[Elecraft] 2 M Transverter Stabliization

[John Ragle]

     I recently built an XV144, and the LO was badly out of calibration. 
The crystal is marked 116.000, but the offset was about 15 kHz, totally 
uncorrectable with the K3 --> CONFIG --> XV 1 OFS, which manages +/- 
9.99 kHz. Elecraft quickly shipped me a "mod" which consists of a small, 
variable, inductor that goes in the RF circuit board at L19. In 
addition, I invested in the crystal oven, since my experience with the 
crystal oven in my ICOM910H has been quite satisfactory. This adds < $50 
to the purchase price of the XV144 kit.

     With the inductor at L19 (remember to remove the jumper by C65!) 
and with the oven in place, the offset is well within range of the K3 
adjustment. My casual observation is that the drift in the LO frequency 
is completely negligible. This observation stems from the fact that I 
was checked in to a New England net for about 45 minutes at 144.250 and 
noticed no change in dial setting for reception of the NCS. The 
instructions that come with the mod kit L19 suggest beginning with the 
top of the tuning slug flush with the top of the coil form. I found this 
setting to be quite critical, and ended up about 3/4 of a turn further 
out than suggested, with K3 --> CONFIG --> XV1 OFS set to 2.50 and a 
frequency counter reading of 144.25000 when the K3 dial was set to 
144.250. I have the J9 jumpers set so that the oven is ON when ever the 
K3 is on, and my K3 is on from about 6 AM to about 10 PM continuously, 
every day.

     I think the oven and L19 solve the two problems of drift and 
offset, at least in my XV144. I get ~20 W maximum from this XV144.

John Ragle -- W1ZI

=====

On 2/12/2011 5:18 PM, David Pratt wrote:
> As far as I know, Chuck, Wayne has this in hand.
>
> My own K144XV is unusable because of the amount of frequency drift I am
> getting.  If I do use my K144XV I find that I am repeatedly having to
> apologise for Elecraft. It drifts almost 100Hz for every 5 minutes I
> transmit. This might be okay for FM, but certainly not for other modes.
>
> 73 de David G4DMP
>
> In a recent message, Chuck Smallhouse<w7cs at theriver.com>  writes
>> I'm referring to some concerns described by inputs to the Elecraft
>> Reflector, about not only the stability but also L.O. calibration of
>> the 2 M xvrtr, K144XV and probably the XV144.   I wonder if in the
>> near future you might consider phase locking their L.O.s to a 10 MHz
>> OCXO.  I understand that there are some Beta units in the field that
>> are locking the K3's TCXO to 10 MHz (when can I get one?).  It would
>> also be great if you could do the same for your 2M xvrtrs, so that
>> they could be synched to the same stable source.
>
>
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