The K2’s VCO (voltage-controlled oscillator) may be susceptible to
low-frequency modulation by very large power transformers, such as
those in linear amp power supplies and antenna rotator controllers.
Such modulation can usually be eliminated by simply moving the
equipment away from the transceiver. In difficult cases, magnetic
shielding can be used, and we've created a modification kit for this
purpose (Order #K2VCOSHLDKT).
The mod kit provides a smaller replacement core for transformer T5, a
high-permeability ferrite sleeve, and associated hardware. The ferrite
sleeve is installed over T5, greatly reducing the effect of nearby
strong magnetic fields. In addition, slug-tuned inductor L30 must be
electrically disabled since it, too, is affected by magnetic fields.
With L30 out of the circuit, the VCO inductance can still be adjusted,
if necessary, by slightly squeezing or spreading the turns of T5.
The kit is priced at $10. For more information, see our parts order
page:
http://www.elecraft.com/order_form_parts.htm#K2%20Parts
73,
Wayne, N6KR
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http://www.elecraft.com
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