{Collins} Re: 30L-1, ALC and modern radios question

[dgsvetan@xxxxxxxxxxxxxxxxxxx]

Glan and All,

To that I can only add "... and so can a monitor scope."  Glen, your point 
is well taken about use of a spectrum analyzer with transmitters, 
especially when using amplifiers.  While I am among the few witrh a 
spectrum analyzer, I can tell you that I use it only when checking out a 
rig and/or amplifier in the shop for things like spurs and excessive 
harmonic output.  I would not care to watch a spec an during actual QSOs. 

I have my trusty SB-610 monitor scopes and would not want to be without 
them.  I can immediately see if the peaks of my voice signal are being 
clipped or otherwise mutilated.  I still contend that HF would be a much 
cleaner environment if more hams used monitor scopes when running amps or 
those speech compressors.  I think some guys would be amazed at horrible 
they sound when running incorrectly adjusted PAs or compressors.

For those who don't know, a monitor scope is really nothing more than a 
basic oscilloscope that has been expecially configured for easy 
installation into the coax feed line and includes the necessary 
attenuators to compensate for different transmit power levels.  With 
suitable sweep circuits, the monitor scope applies RF to the vertical axis 
and voice frequency sweep rates to the horizontal axis.  The result is a 
real time picture of your transmitted waveform that does not have not have 
the problem of slow meters following your voice.  Again, a lot of poeple 
would be amazed at how much they could reduce their mic gain and NOT drop 
peak output power at all.  When the peaks of your voice hit the same 
ampltude as did your CW carrier in tune-up, you are at max output power. 
Period.  You will never see that with a mechanical meter. 

If this discussion has caught your interest, see Heathkit, Yaesu, or 
Kenwood for monitor scopes.  Or, see H-P/Agilent or Tektronix for spectrum 
analyzers or regular oscilloscopes.  BUY ONE of something, then use it. 
The rest of us will be glad you did. 

73, Dale
WA9ENA

 



Glen Zook <gzook@xxxxxxxxx> 
Sent by: collins-bounce@xxxxxxxxxxxxxxxxxxxxx
03/25/2008 02:34 PM
Please respond to
gzook@xxxxxxxxx


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Subject
{Collins} Re: 30L-1, ALC and modern radios question






An oscilloscope can help.  However, just an
oscilloscope will not actually show all distortion. 
Now using a spectrum analyzer will show a lot more. 
But, the vast majority of amateur radio operators do
not have access to a spectrum analyzer.

Glen, K9STH


--- cemilton@xxxxxxx wrote:

How about adding an O'scope to the lineup?? Gives a
pretty good picture of what's coming out of the
amplifier.









Glen, K9STH

Website:  http://k9sth.com


 
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