RE: K2 weird problem

[Gregg mulder]

Just wanted to let all of the folks assisting me with this problem, what i found. Yes the problem appeared to be somthing not right with Q1 on the ssb brd. After replcing Q1,Q2,Q3, and a dozen or so associated components, i started tracing signals. When sigs at ALC threshold on U2 (Max 522) didn't match the sig on emitter of Q1, i noticed that this signal gets routed from the top of the brd down to the bottem of the brd thru an empty thru-hole plated hole. When i soldered that empty thru hole full of solder, i got this problem to go away. Apparently the thru -hole plating had an intermittent connection. This explains why it would somtimes work with the brd just plugged in (not screwed down) es the when tightened down, quit working. ( flex on the brd opened the ckt) It would seem that the thru hole plating on this particular ckt brd was not up to par, or had opened up during shipping. So this problem is fixed. Now ive got other problems. Don't think they are related. Power
 out put drops off seriosly on 20 15 es 10 meters  20, max pwr out = 5 w. 15 = 1 w. 10 = less than 1 watt. May just be improper alignment. I'll let you know what i find. Suggestions wellcome. I'd like to agn thank all of the fine people on this reflector for all ur help.  The caliber of support for Elecraft products is exceptional, and i have confidence that this rig will be playing as it should very soon.      VY 73's to all, Gregg Mulder
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[srife]

Good goin' Gregg.  Glad you were able to track that down...must have been a tough one. Good luck with the tune up and hope everthing goes smooth from here.
   
   
  Stan
  W5EWA
  Houston
 

Gregg mulder <[hidden email]> wrote:
  Just wanted to let all of the folks assisting me with this problem, what i found. Yes the problem appeared to be somthing not right with Q1 on the ssb brd. After replcing Q1,Q2,Q3, and a dozen or so associated components, i started tracing signals. When sigs at ALC threshold on U2 (Max 522) didn't match the sig on emitter of Q1, i noticed that this signal gets routed from the top of the brd down to the bottem of the brd thru an empty thru-hole plated hole. When i soldered that empty thru hole full of solder, i got this problem to go away. Apparently the thru -hole plating had an intermittent connection. This explains why it would somtimes work with the brd just plugged in (not screwed down) es the when tightened down, quit working. ( flex on the brd opened the ckt) It would seem that the thru hole plating on this particular ckt brd was not up to par, or had opened up during shipping. So this problem is fixed. Now ive got other problems. Don't think they are related. Power
out put drops off seriosly on 20 15 es 10 meters 20, max pwr out = 5 w. 15 = 1 w. 10 = less than 1 watt. May just be improper alignment. I'll let you know what i find. Suggestions wellcome. I'd like to agn thank all of the fine people on this reflector for all ur help. The caliber of support for Elecraft products is exceptional, and i have confidence that this rig will be playing as it should very soon. VY 73's to all, Gregg Mulder
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[Don Wilhelm-3]

Gregg,

Glad to hear you have the KSB2 problem licked - that was a tough one!

On your power output on the higher bands, the first thing to check is T2 -
it should have the correct number of turns and look just like the diagram in
the manual - it is also good to space this transformer above the board by
about 1/8 inch - it will self support on its own leads.

T4 is another possibility and T1 as well.  Is there any chance that T4 is
installed backwards?  Are the two links on T4 installed correctly?  Are both
Z1 and Z2 in place? C127 and C128 should be installed correctly, well
soldered and should be 680 pf.

If all that checks out, try comparing the RF Voltage produced by a normal
output band with one of the low output bands (turn the power all the way up
when doing that test) - check at several points along the transmit chain -
Q5 base (junction of R40 and R41 can be reached from the top), Q5 collector
(case), Q6 base, Q6 collector, Q7/8 base and if you are using a 'scope with
an 10X probe, the collector of Q7/8 (do not measure that with an RF Probe,
the diode may be zapped by the RF Voltage).

Due to the way the K2 power control circuits work, you can expect to see a
higher RF voltage on the 'bad' bands than the 'good' bands up to the point
where the problem exists.  Again, crank the power up to full when doing this
comparison test - if you leave it low, everything may look good on all bands
and your testing will be inconclusive.

73,
Don W3FPR

> -----Original Message-----
 Now ive got other problems.
> Don't think they are related. Power
>  out put drops off seriosly on 20 15 es 10 meters  20, max pwr
> out = 5 w. 15 = 1 w. 10 = less than 1 watt. May just be improper
> alignment. I'll let you know what i find. Suggestions wellcome.
> I'd like to agn thank all of the fine people on this reflector
> for all ur help.  The caliber of support for Elecraft products is
> exceptional, and i have confidence that this rig will be playing
> as it should very soon.      VY 73's to all, Gregg Mulder
>
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