Heathkit SB-200 amp

[StoppieSnob]

My dad's been working on this old Heathkit SB-200 amp he snagged on eBay, and really getting it dialled in.

He's already dropped in a bunch of new stuff from Harbach, and he swapped out the other old caps in there too. His next move is to change the RCA input jack over to a BNC.

He powered up the amp (not hooked up to a radio yet!) and everything looks good, no sparks, no sizzling, no weird smells.

I want to help him a little with this, so is there any specific mods for the ALC to get this amp to play nice with his IC-718 needed? Or should he be all set and ready to go once he changes that RF input jack?

Any insights would be a huge help for him!

 

[Efficient-Remove864]

He's doing a great job fixing up that old SB-200 and making it work again!

For the IC-718, adding a simple ALC limiter or buffer circuit can help smooth the integration and avoid overdriving the amp. Some use a series resistor with the ALC line, start around 10k and tweak from there. Once that RF input jack is sorted, it should be pretty close to plug-and-play.

 

[Altinababy]

Most modern radios like IC-718 play nicely with the stock setup once the amp is properly biased and all caps and tubes are in good shape. Swapping the RCA for a BNC won't affect ALC behavior but make sure the ALC line from the IC-718 is connected correctly and maybe start with a low drive signal to watch how it responds

 

[Skimmy]

Sounds like he's done a solid job so far...before hooking it up to the IC‑718, have you checked whether the ALC circuit needs adjustment to match the rig's output, or will it handle it automatically?