[Milsurplus] TBW modulation

[howard holden]

Jim, you can do well with lower final plate V, but the 500 or so for the 
screens and 837 osc/buffer should be near what they specify. We run the TBW 
on the Ling with 1300V, and i run my GO-9 with 1000V on the plate of the 
803. We get 80W on 80/40 with the TBW, and I get 65W with my GO-9. Of more 
importance than the final voltage is the condition of the 837s. You need to 
swap out a few tubes to find the best combo for the osc and buffer. You can 
use 1625s in there if you open the side of the base and detach the 
suppressor and make it a separate connection to the appropriate pin.

As far as modulation why would you want to NBFM it???

We haven't tried the suppressor grid mod, as we don't have the 843 tube, and 
it's a rare bird. Same basing as a 37, but higher voltage etc. There are no 
direct substitutes.

I believe I sent you a schematic for the TBW already? Totally different 
connection schgeme on the GO-9 vs the TBW. Easy to make connections through 
the bottom connectors, using female "bullet" crimp receptacles. If you need 
the schematic again let me know.

Howie WB2AWQ/NX2ND


>From: "Falls, Jim" <Jim.Falls at conservation.ca.gov>
>To: <Milsurplus at mailman.qth.net>
>Subject: [Milsurplus] TBW modulation
>Date: Tue, 30 Oct 2007 10:56:19 -0700
>
>The TBW/GO-9 thread jogged my memory.
>
>
>
>I have a tubeless TBW-4 in which I am re-winding the main roller
>inductors (someone stripped off the "silver" wire in the ancient past).
>Other than that, it's intact AFIK. Assuming I can build the PSU shown in
>the Volume 2 Beach book of 1948 without killing myself, how do I hook it
>up? The numbering system on the Beach PSU specifically says GO-9, not
>TBW. Has anyone done the hook-up for the TBW? Homey don' wanna mess with
>2 kilovolts DC.
>
>
>
>Can one get decent results with lower B+ on the finals? The Beach PSU
>puts out ~10x the voltage I'm used to working with and am VERY
>leery..........
>
>
>
>And now, the meat of the problem: Beach also shows a NBFM modulator one
>can build to drive the TBW output, but (at least to my eyes) does not
>specify precisely where to hook it up on the accompanying schematic. On
>my TCS, this an entire circuit that is switched in and out. The TBW
>schematic in the book looks like I would bring it in just as if I had
>the rectifier/modulator unit in place. Sound reasonable?
>
>
>
>Jim Falls
>
>KG6FWT
>
>Eureka, CA
>
>
>


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