DX-60 Function switch/ Mod.

[Gerald Lemay]

Mode switch contact failure seems to be the most common failure I know of in
DX-60's. There has been a number of postings on the list addressing this
subject. I doubt if the 10K resistor will fix the problem. The reason DX-60
function switch contacts burn up over time is due to arcing across the
switch contacts. It's NEVER a good idea to switch high DC voltages or
voltages with large DC components. In the event there is no other recourse,
then you should use what is called a snubber across the switch contacts. A
snubber consists of a series resistor/capacitor combination which tries to
absorb the energy causing the arc to occur. It doesn't completely suppress
the arc but reduces the energy and helps prolong contact life. The
Hallicrafters HT-40 transmitter which is in the same class as the DX-60 has
a 1K resistor and 0.005uF capacitor across the switch contacts. The Eico
720, also in the same class has a 1K resistor and a 0.001uF/2KV capacitor in
a similar arrangement. So before you do anything, try either solution. If
the contacts have completely burned off, the chances of finding a
replacement is virtually nil, short of getting your hands on a parts unit. A
good solution is to rebuild the switch with contacts from another more
commonly found switch. I've used eyeglass repair kits to secure the new
contacts on the wafer. It's not hard to do, just tedious. But when you get
done and add a snubber, you'll be set for a very long time.

-----Original Message-----
From: Heathkit Owners and Collectors List
[mailto:HEATH at LISTSERV.TEMPE.GOV]On Behalf Of Earle Bulicek
Sent: Sunday, March 18, 2001 1:25 PM
To: HEATH at LISTSERV.TEMPE.GOV
Subject: DX-60 Function switch/ Mod.


Hi all:  It has been suggested to me that the placement of 10 Watt / 10K
resistor to ground on the high voltage near the rotary switch will stop the
arcing and thus extend the life of the contacts.  Has anyone done this?
Anyother mods, suggestions, ideas, etc.
CUL
Earle

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