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A new tuner, and progress toward a new shack

For months now I’ve been struggling with my horizontal loop antenna. It’ not cut to exact resonance, it’s too low to suit me, yadda yadda – but it’s what I have right now. I have it connected (via about 50′ of low-loss LMR-400 coax) to an ancient LDG RT-100 remote auto tuner, but that tuner has struggled and largely failed to find a suitable match on nearly any band. Most of the time it only gets down to 2:1 or 3:1, so I use the rig’s internal tuner to make up the difference. My tuning process on band or large frequency changes is:

  • Disable the rig’s tuner
  • Press and hold the TUNE button on the remote keypad, assuming I’m using the FT-1000
  • Press the TUNE button on the RC-11 remote box
  • Wait for that to finish tuning
  • Release the TUNE button
  • Turn on the rig’s tuner and wait for it to find a match

After a long bout of planning to move the RT-11 closer to the feedpoint, looking for a later RT-600, rejecting the idea of several other remote tuners because they’re really not designed for balanced antennas, and deciding not to buy an RT-100 for various reasons, I decided to try a completely different approach just to see what happens. I pulled the trigger on a used LDG AT-600Pro. It’s a desktop tuner rated for 600W, with an A/B antenna switch built in as well. My plan is ti use that, remove the RT-11 from outside the house, and replace it with a good common-mode choke.

The tuner arrived yesterday, and I set it up just to see how it works. I haven’t de-cabled the RT-11 yet, so I put it in by pass mode for now. To my delight, the RT-600 has no trouble matching the antenna to 1.5:1 SWR or batter on any band I tried from 80 through 10 meters. No using the FT-1000’s tuner, and the AT-600Pro remembers the settings by frequency, so after switching bands it generally tunes in a fraction of a second. It’s almost effortless. I have a lightning arrestor arriving tomorrow that I can use to bridge the two coax runs and get the RT-11 out of the picture, and I’ll wind a common-mode choke from the excess LMR-400 and a stack of FT240-31 toroids I have coming.

I’m utterly thrilled that the AT-600Pro does so well. Now I can run the full 200W of output power on the FT-1000MP Mark V if I want to. Using gthe SB-101 or HW-16 will be easier – I can tune them into a dummy load and let the tuner do the heavy lifting there. I can only conclude that the RT-11 is crippled. I thought it was dead back in 2005 or ’06 hen it stopped working with the flagpole I was trying to use. hen I resurrected it, it seemed to work OK… but I suspect it’s got some sort of internal damage. Maybe a bad relay, maybe a stuck or dead driver line, I don’t know. Doesn’t matter; I can junk it with a clear conscience.

On another front, this morning I finished building the new run of shelves that I’m hoping will be enough for all the storage I need in the workshop. I’m clearing out some old junk, and the new shelves are much stronger and aren’t sagging (and won’t sag, either). The idea is to empty out the shelves currently taking up part of the 10′ of wall space I plan to use for the new ham shack, then move my large Ikea Galant desk from my old office upstairs down to the shack. That will give me a 110″ long, 31.25″ deep operating desk, with an “L” on the left end that’s 47″ by roughly 23.5″. I’ll have a substantial shelf overhead for the network equipment and to suspend a pair of monitors. I should have plenty of room for all of the station equipment without much stacking. I’m really looking forward to being able to have the FT-1000, SB-101, and HW-16 stations all set up and easily accessible. The biggest challenge will be keeping the cabling from turning into a rat’s nest of tangles. I need to give that some thought.

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Baby steps

I’ve been working a fair number of POTA stations lately – I have a Sapphire award for over 75 stations “hunted”. Woo-hoo! Not a big deal, really. Most have been FT8 or FT4 data modes, which I barely count as contacts. Going by the award endorsements, at least 20 have been phone, the rest data modes. Until today, I don’t think any have been CW. One of the reasons is that they’re almost always running 20 WPM or better – way too fast for me. I have, however, been working on a (temporary) solution for that until I get my copy speed back up.

