know which radio I will turning on first now!
NOW THE QUESTIONS

What current level is set on most K2 to avoid the Hi Cur warning, I get it
on a whisle, I have just for now set it to abou 4.5Amps and it seems ok with
that. ( 15 watts o/p )

I have a little noise on the vol pot when I turn it, a friend has the same
on his K2, is there a good way of cleaning the pot?

Well that’s about it (for Now)

One very happy K2 Owner

73

Paul

M0BMN


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[Ron D'Eau Claire-2]

Congratulations Paul:

My K2 is set for 3.8 amps. I don't recall how close that is to getting an
overcurrent. I have the KPA100 amp on mine so it may not need to run the
low-power section as hot as it might barefoot. I'd not be worried if 4.5
amps does the job for you.

NOTE: It is NOT recommended to run the K2 over 10 watts PEP sideband. It
won't hurt the K2, but distortion level rises above the 10 watt PEP level
the output stages are designed for. Of course, putting the "pedal to the
metal" isn't a problem on CW.

What's the serial number of your K2? If it's < 3000, do you know of the
volume control mod was done to it? The earlier K2's (like my S/N 1289) had a
different volume control circuit that used the control as a shunt resistance
across a balanced audio line. That works well enough, but it was found that
many controls started to sound scratchy quite soon with only normal wear.
Elecraft redesigned that circuit to use the volume control in a more normal
circuit that avoids that problem. As a bonus, the modified circuit also
exhibits the logarithmic response other volume controls do. If it hasn't
been modified, or if you aren't sure, you can tell by looking at the p-c
board for some jumpers that were required. Details of the mod are documented
on the Elecraft site in an application note. See:
http://www.elecraft.com/Apps/K2_AF_pot/K2_AF_gain_app_note.htm

Check to see if that mod has been made before changing the pot. At S/N 3000
the PC boards were updated to incorporate that change, so you won't see the
mod if you have a newer K2.

That's one of the hidden features in the K2. You don't have to dump your
existing rig and build a new one to keep "current". An early K2 has the
ability to demonstrate every feature and meet ever spec that a
just-delivered K2 meets. As improvements and changes have been made,
Elecraft has documented each one and, if significant parts were required,
produced an upgrade kit for those owners who wanted to update their older
rigs.

I wonder if your appreciation of the sound has to do with the somewhat
"softer" shoulders on the K2 filters, compared with many of those in other
rigs. I've never liked the sound of the extremely steep-sided filters. They
modulate noise and signals hanging across those stopband frequencies and
produce artifacts in the bandpass. They're nice if one feels it's  critical
to "cuddle up" to an S-9 signal a few Hz away without hearing it, but I find
that's important so seldom that I'd never give up the nice sound of what I
consider the "really good" K2 filters for that ability. I'll admit that I
"cut my teeth" on the bands with receivers that were 6 kHz wide and being a
good op meant that one could copy a CW QSO while hearing several other QSO's
in the same bandpass. SSB isn't so critical since it become unintelligible
noise as one moves far enough off-frequency. At least these we don't hear
the howling cacophony of wall-to-wall carrier hetrodynes that dominated the
phone bands half a century ago!

Ron AC7AC



-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Paul Webb
Sent: Saturday, October 01, 2005 4:11 PM
To: [hidden email]
Subject: [Elecraft] New K2 Owner and a few questions


Hi All

Just to say Hello, I asked a few days ago if anyone wanted to do a deal with
a ft857/icom 703 for a K2 well,

I had many offers to sell me a K2 so many thanks to all the people that made
the offer.

In the end I bought one from a member of the list and have today had chance
to play with it.

I have a FT1000MP Mk5 Field here in the shack and have been doing side by
side tests with the K2

I must say I am very surprised by how well this little radio works,

First SSB, it seems just about on par with the MP ,if anything many signals
sounded nicer to listen to on the K2!

