K1 Acting up on 20M and 30M

[KG2JM.Elecraft]

I have K1 SN950 with the 4 band module, Antenna Tuner and battery
module.  It has been working like a champ for 3 years.  Now, it has
decided it does not want to transmit on 20 meters and weakly on 30M.

Radio works fine on all other bands.  Radio receives fine on all bands.
When I attempt to tune on 20M, it fails to get a match, drops power to
0.1 (no matter how high I initially set it) and reports "Plo".  If I go
in and check the SWR from the last tune (rx.x) it reports r0.0.  On 30M
I do get a tune, I get a reported SWR of r9.9.

If I check the antenna with a SWR Analyzer, it reports that the antenna
is about 1.7 at the frequency I am trying to use on 20M and about 2.1 on
30M.

I put a power meter in line with the radio:  It reports near zero output
on 20M, about half power on 30M and appropriate power on all other
bands.  If I swap out the antenna and put in a dummy load, the meter
shows R6.3 and about half power on 30M, and Plo again and no measurable
output on 20 M.

I manually cycle through all the relays --- per the troubleshooting
guide --- and they all are clicking --- none appear to be hung or dead.

Any Ideas?

Jerry - KG2JM
K1 - 950
K2 - 4550 (under construction)

       

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[Tom McCulloch]

Hi all,
  I was inside my power supply ( a Radio Shack 25 amp job)  today and
decided to increase the output voltage to 14.0 volts.  I thought this would
give me a bit of a boost in charging the internal battery of my K2 (low
power version with a few optional add-ons).

  I don't see anything wrong with operating at 14.0 volts (I only use the
battery in the field and operate from the PS from home), but I thought I'd
ask the list to be sure.  The display is showing 13.4 volts, which sounds
about right for 14.0 from the PS.

Thanks
Tom WB2QDG
K2 1103


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[WB3AAL]

Hi Jerry,

 I had the same problem last year. I had the early 4 band board. I purchased
the KFL1-4TRIMKIT. I tried to install the trimmers but I had a hard time. So
I just purchased another four band kit. Now the K1 works great from the
Appalachian Trail.

72 and Thanks,
Ron Polityka
WB3AAL
www.wb3aal.com
www.n3epa.org/

K1 - SN 01011
K2 - SN 01392



----- Original Message -----
From: <[hidden email]>
To: <[hidden email]>
Sent: Saturday, October 29, 2005 4:15 PM
Subject: [Elecraft] K1 Acting up on 20M and 30M

>
> I have K1 SN950 with the 4 band module, Antenna Tuner and battery
> module.  It has been working like a champ for 3 years.  Now, it has
> decided it does not want to transmit on 20 meters and weakly on 30M.
>
> Radio works fine on all other bands.  Radio receives fine on all bands.
> When I attempt to tune on 20M, it fails to get a match, drops power to
> 0.1 (no matter how high I initially set it) and reports "Plo".  If I go
> in and check the SWR from the last tune (rx.x) it reports r0.0.  On 30M
> I do get a tune, I get a reported SWR of r9.9.
>
> If I check the antenna with a SWR Analyzer, it reports that the antenna
> is about 1.7 at the frequency I am trying to use on 20M and about 2.1 on
> 30M.
>
> I put a power meter in line with the radio:  It reports near zero output
> on 20M, about half power on 30M and appropriate power on all other
> bands.  If I swap out the antenna and put in a dummy load, the meter
> shows R6.3 and about half power on 30M, and Plo again and no measurable
> output on 20 M.
>
> I manually cycle through all the relays --- per the troubleshooting
> guide --- and they all are clicking --- none appear to be hung or dead.
>
> Any Ideas?
>
> Jerry - KG2JM
> K1 - 950
> K2 - 4550 (under construction)
>
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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[Don Wilhelm-3]

Tom,

If your goal is to keep the internal battery fully charged, bump the PS
output up a bit more (to 14.4) - you apparently still have the older
protective SB530 diode in your K2 SN1103, for those with post SN3000 or
upgraded K2s the proper voltage will be 14.2 to 14.3 volts because diode D10
was changed to a lower forward drop 95SQ015 type.
If you want to be really correct, increase the voltage until the voltage at
the battery terminals is 13.8 volts at room temperature and with a fully
charged battery.  You may want ot set it to 14.4 volts and then check the
battery terminal voltage in a few days and refine the adjustment as
required.

The K2 is speced for up to a 15 volt supply voltage, so you will not hurt
anything with the increased voltage.

73,
Don W3FPR

> -----Original Message-----
>
>
> Hi all,
>   I was inside my power supply ( a Radio Shack 25 amp job)  today and
> decided to increase the output voltage to 14.0 volts.  I thought
> this would
> give me a bit of a boost in charging the internal battery of my K2 (low
> power version with a few optional add-ons).
>
>   I don't see anything wrong with operating at 14.0 volts (I only use the
> battery in the field and operate from the PS from home), but I
> thought I'd
> ask the list to be sure.  The display is showing 13.4 volts, which sounds
> about right for 14.0 from the PS.
>
> Thanks
> Tom WB2QDG
> K2 1103
>
>

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[Don Wilhelm-3]

Jerry,

Looking at the schematic for the 4 band filter board and the K1, I do not
see anything that is common between 30 meters and 20 meters unless it is bad
relay points (but not likely K1).

I would suggest that you try to localize the trouble area.  Use a 'scope or
RF probe and compare the RF Voltage levels on the 4 band board at the input
to the Premix Bandpass filter (P1 pins 1 and 2), then the output of the
Premix Bandpass filter (P1 pin 6) - compare the 40 meter band with 30 meters
and the 20 meter band with 15/17 meters.

If you get a reasonable comparison at those points, go on to check the input
to the RF bandpass filter (P2 pin 1) and then the output of the RF Bandpass
filter (P2 pin 8).

At some point, you should see the RF Voltages are substantially different,
and you should look between the points with good levels and the one with bad
levels for the problem.

73,
Don W3FPR

> -----Original Message-----

>
> I have K1 SN950 with the 4 band module, Antenna Tuner and battery
> module.  It has been working like a champ for 3 years.  Now, it has
> decided it does not want to transmit on 20 meters and weakly on 30M.
>
> Radio works fine on all other bands.  Radio receives fine on all bands.
> When I attempt to tune on 20M, it fails to get a match, drops power to
> 0.1 (no matter how high I initially set it) and reports "Plo".  If I go
> in and check the SWR from the last tune (rx.x) it reports r0.0.  On 30M
> I do get a tune, I get a reported SWR of r9.9.
>
> If I check the antenna with a SWR Analyzer, it reports that the antenna
> is about 1.7 at the frequency I am trying to use on 20M and about 2.1 on
> 30M.
>
> I put a power meter in line with the radio:  It reports near zero output
> on 20M, about half power on 30M and appropriate power on all other
> bands.  If I swap out the antenna and put in a dummy load, the meter
> shows R6.3 and about half power on 30M, and Plo again and no measurable
> output on 20 M.
>
> I manually cycle through all the relays --- per the troubleshooting
> guide --- and they all are clicking --- none appear to be hung or dead.
>
> Any Ideas?
>
> Jerry - KG2JM
> K1 - 950
> K2 - 4550 (under construction)
>
>
>

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