Many transmitters were built with out parasitic suppressors during WWII using
813. I believe it is because the gain drops quickly above 30MHz and there is
less of an opportunity for the tube to oscillate at VHF frequencies. Most glass
"modern" glass power grid tubes are at least good for full output up to
110 MHz so that they can be used in FM broadcast transmitters.
73
Bill wa4lav
________________________________________
From: amps-bounces@contesting.com [amps-bounces@contesting.com] On Behalf Of
Jim Thomson [Jim.thom@telus.net]
Sent: Monday, April 12, 2010 6:35 AM
To: amps@contesting.com
Subject: [Amps] 813's.. Parasitic suppressor's
Somebody asked a while back abt the need for parasitic suppressors' on a GG-
813 amp. A buddy
had one blow up on his 2 x 813 amp last yr.. across town. he tossed both the
blown one.. and also
the remaining one. Amp runs just fine with NO suppressors. Another fellow
runs a 4 x 813 amp,
again with no suppressors. The tubes all balance out too..equal glow. I'd
try it with it with no suppressors
1st.... then if you do have stability problems.. then add them.
If the screen and control grids are well grnded [via strap] to chassis... you
won't have stability problems.
I have had 813's with as high as 3 kv on em, no load... yrs ago, with no
stability problems, but that amp
did have suppressors in it [2 x 813's in GG] [80-10m]. That was back in
1975. It's a pretty stable tube.
Later... Jim VE7RF
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|