I have an Ameritron AL-80B on my desk that I drive with my Omni VII. It
does not have a dedicated HV or FIL switch. When the amp is switched ON, it
brings up, with delay, the filament voltage and the high voltage along with
the cooling fan.
I would first check between the tube elements with an ohm meter. You should
see a very low R value across the filament pins which are the 2 closest
together. There are 3 grid pins, all common, and measuring between each of
them you should find a very low resistance. There must be NO resistance
between the filament and grid pins and NO resistance between the grid pins
and plate connector on top. If this checks out OK then proceed as follows.
If you find resistance between any of the elements, grid to filament, or
grid to plate, then you have a suitable lamp base. Do not put the tube in
the amp.
First we must presume the amp is working correctly with the present tube. If
so, then unplug the amp and remove the covers. Remove the existing tube and
install the new tube. Be sure the amp has the correct fuses installed. Put
the cover back on the amp and secure to engage the safety interlock . Plug
in the amp and turn it on. There is no need to "burn in" this type of
tube. If there is an issue with the tube, it will immediately be obvious.
You may see a bit of a blue glow inside the envelope but this will go away
with use.
The with the transceiver and a dummy load start with about 20 watts of drive
and tune for maximum output. Then increase drive to about 80 watts and
touch up the tuning and loading for maximum output. Do not allow the tube
to exceed 200 ma of grid current nor 525 ma of plate current. With key down
and about 80 watts of drive one should see 1000 to 1200 watts output
depending on band. A power output of less than 1000 watts with 80 watts of
drive indicates a tube that is "soft" or does not have proper emission.
Having the filaments on and no HV serves no purpose. With drive and proper
tuning the plate will show color. The red glow of the tube plate will
consume any air that has accumulated into the tube envelope.
73
Bob, K4TAX
----- Original Message -----
From: "Rodney" <w3krq@dejazzd.com>
To: <wb5jnc@centurytel.net>; "Discussion of Ten-Tec Equipment"
<tentec@contesting.com>
Sent: Sunday, August 03, 2014 8:10 PM
Subject: Re: [TenTec] OT: Need advice checking out a stored 3-500
put it in your amp only turn on the filament and let it run for 5 or 6
hours until you turn on plate voltage. I know a ham that had 34 304tl
tubes and that what he did.
y
-----Original Message-----
From: Al Gulseth
Sent: Sunday, August 03, 2014 8:41 PM
To: TenTec@contesting.com
Subject: [TenTec] OT: Need advice checking out a stored 3-500
(Posting this for a local fellow ham who currently isn't on the web)
As the subject line says, a local ham friend of mine asked me today about
how
to go about checking out/waking up a 3-500 (Z?) that came as a spare with
his
AL-80A when he bought it a few years back. He's not really sure how long
the
tube had been sitting around unused/un-exercised before he bought the amp.
I've seen conflicting info on how to go about it, and the last time I had
my
hands on something like that was 30+ years ago when I worked in the
broadcast
industry before I switched to a different career. Any suggestions? Other
than
his amp I don't have any way that I know of to check it.
Contact me off list if appropriate.
BTW Ten-Tec connection: he's driving it with an Orion.
TNX/73, Al
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|