[Elecraft] NG0R - K2+K60XV+XV144/222/432 - Setup Issue #2

[John Hoaglun]

Hi Don & the list,

I am making some slow progress on the 432 transverter setup.

Initially TP6 was almost nill so I hooked up the Oscope and worked my
way from the IF-In to the Mixer. The 28MHz band pass looked suspect,
specifically C52/C54 as the drop at each capacitor was pretty sharp even
for a BP filter. I replaced them with fresh 150pF caps that I had on
hand. That improved the situation but my levels were still low measured
at TP5, TP6, and the output with an RF meter, and analyzer.

I tried tuning up the filters with using the analyzer & rf meter. That
once again slightly improved things but not enough to quantify.

I reset the PA bias back to the 20mV and then went to TP6 again. I was
able to very slowly move from almost 0 to 2V by working my way thru the
filters and then going back thru it again several times

TP3/TP4 20mV 
PA voltage 2.35V & 13.7V
TP5 0V
T6 2.05V
U6 Output pin 4.97V

My 60MHz Oscope is not fast enough to make a good measurements at U6
IN/OUT and U7 IN/OUT but it does not appear that I am seeing enough gain
at U6. I suspect that U6 is not driving U7 hard enough for U7 do any
work. 

Any suggestions how to test this?

What else should I be looking at & testing?

Thanks, JH
 
-- 
John Hoaglun
NG0R - EN25
http://www.hoaglun.com



On Sat, 2010-08-21 at 09:07 -0400, Don Wilhelm wrote:

> John,
> 
> On the XV432, can you vary the DC voltage measured at TP6 when you 
> adjust the Input Attenuator?  TP6 is a built-in RF probe which measures 
> the RF voltage at the output of U6.  If you can see that voltage change 
> when adjusting the input attenuator, you can use it for peaking the 
> bandpass filters.
> On the XV222, there is no TP6, but you can use an external RF Probe to 
> do the same thing.
> If there is no output from U6, try the input.  The first step to your 
> troubleshooting is to determine what works, and secondly to discover 
> where in the chain of events the failure occurs.
> 
> 73,
> Don W3FPR
> 
> John Hoaglun wrote:
> > Hi Don & group
> >
> > I tried using a low pass filter between the K60XV and the 432
> > transverter and went thru the tune-up from scratch with similar results.
> > I removed the LP filter.
> >
> > I measured the K60XV out at -3dBM or about 50mW which what I say last
> > night as well. I put it on my counter & analyzer and notice that it
> > there is something at 18MHz that is about +8-10 dB louder than the 28MHz
> > IF.  --Interesting note.
> >
> > I then tried your second suggestion:  I reconfigured the transverter for
> > a high power IF input,  JP3/JP4 2-3, and JP5/JP6 1-2, and the associated
> > menu settings.  Using port A on the radio I tried rerunning the
> > transverter setup and got similar results.
> >
> > Common theme: TP5 has almost no reading on it while adjusting R22.
> > Adjusting the inductors does not cause a significant change in TP5.  (I
> > can see it on the analyzer with a directional coupler on the output but
> > it is a TINY signal.)
> >
> >
> >