The FT-1000 has an internal “contest keyer”, at least in terms of what qualified in the 90s and early 2000s. Yes, of course I have a few keyers around, but I kind of wanted to be able to use the rig’s internal memory keyer and dedicate my MK-1 to other radios. I bought a cheap-ass but working version of the Yaesu FH-1 remote key pad. The only difference between that the FH-1 is the button markings. Anyway, I set up one memory with just my call sign, and another one with the exchange – “TU 599 NE 5NN NE K”. Now all I need to do is listen to the POTA station’s call sign a couple of times to get it all, and I can use the keyer to send what I need to.

I worked N2DA on 20 meters this afternoon, and got my first CW POTA contact in the log… and my first CW contact using the Mark V FT-1000.

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An Embarrassment of FT-1000s

I’ve been scouting for a replacement for the TS-850 for a while now. Something maybe a little newer, but not one of the new rigs that puts most of the functions on a screen. Call me old, I like my knobs and buttons. I don’t like wading through menu layers to get to stuff I change fairly often. I never did fall in love with the TS-850. It’s a fine rig and all… but it replaced a TS-930S, and while I appreciate the relief from the constant power supply issues, the receiver never has really measured up. I know that’s a high bar to set.

At first I was thinking about the FT-1000 series, Yaesu’s flagship contesting radio from the late 90s through the mid 2000s. The original FT-1000 and FT-1000D was superseded by the FT-1000MP, and then by the Mark V in two different flavors – the 200W Mark V FT-1000MP, and the 100W Mark V FT-1000MP Field. Nice radios, but they’re all 20+ years old. I also considered the Kenwood TS-590SG, a much more modern, DSP based rig. Then there’s the Elecraft K3. A new K4 is nice, but at nearly $7K it’s just not in the cards. the K3 is highly regarded and falls somewhere in the $1500-2500 range, depending on the many, many options and filters available for it. I thought about the TS-950SDX, but pretty much nobody recommends that – it seems like a continuation of the 850 with audio DSP. 

I’d pretty much decided on the K3, albeit a little reluctantly. Some of the functions seem a little more menu driven than I’d like, but it’s pretty much universally loved. I hadn’t pulled the trigger yet, waiting on a deal I liked. What I wanted would cost me over $1K, probably closer to $2K, and I wanted to find the “sweet spot” of all the options I wanted, but at a good price. 

Then someone listed an FT-1000MP for $600, all in, shipped to my doorstep. I just couldn’t pass that up. I bought it. It arrived. I fixed one problem – a dead CAT serial port that took a $1.30 chip to fix. It’s awesome, I love it. It exceeded my expectations. I used it for SSB, for FT8, even some CW. Life was good. Sure, a Mark V Field would be nice, but I was happy.

Then someone listed a Mark V FT-1000MP – as-is, for $200. Wait, what? He was up front about his reasons. He’d had some problem or other, fixed it, everything worked until he closed up the front panel, then the buttons and LEDs quit working. He took it apart again, found a cable loose or something, closed it up, and still had a dead front panel. He decided to call it quits and sell. Well, I’d just been in the front panel of an FT-1000MP – nearly identical – days before, and encountered a very similar problem that turned out to be knucklehead me not recognizing the “zero insertion force” (ZIF) flat cable connectors, and getting a couple of them partially seated. On those connectors there’s a latching piece that has to be pulled out to seat the cable, then pushed in. These things were designed to be assembled by tiny little Japanese girls in a factory, not mucked about with by my giant ham fists. I figured I could fix this $200 rig and have an updated, newer, fancier version of what I had just fallen in love with. So I bought it.

The UPS boxes arrived yesterday. The rig has its own power supply; the 200 W final amp needs a 30 V supply, so it comes with an FP-29 switching 12/30 V power supply. I put it in the bench and, sure enough, the display was OK (if a bit dim) but the buttons and LEDs were unresponsive. It did take longer than I thought to get it working, but in the end I did. It wasn’t a flat cable; it seems to have been just the routing of the high-voltage wires for the display’s CCFL backlight tube. Last night I put it on the air, and I have to say, the upgrades to the original MP are pretty impressive. I don’t know that I will even need to move the extra IF filters I bought for the first rig over to it.

