The outside of the case and face plate looked clean and very well taken care of, no dents, major scratches or extra holes added. The controls worked albeit some were a bit tight. But the best part, all the original knobs are intact!
I was almost scared to open the case, you never know what you might find...

Heathkit SB-101 What's in there?
Maybe WHO was once in there would be a better question. Opening old radios that have been sitting for a long time often leads to many surprises, they become home to all kinds of critters. I was happy to find the only long term residents in here were a few spiders and they have moved on.
The addition of the speaker was a nice surprise and was done very nicely.

Heathkit SB-101 Dust and Cobwebs meet Mr. Air Compressor!
I'm very blessed that most of the dirt inside was dust and cobwebs. The air compressor did a great job of getting rid of this.
I was very excited to see just how clean the radio is after all these years.

Under the chassis is amazingly clean, and appears to be a factory build, or done by a very exceptional builder.

Inside the RF cage doesn't show signs of excessive overheating, this is awesome!

Heathkit SB-101 Rub-A-Dub Dub Time.
After cleaning the dust and cobwebs from the inside of the radio, I've turned my attention to cleaning the dirt and grime off the circuit boards. This is a must because both are conductive and can cause major problems when power is first applied. This process will require a few days of work and a large box of Q-Tips!
I'm using mostly plain water and in some areas Dawn dish washing soap. Be careful of cleaners because they can remove printing on the circuit boards.

Here is an area after some cleaning with soap. I'm not doing a restoration on this radio so I'm not trying for a factory fresh look. My object is to clean up the boards removing the dirt to ensure proper operation while still looking good, this is a refurbish. A complete restoration is a major undertaking.

After the cleaning I'll do an overall inspection of the wiring looking for any mods or broken wires or parts. Next will be to take a sampling of the resistors checking their values against the schematic. All electrolytic caps will be replaced, and the belts for the tuning caps will be replaced. From there I'll add power to it and see what happens. Stayed tuned!

Aug 20, 2024
I had some time today so I finished cleaning the circuit boards and face plate. It turned out pretty well, there's a couple of spots that I'm sure I missed but I'll catch them as I check the resistors.

Heathkit SB-101 What did he say?.
Looking over the front controls I found the AF Gain pot was very tight and did not want to work. I pulled if from the face plate, placed a napkin under it, then added a couple drops of 3-in-1 oil to the shaft. I let this set for about a half hour the reattached the knob. It was still a bit tight but after working it a few reps it became loose and moved as normal again.

Before starting into checking resistors, I decided to clean the face plate. It is in great condition with a little dust and a light splatter of house paint. This all cleaned up with Awesome (I get it at the Dolor Tree). It's a great cleaner for just about everything.
Before:

After:

Next I'll check over the circuit boards and wiring while I wait for parts. I'm hoping to apply power this Friday or Saturday

Aug 22, 2024
I spent some time going over resistor values and was pleased to find that the sampling I did (about 15%) were within tolerance, capacitor wise only 5 need replaced. There are four electrolytic and one non-polarized. The wiring looks very good with no noticeable flaws, I found three mods one which removes the 6.8Mhz trap. I did a continuity test of the ground plain and it tested good. This is an area that can give you major grief.

Heathkit SB-101 Belts don't just hold up your pants!
Up next was to replace the belts for the drive controls. This isn't a difficult job but it did have an issue, more on that later.
First the Driver Preselector control. This has two belts and is removed by loosening a collar just under the control bracket. This allows the shaft to slide out of the bushing in the RF cage.

At this time it's a good idea to use Emery cloth and clean up the ends of the shaft. This gets rids of decades of built up grime and grit. I slipped the Belts on, replaced the shaft into place making sure the pulleys on the shaft lined up with the pulleys on the capacitors. I used 3in1 oil vs. grease, grease has a tendency to get dried up and can attract dirt, but do as you are comfortable with.

Next to replace is the belt for the Final control. To remove it, loosen the two set screws on the plastic connector just inside the RF cage, then you can slide the shaft out and slip the belt on.

Heathkit SB-101 Oh snap!
Even the best laid plans of men and mice are wrought with danger, or something like that.
The coupler Heathkit used to insulate the control shaft of the drive control from the variable capacitor is a piece of plastic. I'm not sure what type but over the decades they become brittle, while reattaching the coupler to the capacitor it broke on me. D'ohhhh!

