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Old January 21st 11, 10:16 AM posted to rec.radio.amateur.antenna
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Default ESD Protection ?

On Jan 8, 9:08 pm, KD7HB wrote:
Does the radio have any coils in the front end? Like the old-time radios, a primary coil between the antenna and chassis ground. If it has coils, there is NO way for static electricity to build up beyond millivolts, since all is at DC ground.


Paul, KD7HB


Andy adds:

Another way to accomplish the coil isolation would be to use a
1:1
50 ohm wideband transformer from Mini-Ckts lab. They are only a
couple dollars...
If you have a good parts box, you can wind one yourself as they are
very simple. The ARRL handbook can give you guidance if you are
not familiar with the technique. Simply a bifilar winding around a
small ferrite toroid.....

I'd also still use a couple of backtoback diodes, in parallel with
a
neon lamp. Couldn't hurt........ might help, once.......

Andy W4OAH

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Old January 21st 11, 07:34 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Mar 2007
Posts: 801
Default ESD Protection ?

AndyS wrote:
On Jan 8, 9:08 pm, KD7HB wrote:
Does the radio have any coils in the front end? Like the old-time radios, a primary coil between the antenna and chassis ground. If it has coils, there is NO way for static electricity to build up beyond millivolts, since all is at DC ground.


Paul, KD7HB


Andy adds:

Another way to accomplish the coil isolation would be to use a
1:1
50 ohm wideband transformer from Mini-Ckts lab. They are only a
couple dollars...
If you have a good parts box, you can wind one yourself as they are
very simple. The ARRL handbook can give you guidance if you are
not familiar with the technique. Simply a bifilar winding around a
small ferrite toroid.....

I'd also still use a couple of backtoback diodes, in parallel with
a
neon lamp. Couldn't hurt........ might help, once.......

Andy W4OAH



Back to back diodes will cause a problem if you have strong signals in
the area (enough to get the diodes to start to conduct) from intermod.

Neon lamp fires at 60-70 volts.. hopefully whatever is downstream can
tolerate that.

It's a classic problem.. all the things that protect the front end also
degrade the performance in one way or another. You have to make the
decision about whether you want best performance and highest risk or
vice versa.
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