So, now my tiny operating desk has a TS-850, and above it a shelf with an FT-1000MP and a Mark V FT-1000MP stacked on top. A little overkill, sure. And yes, I’m sure I’ll sell two of these rigs. I had been keeping an eye out for a Mark V Field, the 100 W version, because my remote antenna tuner is rated for 125 W maximum, but as it turns out the 200 W Mark V has a convenient menu setting to set the maximum output power to 200, 75, or 10 W. It also has the typical 100/50 W switch inside the rig, same as the TS-850 and the older FT-1000MP, but I don’t know what that will actually do on this rig. I have the radio set for 75W max. Is it perfect? No; it has one mismatched knob from a different Yaesu rig that isn’t obvious but I’d like to replace it some day. It’s pretty nice cosmetically, though, and seems perfectly functional. I spent an hour exploring different features, some I’ll use and some I may not, and there are still some I haven’t tried out. The transition from the older rig to the Mark V is almost as different as going from the TS-850 to the FT-1000 was.

If someone had told me a year ago that I’d have a stack of radios like this on that desk, I’d have thought they didn’t know me very well… but when things line up, they line up, and here we are. Now I just need to get the 850’s ALC issue fixed so it’s working properly again, and get it listed for sale. Then I’ll pull the filters from the FT-1000MP and list that one, along with a few other pieces of gear I don’t need. Meanwhile, I’m exploring a newfound enjoyment of chasing POTA stations and finding new DX countries on FT8 and FT4.

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It’s New Radio Day!

Woohoo! It’s always an adventure to un-box a new radio. In this case it’s “new to me”, but qualifies as “vintage” or “classic”, I guess. I picked up a Yaesu FT-1000MP, manufactured in 2000 – so, 26 years old. That makes it a late production 1000MP, made just as the successor Mark V FT-1000MP was introduced. This was Yaesu’s flagship HF contesting rig at the time, retailing for $2500 in 2000 – which would be just a bit under $5000 in 2026 dollars. It was pretty advanced for the time, with dual receivers, DSP in the audio chain, and quadruple conversion. These were a huge hit with contesters, and the price on the used market has fallen well under $1K for a clean example with no defects.

The radio arrived yesterday from a ham in Wisconsin. I unboxed it and gave it a quick bench checkout to make sure there were no major issues. Aside from a little dent in teh top speaker grille – easily corrected once I have the top cover off – there are no cosmetic issues with it. The display isn’t quite as bright as I’d like to see, but it’s adequate; these old CCFL backlit LCDs are aging out and will all eventually fail. Fortunately, replacing the backlight with an LED strip is neither difficult nor expensive. I did it to my TS-850 last year.

After setting it up on the operating desk, I did some side by side comparisons with the Kenwood. Both seem to have about the same sensitivity; I could copy both stronger and weak signals on both rigs with essentially identical readability. That shouldn’t have been a surprise, really — the TS-850 was no slouch for its day, either. I switched both rigs to the 500 Hz CW filters. The Kenwood’s is an optional crystal filter I had to buy and install, the Yaesu has one installed in the second IF (8.215 MHz) from the factory. It was pretty obvious that the FT-1000MP was a little better – again, both were clear and readable, but there was a little less noise on the Yaesu, and it was less tiring to listen to. Later I figured out that I didn’t have the DSP switched on at the time; turning that on makes it sound even better.

I’ve spent a little time exploring how to use the rig. It will take a while to learn all of the features and functions, but there are already a coupe that surprised me. It doesn’t surprise me that there is a sub-receiver, obviously. I figured that was handy for contesting, but didn’t really see how I’d use it during casual operating. I was surprised, however, by how quickly I figured out that yes, it is nice to be able to tune around listening for other stations without changing your operating frequency. It’s so quick and easy to just hit the “dual” button to get both receivers in the headphones.

