K3/K144XV/K3EXREF problem

[k2ua]

Greetings, all.

I have a K3 with the KSYN3A synthesizers, K3EXREF external reference
option, and the K144XV internal 2-meter transverter. The K144XV also has
the internal PLL lock option board installed.

With this setup, I am trying to solve two problems: (1) knowing my 2-meter
frequency exactly, and (2) the 2-meter transverter drifts a lot when it
gets warm in MSK144 and FTx operation even though I'm running it at about 3
watts output.

The reference oscillator input SMA connector is connected to a surplus
Spectracom GPS-locked reference. All signs indicate that the K3EXREF is
working properly. In the REF CAL menu, the asterisk between the REF and CAL
is blinking at a 1-Hz rate. The radio seems to be right on frequency based
on some checks on the HF bands with known-frequency signals.

The transverter is configured as XV1. Its offset is configured for 3.8 kHz,
which is (approximately) the offset printed on the transverter for 144 MHz.
When I set the XV1 OFS to REFLOCK (using the 0 button on the keypad), the
XV1 OFS changes to 0.05 and the radio goes way off frequency from where it
should be. So it does not seem that the reference oscillator is locking the
K144XV's LO properly--although it's also possible that it's locked, but has
the incorrect offset. I can't tell because the menus don't have a display
option for the K144XV reference lock status.

I am sure that the cables are connected correctly based on the installation
documentation.

I've had spotty results with Elecraft support (not exactly poor, but
consistently slow and weak), so I wanted to reach out here to see if anyone
has experienced this issue and may be able to shed some light on what I am
seeing. Thanks in advance.

--73, Rus, K2UA
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[Gary Hembree-2]

Have you performed the modification to the KREF3 that increases its output level to compensate for the increased load of the K144RFLK board?

Search on the Elecraft web site for:  “Elecraft KREF3 Output Level Modification” (pdf)
Order KREF3MDKT (51 Ohm SMD 0603 size and 75 ohm 1/4 watt leaded resistors)
https://ftp.elecraft.com/K3/Mod%20Notes%20Alerts/E740278%20KREF3%20Output%20Level%20Modification.pdf

Installing this modification solved a similar problem I was having with the K144XV, K144RFLK and K3EXREF when using them in a K3 that has a second receiver.  I have no drift now when running full power from the K144XV in MSK144 and FT8 to drive my old Mirage amplifier.

Another issue to be aware of is incorrect cable diagrams associated with the K144RFLK in some of the early documentation for installation of the KSYN3A synthesizers.  However, the radio will usually not work at all if the incorrect cable diagram is followed.  The correct diagram is contained in the following document.
https://ftp.elecraft.com/K3S/Manuals%20Downloads/E740257%20KSYN3A%20Installation%20Rev%20A6.pdf

73
Gary, N7IR
--------------------------------------------

Greetings, all.

I have a K3 with the KSYN3A synthesizers, K3EXREF external reference option, and the K144XV internal 2-meter transverter. The K144XV also has the internal PLL lock option board installed.

With this setup, I am trying to solve two problems: (1) knowing my 2-meter frequency exactly, and (2) the 2-meter transverter drifts a lot when it gets warm in MSK144 and FTx operation even though I'm running it at about 3 watts output.

The reference oscillator input SMA connector is connected to a surplus Spectracom GPS-locked reference. All signs indicate that the K3EXREF is working properly. In the REF CAL menu, the asterisk between the REF and CAL is blinking at a 1-Hz rate. The radio seems to be right on frequency based on some checks on the HF bands with known-frequency signals.

The transverter is configured as XV1. Its offset is configured for 3.8 kHz, which is (approximately) the offset printed on the transverter for 144 MHz. When I set the XV1 OFS to REFLOCK (using the 0 button on the keypad), the XV1 OFS changes to 0.05 and the radio goes way off frequency from where it should be. So it does not seem that the reference oscillator is locking the K144XV's LO properly--although it's also possible that it's locked, but has the incorrect offset. I can't tell because the menus don't have a display option for the K144XV reference lock status.

I am sure that the cables are connected correctly based on the installation documentation.

I've had spotty results with Elecraft support (not exactly poor, but consistently slow and weak), so I wanted to reach out here to see if anyone has experienced this issue and may be able to shed some light on what I am seeing. Thanks in advance.

--73, Rus, K2UA  


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