[AMRadio] Was what is this???? now why i like am

[James M. Walker]

Howdy folks,
Keeping in mind that all amplifiers are NOT the same operationally, I use a 
refurbished
system, sometimes for AM/CW/RTTY operation. It is a commercial unit made by 
the
no longer in operation Scientific Radio Systems company. The model is the 
SR-120
System 100 watt exciter Channelized, and A pair of 3-500Zs in the pa 
section. My
carrier level with out modulation is right around 300 watts with voice peaks 
taking it
to 350-400 watts measured with Bird wattmeter. As usual your mileage may 
vary,
I get good signal reports and "NO HASSLES" from the nearby SSB crowds.
Rig can be seen at http://eshop1.chem.buffalo.edu/SR-120.html

It is still working fine, but antenna rules limit my operation to nights 
only, even
with the preponderance of Cable now! Front end overload is a hassle even on
SSB, and CW drives them crazy cause all they hear is pops at 45 WPM
Jim
WB2FCN/WD2XSH-22


----- Original Message ----- 
From: "Rob Atkinson" <ranchorobbo at gmail.com>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Wednesday, December 01, 2010 7:57 AM
Subject: Re: [AMRadio] Was what is this???? now why i like am


Jay, maybe because I got up 15 minutes ago but I don't know what you
mean.  I have a FT1000MP and there is a "power" pot on the front panel
which I think somehow adjusts PA collector current and as far as I
know, that's it.  What's the carrier control?  Maybe a control found
on older JA rigs with tube PAs?

Jim in Waco, what is your exciter and amp?  I use the exciter to drive
a pair of 3-500zgs.  they are g.g. cathode driven so they need more
drive.  There are limits due to plate dissipation and B+ (2800 v.) but
20 w. drive gets 300 w. out, which is about my maximum for my amp.
the ricebox has a 200 w. PA so 20 w. modulated does not get any ALC
reduction.  If your exciter is 100 w. maximum you probably want to
stay at around 12 w. if you make long transmissions.  at 20 w. the
heat sink on my rig gets pretty warm after a while--the 200 w. spec is
for SSB.
I use a SB610 monitor scope and an old Tek 438.  These old scopes are
cheap at hamfests--actually the 610 cost more than the real
oscilloscopes hi hi.  You can turn a scope into a trapezoid monitor.
I'm sure we all can tell you how to do it if you want to know.   if
you get an old heath monitor scope replace the caps in the h.v. CRT
supply.

73

rob
K5UJ


On Wed, Dec 1, 2010 at 3:53 AM, Jay Bromley <jayw5jay at cox.net> wrote:
> You will get better performance using the carrier control for adjusting
> power. Leave the power control wide open so when you modulate you will 
> have
> plenty headroom.
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