Tuning the RT-11 remote tuner is pretty quick and easy… though it will be even quicker and easier when I have a remote keypad plugged in (Yaesu FH-1 or FH-2 or equivalent). That has a dedicated button to put out a carrier at a selectable 10, 25, or 100W power level for just this purpose. For now, I turn off the internal tuner and the keyer, set the RF power control to about 12 o’clock, and key the rig with either paddle. That puts about 25W out to the antenna. When the RT-11 finishes I turn on the rig’s tuner, hit the TUNE button, and while it’s doing its thing turn the RF to max and turn the internal keyer back on. The whole process takes only a few seconds.

So far the only glitch I’ve found is a non-working “A->B” button. This is the one that copies the main VFO frequency to the sub VFO. I do miss that function and I’ll need to fix that button. I’m hopeful that Yaesu used standard tactile switches for the panel and not some dome switch pad. Over the next few days I have some things planned that will require taking the overs off, so I’ll have a look then. (note: This turned out to just be me not knowing that you need to press and hold the button.) On the schedule for this rig:

  • Install the 250 Hz CW filter that I have coming on Monday
  • Install the TCXO-4 module that should arrive today
  • Replace the internal backup battery
  • Check out the front panel buttons to see about fixing the A->B button
  • Get a look at the display and see whether I want to install an LED backlight kit, or DIY a solution
  • Buy or build a remote keypad – this will give me a single TUNE button as well as the ability to use the two 20-character and four 50-character CW keyer memories

I’m pretty happy with the rig. It’s impressive looking – about three inches wider than the TS-850, all of that extra space packed with knobs and buttons. We hams just love knobs and buttons! I like the way it sounds; I like the fact that it’s AC powered so I can remove one power supply from the desk. I’ll operate it for a while before deciding whether to buy any additional filters for it. The factory complement includes 2.4 kHz SSB and 500 Hz CW filters for the main VFO. There are also are are 2 kHz SSB and 250 Hz CW filters for the second IF available, plus 2 kHz, 500 Hz, and 250 Hz for the third IF and 500 Hz for the sub receiver. Filters are not cheap; I want to see what the IF shift & width controls and the EDSP will do before deciding what (if any) I want to install other than the 250 Hz 2nd IF filter I already have coming.

I’ve called CQ a few times, but there are at least two separate contests going on – one SKCC and one not. I did have one guy answer but he disappeared, so no complete QSO yet. I’ll keep trying. With the keyer set at 10 WPM it shouldn’t be long before I’ve got a couple in the logbook. I am intentionally holding off on ordering cables for the Digirig Mobile; I want to stick to CW and phone for a while.

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It’s always something…

The other day I took the TS-850 apart, once again. For whatever reason (more about that later), I was only getting about 50W output on any band in CW mode. I did the ALC adjustments and got it stable at 100W where it should be… and along the way, figured out that it may have been “operator headspace” all along. There’s a CAR (carrier) control that I was suing to set the power, and also a “PWR” (power level) control that, honestly, I’d forgotten was there. I may have had it set to a lower level. Who knows? It’s working now.

I’d had to disassemble a substantial part of the “shack” to get the TS-850 set up on the bench. I had to un-cable the radio, pull the power supply, then unhook the Heathkit HM-102 power/SWR meter and the dummy load. In order to do that, I had to de-cable and move the Heathkit SB-101 and its companion SB-600 speaker cabinet with the speaker and power supply. Those sit on a shelf that I built that sits over the top of the TS-850 and some other gear. It really is kind of a major operation to take something out of the operating position desk, which is something I hope to remedy sooner or later with a bigger, roomier desk.

I got everything done – the power output back up to 100W and I re-installed the TCXO that I’d pulled for some reason a few months ago. I buttoned everything back up and spent the better part of an hour getting all of the gear re-installed and cabled. While I had it all apart, I decided to re-do the cabling. I have the antenna and the dummy load on an A/B coax switch, the input of which is connected to the HM-102, which is itself connected to the SB-610 station monitor. In order to switch from one rig to another I had to un-screw that rig’s antenna coax at the input of the SB-610, and connect the other’s coax. I decided to install the MFJ 6-way coax switch to all of the radios, and connect that tot he SB-610 to make it quick and easy to switch rigs. I wall mounted both coax switches and got everything cabled up, double-checking the connections as I went.

