[Boatanchors] Which 6146 in AF-67?

[Glen Zook]

Be careful using the 6146B/8298A or the 6146W tubes in the AF-67.  Those versions are much harder to neutralize in equipment designed for the 6146 or 6146A/8298.  Many of the older transmitters are very unhappy with the 6146B/8298 or 6146W tubes.
I have run into like 3-different transmitters, of exactly the same model, with serial numbers very close, in which 1 of the transmitters had no problems, at all, with the 6146B/8298A and the other 2 had all sorts of problems.
The 6293 is an excellent replacement for the transmitters designed for using the earlier versions.  It basically is a 6146A/8298 with a heavier plate.  That tube was used as a pulse modulator with inputs up to 1000-watts!  When run under the same operating conditions as the 6146 or 6146A/8298, the 6293 generally lasts between 5-times, and 10-times, more length of time than the other tubes. Glen, K9STH

Website: http://k9sth.net
      From: "qrv at kd4e.com" <qrv at kd4e.com>
 To: BOATANCHORS <Boatanchors at puck.nether.net>; Florida boatanchors <FLBOATANCHORS at yahoogroups.com> 
 Sent: Friday, December 12, 2014 12:34 PM
 Subject: [Boatanchors] Which 6146 in AF-67?
   
Which version of the 6146-series will provide the most
reliable & stable service in an AF-67, please?

Does the tube selected matter if operating variable-carrier
DSB (a modification to provide SSB-friendly and AM output)
or as-designed plate-modulated AM?