K2: VFO control voltage problem.

classic Classic list List threaded Threaded
2 messages Options
Reply | Threaded
Open this post in threaded view
|

K2: VFO control voltage problem.

Thomas-174
Hello.
I know this has been covered before, but I could not find anything at this time.
I have 7.56V on 30M, 20M, 17M, 12M and 10M both on low and high part of the bands.
On 3.50MHz I can't get the VFO voltage above about 3V, same on 21MHz.
On 7.0MHz I got aprox. 6V vhile on 7.3 I got aprox. 7,56V.
I have re-checked the capacitors C71 to C74 and the values are corect.
I have vound the transformer T5 as on the drawing and several pictures on the internet,but it seems like it migth need another turn or 2?

73 de Thomas LA3PNA
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
Reply | Threaded
Open this post in threaded view
|

Re: K2: VFO control voltage problem.

Don Wilhelm-4
Thomas,

What is the voltage when you tune to 4000 kHz?  That is the starting
point for adjustment and it should be near 6 volts.

After obtaining 6 volts at 4000 kHz, do a quick check at 7000 kHz - that
voltage should be in the 1.5 to 2.2 volt range if all is well.

After that, check the other band edges.

If the voltages do not fall in line as above, you have some
troubleshooting to do.  In addition to T5, check the varactors to be
certain they are the correct ones in the correct places, and that
everything is soldered well.

If you still have trouble, measure the VCO frequency with the internal
counter probe connected to TP1 when you tune to 4000kHz and when tuned
to 3.5 MHz and let us know what those frequency readings are as well as
the corresponding R30 voltages.

73,
Don W3FPR

Thomas wrote:

> Hello.
> I know this has been covered before, but I could not find anything at this time.
> I have 7.56V on 30M, 20M, 17M, 12M and 10M both on low and high part of the bands.
> On 3.50MHz I can't get the VFO voltage above about 3V, same on 21MHz.
> On 7.0MHz I got aprox. 6V vhile on 7.3 I got aprox. 7,56V.
> I have re-checked the capacitors C71 to C74 and the values are corect.
> I have vound the transformer T5 as on the drawing and several pictures on the internet,but it seems like it migth need another turn or 2?
>
> 73 de Thomas LA3PNA
>
>  
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com