SB-200 Standby switch

To start with, this really is not necessary, but if you are like me you have to wonder how much component life is used up every time the SB-200 goes through a power on/off cycle. The 572B tubes are, for all intents, instant on and let you apply 1200 watts PEP at will. However, each time the amp is powered up with cold tube filaments and discharged filter caps, significant stresses are placed on the transformer and the power supply components. Turning the amp on and off many times during an operating session, to comply with the FCC rules of minimum power to get the job done, seems unduly stressful.

Here is my solution to the problem without drilling holes in the cabinet of the SB-200.

First, take a trip down to the local Radio Shack and purchase a new Pot and switch to replace the "Rel Pwr. / SWR Set" control. 100K pot (271-092) switch (271-1740)

Remove the original pot and replace with the new pot/switch combo. You'll have to remove the cover on the new pot to install the switch and cut the shaft of the new pot down to length.

Wire the switch in series with the "Ant relay" ckt.

Replace the covers after checking your soldering and wire dress.

Throw the power switch and make sure no smoke leaks out!

Now, with the "Rel Pwr/ SWR Set" control fully counterclockwise, the amp will be in standby mode.

Rotate the control clockwise and the amp is online - rotate further to set the meter for full scale.

Done!

No holes!

Maintains original looks!

Saves stress on components!

Allows you to comply with FCC rules!

Cost - $2.30 + tax and your time!

Enjoy

Rodger

N4NRW