I wasn't tightening it much, but just enough to break it. Now I have a couple of couplers on hand but this is special because the shaft is a smaller diameter than the capacitor's shaft. I got lucky there's another screw hole that allowed me to tighten the coupler to the shaft. This worked fine but there was a chunk of the coupler missing. A little JB Weld fixed this problem. It'll hold fine as the pressure required to move the capacitor is minimal, I do plan to find a suitable replacement.

With the emergency resolved everything is back together and the new belts look good!

Still waiting on capacitors so I think I'll start going through the tubes. I'll run them on a tester but I'm betting they are good from the looks of them.

Heathkit SB-101 Fire in the bottles run boy run!
Well I spent the day testing the tubes and found out they all check out very good, no leaks and the lowest rating was 70%. There are a couple my little tube tester won't test but with 99% being good I have faith!

With the tubes cleaned and tested I put them back in their sockets. Starting to look good!

The caps arrived and these worn out guys were replaced. One checked good, the other was far from good.

Heathkit SB-101 The pucker factor!
Well the tubes are checked and in, the caps replaced, the boards cleaned, guess there's nothing left but to hook it up to the power supply and flip the switch.
I'm not an expert at this but I've done a few yet it still amazes me how nervous I get the first time I apply power to a project. You go over everything and look for anything that might cause that magic smoke to be released. Well here goes everything...

IT WORKS! Well kinda. It lit up good, nothing popped and it didn't blow a fuse. BUT, there's allays one of those, there wasn't any receive.
My heart fell to the floor, I was so excited to refurbish this old gal back into operation and no receive. I took a break, had some coffee and looked in the manual for troubleshooting tips. One of the things i love about Heathkit is they usually have a very good troubleshooting guide, this one didn't fail me. Going through it I found a tube in the audio section that wasn't on. Now the tube tested good so that tells me to check the socket. I did a voltage check and all was good, this means either a dirty or bad tube socket.
I have a set of wire brushes that go from a very small size to about 1/16" in diameter, these are perfect for cleaning tube sockets. Knowing how hard replacing a tube socket is on this radio I opted for a good cleaning first. I used a brush along with some alcohol. Next I took a piece of emery cloth and lightly cleaned up the tube pins. I put it back together and let it warm up, after a couple minutes I heard this!

WOW, it works! I did a test of the transmit and on 40M it tuned up to about 50 watts on CW. This is low and could be the 6146 final tubes need cleaned or they may be soft. From here I'm going to remove the tubes and do a deep cleaning of the sockets and tube pins.
I have a proof of concept that it works, it just needs a little more TLC, then I need to wire up a mic and see if the audio section works good. Stay tuned...

Aug 27, 2024
Whew, what a job that was! I went through each tube pin on each socket and cleaned them, then I polished up the tube pins. The result was well worth the effort. I noticed the receive was much better and over all performance was improved.
After this the PO was still down around 50 watts, I had a matched pair of 6146B's so I tried them and they tuned up to full power out. At this point it's running properly with full output in CW and SSB, my next step was trying for a SSB contact. I wired up a Shure 444D and jumped in and made a couple of contacts with very good results, audio reports all said the audio was clear and loud.
I've let it idle for a few hours at a time and noticed no drift in the VFO, no drop off in power, and most importantly all the smoke stayed inside! LOL
Here it is after a few QSO's:

While the majority of the resistors are within tolerance, these two bad boys were not!

These are in the first IF stage and are banded as 100K Ohms, one measured +600K and the other over 1Meg Ohms. These are part of the meter zero circuit that wasn't working. Replacing them solved that problem!
Those two resistors are 1 watt each, in my collection of parts I have no 1 watt resistors. I'll fix that issue! So not wanting to wait a few days to get one in and even having to wait for Midwest Surplus to open, I tried a couple of 3 waffers. Today's resistors are by far smaller per wattage rating than 40-50 years ago, this worked to my advantage in allowing just enough room to mount them. If I did this for money I would have just replaced them with the proper size, but I don't. :)

I was contacted by club member Dick, WA4PLL concerning the broken shaft coupler. He said if I gave him the dimensions he could 3D print one for me. I took him up on his very kind offer and the end product was a perfect fit, he even tapped and inserted the setscrews. It looks great and works like an OEM part, a big thank you Dick!

So I'm just about ready to put it back into the case and inline! Two things left to do, set the bias voltage then figure out why there's no response from the S-meter. Every other mode works, plate, grid, HV, ALC, just not working with received signals.

