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!

Digital Voice Mode - In Malaysia

As of now (early 2018), the digital voice mode is still in the infant stage in Malaysia. The interest from local hams seems to be slow and this probably due to many reasons. Anyway, I've blogged this in the myaprs.my blog, so I will not repeat it here. Here is the link if you would like to read more:

http://www.myaprs.my/2017/11/going-to-new-chapter-digital-voice.html

Anyway, for those who're looking into how you would be able to make a contact with local hams in digital voice mode, the following information might be useful:

• Yaesu Fusion - Wires-X
• MALAYSIA-NET room
• 9M2RKL (Klang Valley) - 439.600 MHz, Shift -5 MHz
• 9M4RMU (Melaka) - 439.8250 MHz, Shift -5 MHz
• Yaesu Fusion - YSF Network
• MY Malaysia Net reflector
• DMR - BrandMiester Network
• Talkgroup 50210 

The three networks above are bridged, so you can either access it using hotspot from BrandMiester or from YSF Network depending on what radio you have. For Wires-X, you need to either access it from any repeaters that are already connected to Wires-X, or from any Wires-X nodes/gateways too.

Got myself an SB-221!

I've been aiming to own one since I upgraded my license back in 2012 and I'm more interested on the old tube amplifier like those from HeathKit, Kenwood and Yaesu. The only thing that holding me back was the cost to get it shipped from US to Malaysia. The SB-200 and the likes can be had for around USD$400-600 but the shipping and handling can be costly due to the weight and customs charges, it might comes to a total of USD$200 for shipping cost.

My luck changed, on 24/12, I was browsing mudah website and was looking for something unrelated but was bumped to an advert, a Heathkit SB-221 for sale. The advert was posted about a month before that and according to the guy, there was no other enquiry other than from a person from neighbouring country. So, the deal went through and on 27/12, I got a very clean (from outside) and very good condition SB-221 with a 10M mod done. No other mods have been done since the amplifier was built and according to the OM, he hasn't turn it on for the last 10 years since he made a move to Malaysia.

Since I don't have a proper radio to test everything, I did only a turn-on test and let it run for half an hour. No burning smell, and the tubes glowed as expected. The only I did was to replace the broken 240V cheap plug with a much better one. The plate voltages for both CW and SSB are a bit shy to the one on the specs, probably due to the age but well within the 10% tolerance.

Anyway, before I get this connected to my current rig, a TS-590SG, I've ordered few upgrade kits from Harbach Electronics which include the soft-key, soft-start, meter board and the capacitors block.

Some photos when I took off the casing: