I just looked at the current values of my K3s using the internal DISP
current and voltage values.
This is how it came from the factory after replacement of the KPA3A rev
E amp on 5/30/2018.
In RX USB mode = 1.6A Vcc = 13.8V Audio volume at minimum.
In TX USB mode no audio, 10 watt PWR setting = 1.60A
In TX USB mode no audio, 100 watt PWR setting = 2.91A
The PWR delta is 1.31 amps
In RX CW mode, = 1.03A Vcc 13.8V Audio volume at minimum.
In TX CW mode PTT closed, key open, 10 watt PWR setting 1.54A Vcc 13.7V
In TX XW mode, PTT closed, key open, 100 watt PWR setting 2.85A Vcc 13.6V
The PWR delta is 1.31 amps
Your values may be different if you have the 2nd receiver and can vary
depending on your Vcc.
73
Bob, K4TAX
On 3/7/2019 12:34 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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