Aug 31, 2024
Heathkit SB-101 Good Lord what did I do?
First, here's where it's going to sit when all is said and done. This is my collection of mostly Heathkit gear that's been restored.

Now back to work. I ran across an issue with an electrolytic capacitor I had replaced, while doing some voltage checks I touched the top of it and it nipped me! I put the VOM to the top of the cap and it read 170 VDC. Ouch, First thought was I put it in backwards, nope it was right. I figured it was leakage so I replaced the New cap with another new one. This time it read below 1 VDC and dropped to zero, that's OK.
I adjusted the bias and zeroed the meter and everything seems OK but not great. Receive is fine, audio is a bit weak and very minimal movement on the S-meter. The RF Gain works so the AVC should be working. A big problem with troubleshooting this board is it's position behind the front panel controls, this and I had previous issues with the 6BN8 tube socket (This is a double diode/triode tube this is the product detector and generates the AVC voltage) I really had no option but to remove the board so I can check it and clean it up. There's a bunch of wires attached to this board. wish me luck putting it back together.

With the board pulled I can start checking each component on the board, then re flow the solder on the tube sockets. I have already found a pair of 56 Ohm resistors the were out of tolerance, one only by 30% but the other was by nearly 80%.
56 Ohm is an odd ball size, one I don't have. I do however have plenty of 33 and 22 Ohm resistors and together that's close enough.

Here both are installed, they both measured at 55 Ohms, spot on.

I'll wind up spending a day or two on this board. Besides replacing bad parts I need to prep the board for the wires to be reattached, this is very important because I won't have to curse as much during the process. LOL

Aug 31, 2024
Heathkit SB-101 A new lease on life!
Here is the finished IF board ready to be reinstalled. I replaced several resisters that were out of specs. I had to make sure all the holes for the wires were clean of solder. I also took the 140W soldering iron and re-flowed all the tube sockets, this cleared up an issue with the 6BN8 tube cutting in and out.

Here the IF board is set in place, next I'll try to rewire the board. Thankfully the manual is well written and clear when it comes to this.

That went really well, the manual was a great help and very concise. I felt pretty good and held my breath when I applied power back to the board...

My efforts were rewarded with the soft, warm glow of tubes! What a beautiful sight!

Heathkit SB-101 My "D'ooohhhh" moment.
Often we get so caught up in a project that we'll forget the most important of things, and so I had my moment.
After rebuilding the IF board I turned to the last issue that had cropped up. The receive had dropped and the S-meter no longer worked. I was still hearing signals albeit they seemed attenuated, I started looking over the voltage and resistance charts and checked everything out. Well a couple of the voltages were off and the resistance readings were pretty much spot on, overall everything looked good. I rechecked tubes, re-soldered parts, but still no change.
My friend Gary K4MT had me hook up a signal generator to the antenna jack and send an 80M signal through the receive section, sure enough the meter responded as I varied the voltage. So now I know the circuitry is good, WTH could it be? Well I did what you should do and read through the manual. And there it was, a single sentence around the countless paragraphs of words, telling me about the receive antenna and SWITCH on the back of the radio.
Now I knew about this from going over the manual when I first got the radio, but that information was buried deep in my brain. D'ooohhhh! Needless to say moving the switch back to COM and not REC made a world of difference. The audio filled the room, the S-meter was working, all I could do was laugh.

With everything back together and working I proceeded to do an alignment. I skipped the receiver because it is pretty close and not off to rick moving the coil slugs. I did set the BIAS voltage, aligned the marker generator and band dial, checked the oscillator coils, and made sure it tuned up on all bands.
80, 40, and 20M tuned up to full power (100W). 10M is rated for an output of 80W, I was only getting 30W. 15M was making it to about 90W. I neutralized the finals and eeked out another 10W on 10M. From here I opened the cover of the tuning coils to access the wafers for the band switch.
They were pretty dirty and carbon-ed up. I cleaned them with Q-Tips and alcohol.

Q-Tips will leave small pieces of cotton behind. A small soft bristle brush or compressed air will remove them.

After the cleaning I went through each band and did a tune up in the middle of each segments. 80M netted around 110W, 40,20,15M tune up to 100W, and now 10M tunes up to around 70W! This is as good as it gets!
So now it's back into it's case and back in line!

I wish to thank the following for their help.
BARC
Don, WC4D
Dick, WA4PLL
Frank, WS8B
Gary, K4MT

Page updated Sep, 05 2024.