That evening I wanted to try some CW contacts with the SB-101. After tuning into the dummy load, I switched to the antenna and called CQ several times. I could hear a few other stations up and down a couple kHz from where I was, but I had no replies. I decided to switch to the TS-850, so just flipped the 6-way switch to position 1 and tried transmitting. The Kenwood showed no RF out – none. Even with the CAR and PWR turned to the max settings, nothing at all. Somewhat discouraged and more than a little irritated, I shut everything off and went upstairs.

The more I thought about it, the less convinced I was that both rigs had failed at the same time. I decided that I must have messed up the coax cabling, or had a bad cable. I went back down and did some troubleshooting. Starting with just the dummy load on a short coax jumper, I tested the TS-850 – full power out, no problem at all. I then went through the whole chain, connecting the dummy load at each junction and testing for power output. The 6-way coax switch tested good. Then the SB-600 – good. Then the HM-102 – good. Then the 2-way coax switch – Nope! No output.

That switch, an old MFJ-1702 that I’d picked up use years ago, has failed. THere’s nothing apparently wrong with it mechanically, I took it apart and checked for broken, corroded, or misaligned parts. It tests fine with an Ohm meter, no shorts or opens in either position. It does not, however, work with either radio in position A (the antenna) and intermittently fails in position B (dummy load).

Given its age and all, I decided not to try and troubleshoot or fix it. It’s going into the trash, and I’ll replace it with a good quality Diamond CX210A. It’s more expensive than the many options I see from Diamond, Opek, and many others including a slew of no-name Chinesium garbage that all look identical to the MFJ I’m replacing. In the mean time, I’ve connected the antenna coax directly to the HM-102.

Oh, and the reason for the low output on the TS-850? I’m honestly not sure. I suspect, however, that I simply forgot that there is both a CAR control for the carrier level in CW, AM, and FM modes, and a PWR control that is global in nature – it works in all modes, regardless of the MIC or CAR settings. Given that the most I’ve been able to get out of the rig while working FT8 without the ALC kicking in has been between 50 and 75 W, I suspect I may have just inadvertently had the PWR control set to the point where it limited CW output to 50 W. I really don’t know for sure, but I suspect that’s the root cause. Hey, at least I discovered the failed switch now rather than having it intermittently fail over some period of time and potentially cause more problems.

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The New Shack

I realized I haven’t posted anything since early this year when I struggling with equipment located upstairs and all of the RFI and other issues that caused. Since that time I’ve made a good deal of progress.

All of the radio equipment is now in the basement. It’s not idea as far as I’m concerned, but it is what it is. From a practical standpoint it makes sense. I can get coax straight out the back of the house, which makes grounding and antenna installation so much easier. It’s unfortunate that everything is crammed into a very small space. It’s a little built-in “nook” probably intended for study or something. A 51″ wide countertop, 24″ deep (if that); wall cabinets mounted above so it’s a little constrained both horizontally and vertically. A couple of duplex outlets, a phone jack – no Ethernet, and no way to get it there either. Doing any kind of wiring would require major demolition and construction. Just getting RG-8/U and a flat cable for the remote tuner control into that space took a lot, and I do mean a lot.

The antenna is now a 135′ (give or take a little) loop in a triangular shape around the back yard. The feed end is at about 16′; the two legs go out to two maple trees where the wire is up between 25 and 30 feet. Again, not ideal, but it’s what I could manage to get up in the air. A 1:1 balun at the feed point connects the antenna to 50′ of LMR-400, which connects to an LDG RT-11 remote tuner, and from there to the shack via about 35′ of RG-8/U.

I’ve successfully run 100W+ on SSB and CW with no interference with anything else, no RFI in the house, no issues with breakers. The RT-11 doesn’t match the antenna in all cases; on most bands I need to also use the TS-850’s internal tuner. Surprisingly enough, I’ve worked a couple dozen countries using 25 to 50 W on FT8, and one night worked a couple of Russians (grids LO02 and LO33) on 20 meter SSB. Log entries show that 40 meters is almost all US and a smattering of Canadians, with a few surprising exceptions – Japan, Spain, and France. I attribute those to guys in those countries with good beam antennas! Not surprisingly, the higher in frequency I go, the better the DX results are. I’ve even worked a few US stations on 80, but of course that’s pretty clearly NVIS so I don’t even try much.

