High current question

[NZ0T]

My K2/100 is indicating high current draw on a portion of 40 meters but only
on the antenna.  On the dummy load there is no problem.  It's not high SWR
as both antennas it happens with (double bazooka and ground mounted
Butternut vert) indicate low SWR on my MFJ analyzer, SWR meter and the K2.
This occurs at full power of around 100 watts.  Any ideas on what may be
causing this?  I'm using my Drake PS7 power supply which has more than
enough amperage and minimal voltage drop.

Thanks and 73,

Bill NZ0T


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[Jay Schwisow]

Bill,

I have had this problem twice.  Check and/or tighten all connections
around the 239 on the back of the amp.  Once it was a broken solder
connection on the  tab and another times the screws had come loose.

73's,

Jay - KT5E

Bill Carpenter wrote:

> My K2/100 is indicating high current draw on a portion of 40 meters
> but only on the antenna.  On the dummy load there is no problem.  It's
> not high SWR as both antennas it happens with (double bazooka and
> ground mounted Butternut vert) indicate low SWR on my MFJ analyzer,
> SWR meter and the K2. This occurs at full power of around 100 watts.  
> Any ideas on what may be causing this?  I'm using my Drake PS7 power
> supply which has more than enough amperage and minimal voltage drop.
>
> Thanks and 73,
>
> Bill NZ0T
>
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>
>

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[Karl Larsen]

Bill Carpenter wrote:
> My K2/100 is indicating high current draw on a portion of 40 meters
> but only on the antenna.  On the dummy load there is no problem.  It's
> not high SWR as both antennas it happens with (double bazooka and
> ground mounted Butternut vert) indicate low SWR on my MFJ analyzer,
> SWR meter and the K2.
    Hi Bill, it could be that rf is getting into your mike or mike line
and your transmitting noise that causes high input current. If you have
another receiver listen to it.

73 Karl

> This occurs at full power of around 100 watts.  Any ideas on what may
> be causing this?  I'm using my Drake PS7 power supply which has more
> than enough amperage and minimal voltage drop.
>
> Thanks and 73,
>
> Bill NZ0T
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
>

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[Don Wilhelm-3]

Bill,

Remember that the HI-CUR message is produced by the base K2 and not the
KPA100 current draw.
What it means is that the KPA100 output is on the low side of the requested
power and the base K2 is trying to ramp up the power to obtain full output,
but in the process the current level that you had set in CAL CUR has been
exceeded.

How low is the 'low SWR' on the troublesome portion of the band that you
obtained with your analyzer?  And more importantly, is the impedance
reactive?  While an SWR of 1.5 or even 2.0 is a low SWR, the effort required
to drive into that particular load may be more than that required to drive a
50 ohm non-reactive load.  If that particular load causes the KPA100 output
transistors to be loaded in such a way that the gain is reduced a bit, then
the base K2 must drive the amplifier harder to develop the 100 watt power
output.

If the condition proves to be tolerable, just bumping up the CAL CUR setting
a bit may be all that is required.

73,
Don W3FPR

> -----Original Message-----
>
> My K2/100 is indicating high current draw on a portion of 40
> meters but only
> on the antenna.  On the dummy load there is no problem.  It's not
> high SWR
> as both antennas it happens with (double bazooka and ground mounted
> Butternut vert) indicate low SWR on my MFJ analyzer, SWR meter
> and the K2.
> This occurs at full power of around 100 watts.  Any ideas on what may be
> causing this?  I'm using my Drake PS7 power supply which has more than
> enough amperage and minimal voltage drop.
>
> Thanks and 73,
>
> Bill NZ0T
>

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