Now CW

Well I was shocked! The MP is loaded with all the Yaesu filters, Has DSP
filtering too, I found a weak signal and switched between the two radios,

every time the K2 was better, the MP sounded hollow on Cw, well that's the
best way I can describe it, but the K2 just sounded solid ,

I know which radio I will turning on first now!
NOW THE QUESTIONS

What current level is set on most K2 to avoid the Hi Cur warning, I get it
on a whisle, I have just for now set it to abou 4.5Amps and it seems ok with
that. ( 15 watts o/p )

I have a little noise on the vol pot when I turn it, a friend has the same
on his K2, is there a good way of cleaning the pot?

Well that's about it (for Now)

One very happy K2 Owner

73

Paul

M0BMN


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[Don Wilhelm-3]

Paul,

Congratulations on your K2 purchase.

The AF Gain pot noise first (it is the easiest).  If your serial number is
less than 3000, you should see if the alternative AF Gain wiring mod has
been installed - if not, I suggest installing it first.  In the process, you
may want to replace the AF Gain pot since you would have the front panel
removed.  Replacement pots are available from Elecraft at a modest price.
If your SN is 3000 or greater (or if the AF Gain wiring change has been
installed in SN <3000), the best solution is to simply replace the pot.  I
have not had much success with any of the pot cleaners that I have used in
the past (that is pre-Elecraft times, so they may have changed the
formulations, but I regress...)

Now for your problems - on the Hi-Cur message, there is likely a problem
somewhere.  If everything is operating correctly and you voltage supply to
the K2 is at 13.8 volts, you should be able to run the CAL CUR at 3.5 Amps
or less and have no HiCur message.  Preliminary steps to take follow:

First thing, check your power supply and its connections to be certain you
are maintaining at least 12.5 volts or more at full power output - tap
DISPLAY and then TUNE to see what voltage is indicated.  If your supply
voltage sags significantly, fix that first and your problem may go away.
Reason: the K2 continues to draw current to satisfy the power output level
you have requested, and if the voltage drops, the current must increase to
provide that current.  The K2 will operate with lower voltage, but it will
draw more current (this is different than many other rigs that simply will
not produce enough power at lower voltages).

If you have a K2/100, first remove the KPA100 and set Cal Cur to 3 Amps,
then check to see if you have the Hi-Cur indication while operating into a
dummy load and see if the base K2 is capable of producing 13 to 15 watts
output on all bands except 10 meters (and possibly 12 meters) where the
power out should be at least 10 watts.

If you can achieve that power output level with the base K2, all is well so
far and the problem is in the KPA100.  If you cannot get that power output
from the base K2, the first place to check is the Low Pass Filter.  Check
each toroid for the proper number of turns - count the turns that pass
throught the center of the toroid (it is not unusual for a builder to put an
extra turn on the core), then check the value of each capacitor in the LPF
(use the schematic to identify the proper capacitor and its value).  If all
is OK there, write another note to the reflector for additional help.

If the base K2 checks out OK, re-connect the KPA100 cables (with the KPA100
laying upside down on a box to the right of the K2), remove the shield (do
not remove the black screws that hold the shield clips in place), and check
the LPF of the KPA100 in the same manner as the checks for the base K2
(toroid turns and capacitor values).  If all is well with the Low Pass
Filter, next thing to check is the KPA100 bias adjustment - follow the
instructions in the KPA100 manual.  And then, check the balance and
calibration of the KPA100 wattmeter (again, as instructed in the manual).

If all the above is correct, you should be able to have an output from the
KPA100 with a CAL CUR setting of 3.5 Amps and have no Hi Cur messages.

73,
Don W3FPR

> -----Original Message-----
>
> In the end I bought one from a member of the list and have today
> had chance
> to play with it.
>
> (snip)
> NOW THE QUESTIONS
>
> What current level is set on most K2 to avoid the Hi Cur warning, I get it
> on a whisle, I have just for now set it to abou 4.5Amps and it
> seems ok with
> that. ( 15 watts o/p )
>
> I have a little noise on the vol pot when I turn it, a friend has the same
> on his K2, is there a good way of cleaning the pot?
>
> Well that’s about it (for Now)
>
> One very happy K2 Owner
>
> 73
>
> Paul
>
> M0BMN
>
>

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Checked by AVG Anti-Virus.
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