[TowerTalk] AC operated relays for ant switching

w8ji.tom w8ji.tom@MCIONE.com
Thu, 28 Jan 1999 08:05:20 -0500


Hi Dan,

Great suggestion.....I would also worry about 120 vac running everywhere,
especially outside around the antenna wiring.
 
> I have a home built ant sw using relays w 110 a.c. coils. They work fine
and do
> not overheat with 24 v.d.c. on the coils. This, of course is much safer
than
> using the 110 a.c.

 I use  a back connected diode across each coil to keep the
> inductive h.v. spike on disconnect from damaging the selector sw. Haven't
found
> bypassing necessary if the diodes are slow speed power types like 1N4001
> series.

1N4000 series diodes may not be high speed diodes, but they still rectify
RF pretty well Dan. I use them on a regular basis for RF clamps to protect
HF receivers! They are used in the all the Ameritron amps as meter clamps,
and rectify RF well enough to generate harmonics (and change meter
readings) when they aren't bypassed. 

I'd bypass them.

73 Tom






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