[AMRadio] Old Mica Caps in OLD VFOs

JAMES HANLON knjhanlon at msn.com
Thu Oct 25 14:28:01 EDT 2012

In my experience, I have not had a problem with old mica caps in old vfos.  I have two Johnson 122 vfos that show a bit of thermal drift, but no other problems.  I have two Heath VF1a that are more stable than the Johnson 122s.  I have two Knight VFOs that are also more stable than the Johnsons.  I have a DX-100 and a Valiant.  The DX-100 is quite stable, while the Valiant shows the same kind of slow, thermal drift that the Johnson VFOs do.  I also have a Millen 90711 vfo, a Harvey Wells Bandmaster vfo, a Geloso vfo, a Heath HG-10, tow Hallicrafters HT-18s, and vfos in a Knight T-150A, Elmac A-54, AF-67 and AF-68, Lysco 600, Heath TX-1, and three ptos from the T195 transmitter.  None of them show any obvious capacitor problems.
This is not to say that an individual unit may not have a problem, but I certainly would not advise wholesale replacement of the mica caps in an old vfo before I tried it out.
Jim Hanlon, W8KGI 		 	   		  

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