[Elecraft] [K2] Odd "Hi Refl"/high current problem only in TUNE

2017-04-20 Thread Jim Allen 
Any more info on this?

73 Jim Allen W6OGC 
> 25 amps at 14 volts is 350 watts. That is an awful lot for a radio that is 
> supposed to be putting out only 20. I would expect at most 2 to 3 watts drain 
> at 20 watts TX output. Something is definitely going on here. may load While 
> I don’t suspect the antenna, have you tried testing into a good 50 ohm dummy 
> load to see if you can duplicate the issue? You might also look for bad 
> solder joints between the PA transistors and the antenna. And, just in case, 
> check to make sure there are no bad (arcing) connectors in the antenna path. 
> Perhaps W3FPR might be around on the Easter Sunday for some suggestions? - 
> Jack, W6FB
> > On Apr 16, 2017, at 7:51 AM, Steve Kavanagh via Elecraft  > mailman.qth.net> wrote: > > This one cropped up just today, with no 
> > significant change in my home station setup, using a K2/100 on 40m using a 
> > low inverted Vee. > > Sometimes (typically every other or every third time, 
> > but randomly), when pushing (and holding) the tune button with the power 
> > set to 11 watts or more, I get a high reflected power message on an antenna 
> > which is matched at low power. The power supply voltage reads about the 
> > normal 14V and the ammeter in the power supply is pinned at 25 A (or more) 
> > when this happens. An external SWR meter reads lots of reflected power. 
> > Everything unplugged from the rig except the power cable and the coax to 
> > the external SWR meter/antenna tuner/antenna. It's fine on a dummy load. > 
> > > I'd suspect a simple RF feedback problem, except that with 100 watts of 
> > CW everything is perfectly normal. The problem occurs only when using the 
> > tune button around the nominal tune-mode 20 watts, so the external SWR 
> > meter reading implies that the PA is probably oscillating at some frequency 
> > where the antenna is not matched. I haven't tried any other bands yet, but 
> > since there does seem to be RF feedback involved, I'm not sure they will 
> > tell me much of a diagnostic nature. > > Any ideas as to what might be 
> > happening and how to stop it? > > 73, > Steve VE3SMA > 
> 
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Re: [Elecraft] [K2] Odd "Hi Refl"/high current problem only in TUNE

2017-04-16 Thread Jack Brindle 
25 amps at 14 volts is 350 watts. That is an awful lot for a radio that is 
supposed to be putting out only 20. I would expect at most 2 to 3 watts drain 
at 20 watts TX output. Something is definitely going on here.
may load While I don’t suspect the antenna, have you tried testing into a good 
50 ohm dummy load to see if you can duplicate the issue? You might also look 
for bad solder joints between the PA transistors and
the antenna. And, just in case, check to make sure there are no bad (arcing) 
connectors in the antenna path.

Perhaps W3FPR might be around on the Easter Sunday for some suggestions?

- Jack, W6FB


> On Apr 16, 2017, at 7:51 AM, Steve Kavanagh via Elecraft 
>  wrote:
> 
> This one cropped up just today, with no significant change in my home station 
> setup, using a K2/100 on 40m using a low inverted Vee.
> 
> Sometimes (typically every other or every third time, but randomly), when 
> pushing (and holding) the tune button with the power set to 11 watts or more, 
> I get a high reflected power message on an antenna which is matched at low 
> power.  The power supply voltage reads about the normal 14V and the ammeter 
> in the power supply is pinned at 25 A (or more) when this happens.  An 
> external SWR meter reads lots of reflected power.  Everything unplugged from 
> the rig except the power cable and the coax to the external SWR meter/antenna 
> tuner/antenna. It's fine on a dummy load.
> 
> I'd suspect a simple RF feedback problem, except that with 100 watts of CW 
> everything is perfectly normal.  The problem occurs only when using the tune 
> button around the nominal tune-mode 20 watts, so the external SWR meter 
> reading implies that the PA is probably oscillating at some frequency where 
> the antenna is not matched.  I haven't tried any other bands yet, but since 
> there does seem to be RF feedback involved, I'm not sure they will tell me 
> much of a diagnostic nature.
> 
> Any ideas as to what might be happening and how to stop it?
> 
> 73,
> Steve VE3SMA
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Re: [Elecraft] [K2] Odd "Hi Refl"/high current problem only in TUNE

2017-04-16 Thread Guy Olinger K2AV 
Sounds more to me like an arc out in feedline/antenna somewhere. While the
arc is flashed, the feed Z goes very low. And the SWR therefore goes very
high. And it takes less energy to continue the arc than to start it.

The key here is that the SWR changes when the trouble starts.

An antenna is constantly subject to mechanical stress. One thing you can
count on with any antenna you put up is that it will fail at some point and
require maintenance. It's not if, it's when and how.

73, Guy K2AV

On Sun, Apr 16, 2017 at 10:52 AM Steve Kavanagh via Elecraft <
elecraft@mailman.qth.net> wrote:

> This one cropped up just today, with no significant change in my home
> station setup, using a K2/100 on 40m using a low inverted Vee.
>
> Sometimes (typically every other or every third time, but randomly), when
> pushing (and holding) the tune button with the power set to 11 watts or
> more, I get a high reflected power message on an antenna which is matched
> at low power.  The power supply voltage reads about the normal 14V and the
> ammeter in the power supply is pinned at 25 A (or more) when this happens.
> An external SWR meter reads lots of reflected power.  Everything unplugged
> from the rig except the power cable and the coax to the external SWR
> meter/antenna tuner/antenna. It's fine on a dummy load.
>
> I'd suspect a simple RF feedback problem, except that with 100 watts of CW
> everything is perfectly normal.  The problem occurs only when using the
> tune button around the nominal tune-mode 20 watts, so the external SWR
> meter reading implies that the PA is probably oscillating at some frequency
> where the antenna is not matched.  I haven't tried any other bands yet, but
> since there does seem to be RF feedback involved, I'm not sure they will
> tell me much of a diagnostic nature.
>
> Any ideas as to what might be happening and how to stop it?
>
> 73,
> Steve VE3SMA
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> Help: http://mailman.qth.net/mmfaq.htm
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[Elecraft] [K2] Odd "Hi Refl"/high current problem only in TUNE

2017-04-16 Thread Steve Kavanagh via Elecraft 
This one cropped up just today, with no significant change in my home station 
setup, using a K2/100 on 40m using a low inverted Vee.

Sometimes (typically every other or every third time, but randomly), when 
pushing (and holding) the tune button with the power set to 11 watts or more, I 
get a high reflected power message on an antenna which is matched at low power. 
 The power supply voltage reads about the normal 14V and the ammeter in the 
power supply is pinned at 25 A (or more) when this happens.  An external SWR 
meter reads lots of reflected power.  Everything unplugged from the rig except 
the power cable and the coax to the external SWR meter/antenna tuner/antenna. 
It's fine on a dummy load.

I'd suspect a simple RF feedback problem, except that with 100 watts of CW 
everything is perfectly normal.  The problem occurs only when using the tune 
button around the nominal tune-mode 20 watts, so the external SWR meter reading 
implies that the PA is probably oscillating at some frequency where the antenna 
is not matched.  I haven't tried any other bands yet, but since there does seem 
to be RF feedback involved, I'm not sure they will tell me much of a diagnostic 
nature.

Any ideas as to what might be happening and how to stop it?

73,
Steve VE3SMA
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