Posted by
bdenley on
Feb 21, 2012; 2:40am
URL: http://elecraft.85.s1.nabble.com/Re-KB1VBF-Re-K2-Hi-Current-still-tp7303283.html
Gary and Don:
No KAT2 installed: (I am building it but have not finished it yet)
There is about 3.53 volts on D9 when TUNE is pressed, 0 volts otherwise. I set the pow er level to 15 watts but, as I said before, roughly 20 watts comes out no matter what I set the power to, and the HI CUR warning is always there with "P 1.0" power indicated.
Do I check the MCU next? Is that on the Control Board? Could the KDSP2 board be causing a problem?
Thanks again guys!
Brian KB1VBF
----- Original Message -----
From: "Gary Surrency" <
[hidden email]>
To: "b denley" <
[hidden email]>
Sent: Monday, February 20, 2012 3:05:13 PM
Subject: KB1VBF Re: [Elecraft] [K2] Hi Current...still
Don't connect a KAT2, KAT100, or KPA100 until the power control problem is fixed, since any of those can have damage that affects the power control.
Damage to D9 on the RF board or to the VRFDET input pin 2 of the 18C452 MCU can cause a loss of power control too. If OK, there should be up to about 4VDC at the cathode of D9 when transmitting at full power (14-15 watts).
--
73, Gary AB7MY
=========
[hidden email] Elecraft Technical Support
On 2/20/2012 11:58 AM,
[hidden email] wrote:
Thanks Gary. The rig does put out power as it turns out (plenty in fact) but is not controlling that power. High power comes out at any power setting with the associated Hi Cur warning. See Don Wilhelm's latest advice below.
Brian KB1VBF
----- Original Message -----
From: "Gary Surrency" <
[hidden email]>
To:
[hidden email]
Cc: "Don Wilhelm" <
[hidden email]> , "b denley" <
[hidden email]> , "Wayne Burdick" <
[hidden email]> , "
[hidden email] Wilhelm" <
[hidden email]>
Sent: Monday, February 20, 2012 1:20:22 PM
Subject: KB1VBF Re: [Elecraft] [K2] Hi Current...still
Try all bands.
Make sure no relays have a soldering iron burn.
Check the t-r switch has no reversed diodes or Q2 is reversed. The pictorial in the back of the manual shows which way these parts go.
An open RFC6 will cause self oscillation. This part is under Q6 on the bottom of the RF board.
Check all parts are correct in the Q5-Q8 area.
Check D9's cathode has about 4VDC at 14-15w if the rig will produce that power level.
Check the BNC connector does not have a broken ground pin. I have seen that before.
--
73, Gary AB7MY
=========
[hidden email] Elecraft Technical Support
On 2/18/2012 10:33 PM, Don Wilhelm wrote:
<blockquote>
Brian,
Is this condition on one band, or does it exist on all bands?
The winding of T4 will affect all bands,
A Low Pass Filter problem will affect one or two bands.
Transmit into a 50 ohm dummy load - then:
Quickly measure the voltage at the base of Q7 or Q8 during a TUNE. It should be between 0.60 and 0.64 volts.
Count the turns on T4 carefully, the green winding should have 2 turns and the white winding should have 3 turns. The "link" wires should go from the front of the transformer directly to the back (they do not wrap through both holes)..
73,
Don W3FPR
On 2/18/2012 10:15 PM, Wayne Burdick wrote:
<blockquote>
Did you check the winding on the PA transformer? If the impedance were much too low, the current could be too high. Could also be excessive bias current. What's the current drain in transmit mode, key up (i.e. tapping XMIT but not the key)?
Wayne
N6KR
On Feb 18, 2012, at 7:09 PM,
[hidden email] wrote:
<blockquote>
After getting the HiCur message, I replaced the two PA transistors, the associated hardware, Q11 and Q13, and R50. Unfortunately I stll get the same message: HiCur when I press TUNE with power any higher than about 1.5 watts inot a 50 ohm dummy load. Any have any ideas about what else might cause this problem?
Brian KB1VBF
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