I have the TS-850, SP-31, FT-817nd, the keyer, and a couple of Astron DC power supplies on the desk. I built a shelf for the SB-101 and SB-600/HP-23. On the other side of the desk is an SB-610 monitor scope I picked up, an HM-102 power/SWR meter, the control for the RT-11, and a coax switch to switch between the antenna and a dummy load.

I am planning a new shack, though. I’m slowly cleaning out my basement workshop and storage area. My plan is to revamp the storage area with nicer cabinets, and build a 6′ long operating desk about 30-32″ deep in one corner. A 4′ workbench will go next to that. I’ll have room for everything, and more room for a straight key and paddle in a more comfortable operating position. Right now things are a little cramped.

I’ve worked a lot more FT8 than I would like to admit, but I’ve also worked some SSB, one SSTV QSO, and even a PSK and an RTTY contact. RTTY and SSTV were firsts for me. None of those are confirmed; the RTTY and PSK contacts got lost in QSB but the SSTV was solid. I just wish I’d saved the darned image, I’m really bummed that I lost that. I blame the software.

Anyway… onward.

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RFI from the shack, again, naturally

The other day I decided to try setting up the SB-101 and do some testing of the setup with the antenna tuner. As I tuned up with a few watts, things were OK… then I turned up the drive past 50 W, and things got wonky. The monitors on the PC flickered, the PC beeped, it logged me out, the CO monitor in the hallway beeped, and a few minutes later I noticed we’d lost our Internet connection. After a little investigation I found half a dozen GFCI/AFCI breakers in our main panel had tripped and had to be reset. It had dropped power to the entire kitchen, so the router was powered off.

Obviously there’s an RFI problem. I have all of the equipment grounded to a new copper bus bar using 12-18 inch flat copper braid, and the bus bar is grounded to the household AC ground. Ah, there’s the mistake. That puts any stray RFI onto the house electrical ground, which the breakers interpret as a grounding problem.

The shack is on the second floor for the time being, in the “spare” bedroom that has been my office for the past 15 years or so. I’m using a 71′ long end fed wire, with about 18′ or so of counterpoise. I’m feeding it through an MFJ tuner, but that means there’s a good deal of RF on the feedline inside the house before it snakes out through a window.

The eventual solution will be a remote auto tuner at or near the feedpoint of the antenna, outside and well away from the house. The interim solution? Limit my output to QRP levels. I can work some SSB with normal power, but CW or digital modes using much more than that is a recipe for electrical problems. It’s less than ideal, but once our new deck is built I should have a good mounting point for a remote tuner, and a feedpoint from which I can string up a full wave loop for 40 meters that should work pretty well on most other bands too.

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The price of neglect…

Last summer I installed a mini-split heat pump on the garage. My goal was to make the garage usable as a work shop (and smoking lounge) year round, without sweltering heat in summer and frigid temperatures in winter. The summer thing worked out pretty well; the heat pump seemed to keep up and it didn’t impact the electric bill more than it was worth.

This winter was a little different story. I know the garage is a little leaky, but the unit seemed to struggle to keep it much above the low 50s on cold days, and my last electric bill was about double what we usually see. I was considering adding a supplemental heat source, and truthfully a little disappointed. The unit’s specs said it would operate down to something like -4 F.

Yesterday afternoon I wanted to make a change to the aiming of the air vent, and noticed that there was barely any air flow. What little there was was quite warm, but it was obviously not enough to do much good. Hmmm. I grabbed a ladder and checked the intake filter on top of the unit… and found it almost totally blocked by a thick layer of brown crud.

Dummy!! After all the time I spend trying to get our rental tenants to change their furnace filters, I let this happen! And I should have known it would clog up, as I spent hours running the table saw out here to make cabinets and stuff. I rather sheepishly vacuumed the screen off and plopped the filter back in place and was rewarded with a blast of warm air that fairly quickly brought the garage up to the set temperature.

