Chuck,
True, but make sure that current is being distributed equally between
the 2 devices. Set both pots to full CCW and then adjust one for a
400-500ma rise, then adjust the other for another 400-500ma rise.
You should then have a 1 amp rise total, but you will be assured that
each device is drawing the proper amount of idle current.
73,
Don W3FPR
On 3/7/2019 1:34 PM, hawley, charles j jr wrote:
Could you be mistaken on my procedure? The 1 amp plus or minus is
typical with three K3s es that I know of. There are two devices and
two trim pots.
This instruction is only for one device since he says "the BIAS pot" I
believe...
"If there is much more current than this, set the BIAS pot to minimum
(fully counter clockwise). Then tap XMIT (not TUNE) and note what the
current is in VFO B's readout. Slowly turn up the BIAS pot until you see
400-500mA more current that was seen with the BIAS pot at minimum."
I am looking at the total current accessible from DISP and read out on
the front panel. First I go to the LPA only, read the total current
drawn by the rig under XMIT SSB(no modulation) and then engage the KPA
by turning up the power knob and I subtract the first reading from the
second. I get about 1.05 amps.
Am I close to knowing the total current into the KPA this way?
I feel that this important knowledge about how to set up the amp is
fuzzy or not well known...the why I asked the question.
Thanks for the replies!!
Chuck Hawley
[email protected]
Amateur Radio, KE9UW
aka Jack, BMW Motorcycles
------------------------------------------------------------------------
*From:* Don Wilhelm <[email protected]>
*Sent:* Thursday, March 7, 2019 12:10 PM
*To:* hawley, charles j jr; [email protected]; Mike Harris
*Subject:* Re: [Elecraft] Fwd: AW: K3 KPA3 bias adjust
Chuck,
The instruction cited was for a 400-500 ma rise TOTAL (not per device).
So I conclude your bias is set too high or there is a problem in the
bias circuit.
73,
Don W3FPR
On 3/7/2019 9:31 AM, hawley, charles j jr wrote:
> Thanks for the info. Using xmit for the low power amp and then going
to the high power amp shows a difference of 1.05A. So my devices are
showing about 500+ ma each. In the ball park.
> Thanks so much for the reply.
>
> Chuck Hawley
> [email protected]
>
> Amateur Radio, KE9UW
> aka Jack, BMW Motorcycles
>
> ________________________________
> From: [email protected]
<[email protected]> on behalf of Mike Harris via
Elecraft <[email protected]>
> Sent: Thursday, March 7, 2019 5:43 AM
> To: [email protected]
> Subject: [Elecraft] Fwd: AW: K3 KPA3 bias adjust
>
> Hi,
>
> Forwarded a 2009 email exchange for your info. I have NOT tried this so
> use with care and at your own risk.
>
> Regards,
>
> Mike VP8NO
>
>
> -------- Forwarded Message --------
> Subject: AW: [Elecraft] K3 KPA3 bias adjust
> Date: Sat, 3 Jan 2009 19:46:55 +0100
> From: Koppendorfer Klaus <[email protected]>
> To: Jan Erik Holm <[email protected]>
> CC: [email protected] <[email protected]>
>
> Locate the BIAS pot at the front of the KPA3, between the heat sink and
> the KPA3 shield. Note what the display current is in the VFO B readout
> when you tap the Display button and turn the VFO B knob to the current
> readout. In RX, it should be 1.0A or so. In XMIT (not TUNE), it should
> be about 1.90 to 2.0A when the Power knob is set to 12w or above so the
> KPA3 is made active (but there is no RF output since XMIT is used). Or
> you can press the PTT button but do not speak.
>
> If there is much more current than this, set the BIAS pot to minimum
> (fully counter clockwise). Then tap XMIT (not TUNE) and note what the
> current is in VFO B's readout. Slowly turn up the BIAS pot until you see
> 400-500mA more current that was seen with the BIAS pot at minimum.
>
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