[Kenwood] Service for TL-922A

Sat Apr 23 16:11:16 EDT 2011

On 23 Apr 2011 at 12:40, Donald Sanders wrote:
> Like the slow start mod for the SB200 is not really necessary as
> the transformer was designed by Heath engineers with enough impedance
> to provide protection. However with the slow start I do not see the
> lights dim at turn on and the transformer does not hum. So I am
> pleased with that mod.

I agree. With MY SB-200s (I have two) I plan to implement a slow-start mod 
of one kind or another as soon as I can. Although it is not needed (IMHO) to 
protect the equipment, I don't like the momentary dimming of the lights, and 
believe that reducing any momentary load is simply a good idea.
This is especially true if one increases the values of the power supply filter 
caps in order to improve dynamic regulation.
For instance, my most-used SB-200 noew has 470 uFd caps in place of the 
original 125 uFd caps, all of which had changed to much lower values since 
it was built. I think the best one I had was down to 70 uFd.
Dynamic regulation is noticeably improved, as proven by a 'scope 
examination. This reduces some slight spurious emissions on SSB.
Measures sells 560 uFd caps for the same use in SB-220s and TL-922s.
Ken W7EKB