[ICOM] IC-746PRO with Ameritron Amps

[Van van Bergen]

I have the same "Sometimes" delay with my 746Pro. did the same with my 
Kenwood TL922A amp and now with my AL811H amp. It was a lot worse with the 
TL922A than with the AL811H. The relay in the AL811H is a lot faster than 
the TL922A amp was. Maybe someone can come up with a solution.

73
Van
WD6FGB

----- Original Message ----- 
From: "Alan Zack" <k7acz at cox.net>
To: "IC746 Group" <IC746 at yahoogroups.com>; "IC746/7400 Group" 
<ic746_7400 at yahoogroups.com>; "Icom List" <icom at mailman.qth.net>
Cc: <mfjcustserv at mfjenterprises.com>; <ameritron_equipment at yahoogroups.com>; 
<n4dek at triad.rr.com>; <fsense at copper.net>; <ameritron at ameritron.com>
Sent: Sunday, January 23, 2005 7:16 PM
Subject: [ICOM] IC-746PRO with Ameritron Amps


Several of us with Ameritron Amps have been experiencing keyup
problems when using IC-746PRO's.
I tried searching the archives on the 3 IC-746 related lists but could
  not find any info on this problem.

Here is the situation:
IC-746 and Ameritron Amp combo works fine on AM, FM, CW, and RTTY.
On SSB there is SOMETIMES, not always, a slight delay to see power out
when keying.  For example, my call is K7ACZ.  I can push the PTT on my
mic, say K7ACZ but only the ACZ gets transmitted.  The amp relay
clicks in fine with the PTT being pressed but does not show power out
until after a slight delay.
Looking at the IC-746's meter when this happens I observe the Po not
showing power out on my first word or so, the SWR is at minimum and
the ALC goes full scale, past the normal range.  After a short delay
everything is normal.
Operating conditions:
1.  Does this regardless if the ALC line is connected between the 746
and amp or not.
2.  Does it at all power levels of the 746.  Have tried from 10 watts
to 100 watts, no difference.
3.  Does it on all bands.
4.  Does it regardless if the 746PRO auto tune is on or off.
5.  Hitting the 746PRO TUNER button (to force the 746 to tune to the
amp's input circuits) does not help.
6.  Tried doing a steady AHHHHHHHHHHHHHHHHHHHHHH into a dummy load,
hitting the PTT on and off, and watching sometimes full power as soon
as the PTT is pressed and other times a slight delay.  Each time there
is a delay the 746PRO meter shows no Po and max ALC for a second.
7.  As expected, VOX cannot be used as each time VOX drops out and
then kicks back on you may or may not be putting power out.

Have tried different coaxes, went direct into a dummy load, different
antennas, no change.

Keying circuit is a direct connection from 746PRO's SEND jack to Amp's
RELAY jack, no buffers or extra keying circuits.  Ameritron says their
amps will not damage the 746PRO's keying circuits by using a back
pulse canceling diode in the AL-80B I have.

Has anyone else experienced this?  On the Ameritron Amp reflector it
seems only a few of us see this, and only with the 746PRO.

I have just purchased this amp Friday from AES and am ready to return
it if I can't figure out this keyup problem.  I am a contester and
want to use my VOX, which I can't do with this amp.

TIA & 73
-- 
__________________________________________________________________________

Alan Zack
Amateur Radio Station K7ACZ
Las Vegas, Nevada, USA
Quality Engineer, The Boeing Company, Retired
Aviation Chief Warrant Officer, U.S. Coast Guard, Retired
U.S. Coast Guard, Always Ready, Always There
Every hour, Every day, Around the Clock and Around the World
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http://www.gocoastguard.com
http://www.uscg.mil/d14/units/asbp/uscgasbp/
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