Are EBS circuits worthwhile..?
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I would venture to say there is little time where a
radio driving an amplifier (combination) has no
RF output in the transmit mode. Even quiet station
transceivers have a minimal amount of RF output
result from ambient room noise.
-
Add some compression and the story gets
worse.
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The last Alpha EBS circuit I tested, required less than
a watt to activate ("trigger").
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(The standby/receive mode of a standard amplifier
most often cuts off the cathode current, as does
the EBS type circuit )
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As quiet as I can be, my peak reading watt meter
and scope often indicate some RF output most
of the time... even between words on breath and
room noise. Is the EBS honestly helping much
in linear mode operation when the input rarely
falls below the control detector threshold in a
typical amateur operation?
-
I can see the case for CW operation, but
most SSB operators are going to bias on
during most any portion of the transmit
mode where the EBS is supposed to
pay off..?
-
What might I be overlooking...?
-
skipp
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From: 2 <2@vc.net>
*** With no input RF, there is always zero RF circulating current, no
matter what type of bias switch is used.
-- . When SSB RF drive drops below the EB-switch threshold level
during soft-syllables, the amplifier switches in and out of non-linear
bias. This results in more IMD during soft-syllables. Another problem
with RF-actuated bias switching is that there is no headstart for the
amplifier's RF relay contacts to close before RF arrives. This results
in hot-switching the RF input relay and the RF output relay in the
amplifier. For AM and FM modes, RF-actuated bias switching does not
switch during soft-syllables, so there is no added IMD, although the
hot-switching problem still exists.
>
>Thanks!
>
> ***dan, K6IF
Rich, AG6K, 805-386-3734, www.somis.org / new e-mail adr r@somis.org
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