Don,
While in CAL FCTR, try the probe in TP3 and TP1 and TP2. If you have a
zero reading in all 3 places, you most likely have a bad probe.
Yes you might have a PLL problem, but that is not certain yet. One quick
check is to measure the resistance from the source of Q19 to ground. If
it is high or infinite, check the leads of RFC14 like you did for
RFC16. The normal resistance is a bit more than 270 ohms.
73,
Don W3FPR
On 9/27/2018 4:41 PM, Don Schroder wrote:
Don,
Thank you for the excellent advice! I went to the bottom of the board
and checked the resistance between the ends of RFC16. It was infinite,
so I rewound RFC16 and ensured the leads were cleaned good. After
reinstalling, I now have 4.~ votes at U6 pin 5, and 8.~ at pin 8. Pin
8 of the Thermistor Board has 8.~ volts, too.
Now, when I select CAL FCTR and enable the frequency counter, the
counter shows 00000.00. I believe this tells me there is a problem
with the PLL Reference Oscillator. I will continue to look at those
components. Any other suggestions?
Thanks!
Don, KE0PVQ
Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows 10
*From: *Don Wilhelm <mailto:donw...@embarqmail.com>
*Sent: *Thursday, September 27, 2018 1:34 PM
*To: *Don Schroder <mailto:donandde...@hotmail.com>;
elecraft@mailman.qth.net <mailto:elecraft@mailman.qth.net>
*Subject: *Re: [Elecraft] K2 Alignment and Test, Part II issues
Don,
You apparently have a problem with the thermistor board - or the 8 volts
to it.
A "voltage rail" are those PC traces that carry voltage to various parts
of the circuit.
In the K2, there is one for 12 volts, another for 8 volts and another
for 5 volts.
On the schematic they are labeled "12V", "8A" and "5V" respectively.
The main 8 volt and 5 volt regulators are on the Control Board. You will
find an "5B" voltage rail at the output of U8 on the RF Board and the
"8B" voltage is sourced at the output side of RFC16.
If you do not have 8 volts at the thermistor board pin 8, then
investigate the stripping and tinning of the RFC16 leads.
Once you have 8 volts at the thermistor board (RP3 position) pin 8, then
recheck the voltage at U6 pin 5 - it should be quite close to 4 volts.
73,
Don W3FPR
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