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UrgentSwedish questionsAnother question: I am just repairing for a =
friend a HEATH SB1000 and on 160 the switch contacts that connects the =
C26 270 pF doorknob are both burned. It seems that the switch could not =
take the current through this condenser? Is this a often found problem =
in this amplifier? Where do I find a new switch ? I am planning to let =
the new switch contacts actuate a small high frequency relay that =
handles this hf current??
This is an extremely common problem. It is a high voltage problem, =
not current.
You can probably get a switch from Ameritron. I bought several from =
Heath before
they went out of the ham business. Years ago, they were $118 each! =
Also Ameritron
has mica replacement caps. for the doorknobs in the tank circuit. =
This is another big
problem in the SB-1000. It has always been my theory that there is a =
Tesla coil
effect in the tank circuit. The switch probably did not burn out =
when the amp was
operating on 160m, but on 80m...just a guess based on my experience =
with the
SB-1000. Heath tried to minimize the failure rate on the band switch =
by having
the builder solder flat washers on certain contacts. Those that did =
not do that
lost their switches almost immediately, so that shows that the =
switch was not
a good choice for that particular layout.
The toroid on 160 is red not yellow, by the way. Any comments?
Red is a very good choice for an L coil for 160 and 80m. It takes =
fewer
turns of wire to get the desired inductance. I use the big red ones =
in
a couple of 8877 amps.
GL!
Phil, K5PC
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<HTML><HEAD><TITLE>UrgentSwedish questions</TITLE>
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0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
<BLOCKQUOTE>
<DIV>Another question: I am just repairing for a friend a HEATH =
SB1000 and=20
on 160 the switch contacts that connects the C26 270 pF =
doorknob=20
are both burned. It seems that the switch could not take the current =
through=20
this condenser? Is this a often found problem in this amplifier? =
Where do I=20
find a new switch ? I am planning to let the new switch contacts =
actuate a=20
small high frequency relay that handles this hf current??</DIV>
<DIV> </DIV>
<DIV>This is an extremely common problem. It is a high voltage =
problem, not=20
current.</DIV>
<DIV>You can probably get a switch from Ameritron. I bought several =
from=20
Heath before</DIV>
<DIV>they went out of the ham business. Years ago, they were $118 =
each! Also=20
Ameritron</DIV>
<DIV>has mica replacement caps. for the doorknobs in the tank =
circuit. This=20
is another big</DIV>
<DIV>problem in the SB-1000. It has always been my theory that there =
is a=20
Tesla coil</DIV>
<DIV>effect in the tank circuit. The switch probably did not burn =
out when=20
the amp was</DIV>
<DIV>operating on 160m, but on 80m...just a guess based on my =
experience=20
with the</DIV>
<DIV>SB-1000. Heath tried to minimize the failure rate on the band =
switch by=20
having</DIV>
<DIV>the builder solder flat washers on certain contacts. Those that =
did not=20
do that</DIV>
<DIV>lost their switches almost immediately, so that shows that the =
switch=20
was not</DIV>
<DIV>a good choice for that particular layout.</DIV>
<DIV><BR>The toroid on 160 is red not yellow, by the way. Any=20
comments?</DIV>
<DIV> </DIV>
<DIV>Red is a very good choice for an L coil for 160 and 80m. It =
takes=20
fewer</DIV>
<DIV>turns of wire to get the desired inductance. I use the big red =
ones=20
in</DIV>
<DIV>a couple of 8877 amps.</DIV>
<DIV> </DIV>
<DIV>GL!</DIV>
<DIV>Phil, K5PC<BR></DIV></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>
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