[Amps] Requesting opinions on a Drake L-4b's tubes

[Donald Fox]

 Larry:
Congrats on adding the L4B to your shack. I have owned both the L4 as well as the L4B. It sounds like the tubes in the amp are soft. You should see 600-700 watts out with 80 or more watts in for the CW position, and well over a KW out in SSB setting. For the most part, a 3-500 is a 3-500, so if you want/need to run models that don't "match", it's not a huge dea

I might be wrong, but I'm pretty sure the 3-500's are in parallel, not PP. There are some mods you can do to help the power supply run much cooler, and also to extend the life of the on/off switch to name a few.
They are built like a tank, and for the power limits of their era, do a very respectable job.

Don N8ECH
     On Friday, December 23, 2022, 03:48:42 PM EST, A Lawrence Fibich <lfibich at sbcglobal.net> wrote:  
 
 I just acquired this Drake L-4b as the third owner and no nothing about its history. It puts out 400 watts with recommended Plate and grid currents (.56 amps, and 225Ma respectively). If overdriven (.8 amps; 100ma) it will do 600 watts. At 'idle/resting' should be 0's but shows .1 plate amps & 75 ma grid current- which I think shows a tube problem.
Now my request for an opinion, what do you suggest:  
1. I got 2 unopened tube boxes from Drake - thinking to simply replace/use them and see what happens.
2. Surprise - 1 is the 3-500G- (Graphite plate) - the other turns out to be a 3-500Z (old style) . 3. The unit has 2 (original/old) - 3-500Z's in it and really no way to test them4.  So? what to do?5. Live with it, and leave the 2 in the unit and live with 400 watts and? or- maybe overdrive them and go for 600 watts? ? how long do you think they would last?6. Use the 'new' 3-500Z with one of the 'old' 3-500Z's?7. Use the 'new' 3-500G (graphite) with the 'new' 3-500Z?8. Use the 'new' 3-500Z with one of the 'original/old' 3-500Z? 
Of course, the finals in the Amp are push pull configuration -2k PEP & 1K CW input watts. 
Thanks for ALL your suggestions/recommendations.  73Larry F.W6EF
_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps