[TMC] TMC-SBT-1KB

[Roy Morgan]

On Jul 2, 2008, at 2:21 AM, H.L. wrote:
> http://jptronics.org/radios/TMC/manuals/
>
> It includes a complete manual for the SBE-2. I, too, have a SBE-2  
> without power supply. Its pin connections and voltages are as follows:
> Pin J: +225VDC B4...
> I think the power transformer HV is 350-0-350 VAC.

Pardon me if my memory here is not quite right - I did not dig up the  
tech manuals on these things:

Not really. The "high" voltage in the B+ transformer is quite low,  
actually.  That's the trouble, along with the double 115 volt primary,  
I had in finding a suitable replacement for a GPT-750 with an SBE  
mounted in it.

> The current must be at least 300 ma because of the 6146 output tube  
> in this 20-tube 1-Watt exciter.

Probably not that high. I am sure the 6146 is run in class A mode at  
very moderate current.  If I remember right, the rectifier tube is a  
5R4, but it's current rating is nowhere near approached.  However,  
there are a lot of smaller tubes in the SBE, and together their plate  
current needs may add up to more than I'd guess.

The goal is high linearity, not output power. The thing will deliver  
only a couple of watts max.  (If you measure this, note that the  
output is meant for 72/75 ohm impedance level.)  Most of the equipment  
driven by the SBE and similar exciters would develop full power with  
200 milliwatts of drive.

The Northern Radio similar equipment used a 2E26, the junior version  
of the 6146.

Roy


Roy Morgan
k1lky at earthlink.net
Lovettsville, VA 20180