[Amps] re: EBS at soft or quiet moments

[2]

>Are EBS circuits worthwhile..? 
>-
>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. 
>- 
>The last Alpha EBS circuit I tested, required less than 
>a watt to activate ("trigger"). 
>-
>(The standby/receive mode of a standard amplifier 
>most often cuts off the cathode current, as does 
>the EBS type circuit )
>-
>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...?
>-
**  That there is no reason to  switch to not-linear bias during a spoken 
word.  I can spot RF-actuated EBS on the air by the rough sound and 
increased splatter.  
-  There is no reason to ever switch the amplifier out of linear-bias 
when the transceiver is in Tx mode.
>- 
>From: 2 <2 at 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 at somis.org
>
>
>
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Rich, AG6K, 805-386-3734, www.somis.org / new e-mail adr r at somis.org