Lesson learned! I’ll be cleaning that at least monthly, and replacing the ERV filter on schedule. Things don’t work right when you don’t take care of them. I knew that and still got lazy and neglected it. That won’t happen again.

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New fenders scored!

I found a pair of “new”, as in new old stock, fenders for the Mustang listed on Facebook Marketplace. After a little digging, these appear to be manufactured by Ford as service replacement parts. Lord only knows when. They’re not 1960s vintage, as those were primed in red with the part number stenciled on yellow in the inside. These are black primed, and they had parts system stickers on them at some point that were scraped off. So I have no idea when they were produced, but the date stamps indicate they were Ford parts. They seem to be pretty decent quality, a little heavier gauge steel than I have seen on some new parts.

The old fenders are too far gone to save, and I got these for less than a single new repro part would cost me after shipping. In fact, maybe less than one before shipping. NPD carries two different brands of fenders; one is under $250 and the other over $450 per side. Plus truck freight, of course. Are the cheap ones decent? Can you tell the difference between those and the expensive ones? Don’t know, and no real way to tell. Reviews aren’t terribly helpful; one guy’s “These suck” may be another’s “The guys at the restoration shop were able to make them fit with a few hours’ work”. Whatever, now I don’t have to worry about what to buy.

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SB-101 Dial Drive Overhaul

When I bought the Heathkit SB-101, the dial drive was a mess. The dial itself, of course, was old and severely cracked. Much worse, though, was that FedEx had dropped the rig on its face – and even though it was bubble wrapped, whoever packed it didn’t bother to put Styrofoam blocks between the knobs. That would have protected the face and knobs, but as it was the main tuning dial was damaged. The aluminum skirt was bent, and the drive pulley was damaged.

The drive pulley consists of a pair of bronze washers, each with a rolled bead near the outer perimeter, which are spaced slightly apart using a tiny aluminum spacer. That assembly grips an aluminum drive ring that’s attached to the plastic dial. The raised beads put pressure on the drive ring to turn the main dial. Well, on mine, one of those bronze washers is cracked and bent. I was unable to get it sufficiently straightened out to give a solid grip on the tuning drive ring all the way around, so the knob would slip on the dial. Of course no replacement parts are available anywhere, other than from a parts rig – which I don’t have.

With nothing to lose, I decided to try something new. I got the damaged washer as straight as I could, then grabbed a 2 x 5 mm silicone O-ring left over from a coffee machine repair. I put that around the spacer in between the bronze washers and reassembled the mechanism. Success! The operation was now smooth, positive, and free of the slippage I’d experienced before.

Left to right: The shaft and outer drive washer, crack visible at about 11 o’clock. Next is the middle spacer, inner washer, end spacer, and the screw that holds it all together.

After a few days of use, however, I noticed some slipping again. I suspected there was a little oil or grease that had migrated to the O-ring, and I was right. I pulled the assembly apart and thoroughly cleaned everything with some 91% isopropyl alcohol and paper towel. When I re-assembled it, I used a #009 neoprene O-ring. It’s very close to the 5 x 2 mm O-ring I had in there before, but I was hoping that the very slightly smaller cross section and the neoprene material might give a little more traction. I also used a Q-tip with a little alcohol to clean off the dial drive ring, in case there was oil or aluminum oxide on that.

The middle spacer and inner washer, with the silicone (red) and neoprene (black) O-rings.

With everything back together, I once again had smooth, positive drive with no slipping. Time will tell how well this fix holds up, but it’s definitely better than the nearly unusable state in which I received the rig.

The new O-ring in place around the center spacer before re-assembly

So far the tuning dial has worked out OK. If it fails, I have a vague plan for a 3D printed center hub for the dial with a ring gear, and a pinion gear for the dial shaft. I understand why this might be one reason the HW-100 is more popular than the SB-100/101/102, but this may also help some owners of other SB-line gear like the SB-300/302 and 400/401.