Upgrading my Heathkit SB-221 with Harbach upgrade kits

Finally, after I have got all the upgrade kits that I ordered from Harbach, I started putting them together today. It took me many hours since I couldn't visualised on how they're supposed to be installed based on the installation guides which really useful nonetheless.

I started my upgrade with the RM-220 meter board. It has missing R2 resistor and Jeff had shipped it along with my FB-220 kit which I ordered later. I didn't think it was necessary to upgrade the capacitors bank but many of my friends suggested it since the amplifier was built 30+ years ago. The capacitors might have dried up. Along with RM-220, I did the FB-220 upgrade too since  I need to work on the connection anyway. Anyway, the meter board doesn't require the old zener diode, so I've removed it as per the installation guide.

After the two upgrades, I did a test run just to make sure everything was okay before going for the other upgrades. The HV reading seems to be a okay and as per the original specs. Before the upgrade, the reading were a bit off for both CW and SSB mode.

Satisfied with the HV side upgrades, I went ahead with adding the SS-221-240 upgrade. This requires a lot of works since there are four things need to be done:

1. Installing the circuit board (it is upside down since I couldn't find a safest way of installing it and looking at some of the photos found on the net, they're doing the same thing.
2. Installing the bridge rectifier.
3. Adding  transient voltage suppressors ( 390V ZNR suppressors).
4. And lastly the diodes across the T/R relay.

The last part before doing another test run was to put in the SK-220 soft key. Its a bit cramp there since there is RF choke installed. The installation guide doesn't warn this though. But I managed to squeezed it in.

Done with all the upgrades, I did a check on all connections and tidy some of the wires with cable tie. I did a power up test run and let it ran for half an hour to see if I any smoke came out and everything went just fine. Put back the casing and now ready for RF test. This will be done when I get my hexbeam fine tuned. Stay tune!