[1000mp] Driving 3-500Z Amp with Mark V

Tue, 4 May 2004 14:59:15 -0400 (GMT-04:00)

Assuming that you have the amplifiers switching from standby to transmit correctly (and there are two different ways to switch the amp), place the Mark V in CW, with the amplifier off, and with the auto tuner off, set the power output to about 30 watts while sending a string of DITS at about 30 words per minute.

You may see a higher swr on the Mark V meter, as you tune through the bypass circuit of the linear into your antenna system.

Then, with power adjusted, turn on your linear, with low voltage on the plates (CW Tune Mode), and quickly peak both the loading and the tuning controls for maximum output.  Your Mark V should still show about 30 watts on the output meter, while you are sending the DITS in CW, while loading the amplifier.  This CW tune up method reduces the strain on the power supply and the tubes.

If you now show several hundred watts output, your amplifier should load the rest of the way, to a maximum of about 1,500 watts, (after changing to high voltage) for something like 80 to 100 watts of drive, for a good pair of 3-500 ZGs.  The triodes should load easily, and quickly once you change over to high voltage for SSB.

In general, it should not be necessary to use the tuner for driving your linear, meaning the linear's  input impedance is close enough to 50 ohms to work well with the Mark V.

I like to use a good PEP meter on the output of the linear, which helps to quickly peak the loading and tuning capacitors, and shorten the tune up time.  The Autek WM-1 works well, and is accurate also.

Good luck.

73,

Mike Schatzberg
WB2AJI

-----Original Message-----
From: frank60 <[email protected]>
Sent: May 4, 2004 11:57 AM
To: [email protected]
Subject: [1000mp] Driving 3-500Z Amp with Mark V

I have a brand new Mark V and I am trying to drive
a Drake L7 amp and a TL-922A amp but the Mark V
just shuts down and wont put any power out at all.   

I've been driving these two amps with all my other previous
rigs including the Yaesu 920 with no problems.   
I even put both amps into a 2000 watt dummy load and it
still wont drive them.     It just drops down to zero output
power and shuts completely down as I try to drive either 
amp.  

My station grounding is via a large copper plate that is used
as common ground going to a large grounding grid outdoors.  

So this appears to be a problem only related to the Mark V.

Has anyone else had a similar problem? 

[email protected]    

_______________________________________________
List Moderator: Richard Lubash N1VXW
1000mp mailing list
[email protected]
To Change Options or Unsubscribe:
http://mailman.qth.net/mailman/listinfo/1000mp