[Elecraft] [K2] VCO Aignment L30

[Don Wilhelm]

Andrew,

The 6 volt initial setting at 4000 kHz is an initial setting.  And like 
I said, your settings will work fine.
I prefer to see all voltages above 1.8 volts, so the voltage at 7000 kHz 
is a bit lower than my preference.

If you can use the L30 setting to increase the voltage, then do so, but 
if not, then adjust the turns spacing on T5.  Note that L30 and T5 are 
inductors in parallel, so adjusting one or the other will do the task 
just fine.

The upper voltage adjustment must be limited to less than 7.5 volts.  
Note that the maximum voltage is limited by the voltage to the U6 op 
amp, so voltages of 8 volts indicate that the voltage range has run to 
its limit - keep the high voltage below 7.5 volts.

In other words, increase the voltage at 4 MHz a bit in order to increase 
the voltage at 7 MHz a bit, but keep all the voltage within the range of 
7.5 volts to 1.5 volts.  Actually keeping the range between 6.5 volts 
and 1.8 volts is the preferred range.

73,
Don W3FPR
On 12/30/2012 10:17 PM, andrew wrote:
> Thanks for the reply Don.
>
> To clarify, I can increase the voltage by winding the core of L30 down from the top, in fact up to about 8v but not the minimum of 6.0v as per the instructions. Would using this method achieve the desired result or is spreading the primary windings on T5 a prerequisite?
>
> Many thanks
> Andrew
> vk6wax
>
> ---- Don Wilhelm <w3fpr at embarqmail.com> wrote:
>> Set the frequency that produces the highest voltage (4000 kHz) and
>> spread the turns of T5 a bit to increase the voltage at R30.  I would
>> suggest that you try setting it to about 6.5 volts.  Then go back and
>> see how much the voltage at 7000 Hz has increased.
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