[Elecraft] KSB2 problem status: befuddled

[W3FPR - Don Wilhelm]

Neal,

Just an additional note - I usually adjust the SSB Carrier balance by
looking at the RF output (with no audio signal) with my 'scope - I adjust
the carrier balance for minimum power output (compromising if necessary
between USB and LSB).  You should find the proper point near the mid-point
setting of the carrier balance pot.  If it is not near the midpoint, look
for some component misplaced or improper soldering.

73,
Don W3FPR

> -----Original Message-----
> Taking things in reverse order - go ahead and put the Noise Blanker itself
> back in rather than the 6 dB pad resistors. It will only affect
> the receive
> path and not the Transmit path.
>
> OK - your current draw at a constant 10 Watts output looks just
> fine to me.
> It is a bit unusual that your minimum current draw for 10 watts
> out is at 20
> meters - usually that will occur at 40 or 30 meters - but this
> does not look
> like a real problem to me (actually it indicates better efficiency than
> normal on the higher bands).
>
>
> so now that still leaves us with the original problem of excessive current
> draw in SSB mode.  Actually something is 'fishy' here, because an
> SSB signal
> with no audio will result in very little output power (and quite
> low current
> draw).  So my thinking now is that you do not have the SSB balance set
> properly - or there is something incorrect on the KSB2 board.  I
> know it is
> difficult to do, but do look again - particularly at the balanced
> modulator
> and those things shown around it in the schematic.  It does now seem that
> your problems are coming from the KSB2.  Just as a wild guess I must ask -
> did you remove C167 from the RF board when installing the KSB2?
> If you fail
> to remove it, that alone could explain the conditions you are seeing.
>
> 73,
> Don W3FPR
>
>
>
> > -----Original Message-----
> >
> > Hi all,
> >
> > Thanks for giving some ideas!
> >
> > I checked the resistors on the bottom of the ssb board, they are all
> > correct. I must say that trying to identify parts on the top of the
> > board is a real challenge, its so stuffed that its almost impossible!
> >
> > Don, I redid the output  amperage at 10 watts:
> > 80 - 2.68
> > 40 - 2.72
> > 30 - 2.28
> > 20 - 1.96
> > 17 - 2.42
> > 15 - 2.50
> > 12 - 2.24
> > 10 - 2.16
> >
> > At 10 watts on 40, the voltage on rx is 13.5 on tx its 12.9.
> >
> > The group is right, I did not notice the power output on lower than 17m
> > (which is 15 watts). On 15 through 10, highest output is 13.3 watts.
> >
> > Do I still need to investigate the 40m current usage?
> >
> > Do I need to replace the 3 resistors and jumper that I pulled out to
> > eliminate the noise blanker module from the mix of things to
> > investigate? I should have done one module and waited to know it worked
> > before doing a second one!
> >
> > Neal
> > On Feb 21, 2005, at 5:37 PM, W3FPR - Don Wilhelm wrote:
> >
> > > Neal,
> > >
> > > There may be nothing wrong with 40 meters after all - I had missed the
> > > point
> > > that you were setting the Power control to absolute max.  What is your
> > > power
> > > supply voltage?  13.8 volts is typical (13.6 on the display),
> and lower
> > > power supply voltages will result in increased current draw.  What is
> > > the
> > > voltage when you are seeing a current of 3 amps or greater?
> > >
> > > I don't have a straightforward answer here.  Can it be that your
> > > Carrier
> > > Balance is not correctly set and you are really generating more RF
> > > drive
> > > with SSB than with CW?
> > >
> > > It is not really a fair comparison to compare current draw from band
> > > to band
> > > with the Power control set all the way clockwise.  Set it to 10 watts
> > > and
> > > check the current drawn for each band and both CW and SSB modes.
> > > Actually SSB mode should draw little current without audio (if the
> > > carrier is
> > > balanced because there should be little or no RF output.
> > >
> > > 73,
> > > Don W3FPR
> > >
> > >> -----Original Message-----
> > >> Hi Don and all,
> > >>
> > >> I have spent the afternoon looking for where I could have made a
> > >> mistake on the 40m LPF circuit. I didn't find any obvious ones, the
> > >> toroids came from 'The guy de Toroids' but I counted them all anyway,
> > >> and they are (luckily!) correct. Same for capacitors. Did the run of
> > >> voltage checks and didn't notice anything really wrong.
> > >>
> > >> On cw, cranking the output knob to the max, the display readings for
> > >> current are
> > >> 80 3.22
> > >> 40 3.36
> > >> 30 2.84
> > >> 20 2.38
> > >> 17 3.08
> > >> 15 2.84
> > >> 12 2.62
> > >> 10 2.42
> > >>
> > >> Output reads over 15 watts in all cases, usually abt 15.2. This reads
> > >> pretty much the same with or without the SSB module installed.
> > >>
> > >> I take it from your comments that the fact that 40m is the highest cw
> > >> reading, its indicative of something wrong. Looked at LPF and BPF
> > >> areas. What should I expect on the amp readings, 2.35 on 40 and a
> > >> gradual increase as I go towards 10m?
> > >>
> > >> I could reinstall the resistors and jumper and take out the noise
> > >> blanker module as thats something put in yesterday, I take it that I
> > >> need to do that if I want to test without it?
> > >>
> > >> I have boosted cal cur to 4.0 and still can get hi cur signal with
> > >> output fully counterclockwise on both usb and lsb. I have been very
> > >> happy working cw all week as it is (set the cal cur to 3.5 and it
> > >> hasn't tripped yet).
> > >>
> > >> Any more ideas to look at?
> > >>
>