KLH Model Eight FM Radio (1962)

The KLH Model Eight (8) FM radio is a prized collector's item, scarcer than the Model Twenty One that succeeded it. Both were designed by Henry Kloss with one goal in mind: to create the world's best-sounding FM radio in a compact tabletop cabinet.

First Look

Here is my Model Eight as found, before I had done any cleanup or restoration. The radio and speaker are in identically sized cabinets, which I stacked for these photos. The front controls are simple: power, treble, volume, and tuning.

From behind, you can see that the speaker has a back cover but the radio does not. The two are linked by a 30-foot long cable. Big cleats on the speaker's back cover make it easy to stow excess cable:

Notice the corner joints in the rear cabinet views. These are early Model Eight cabinets, made of solid walnut; later cabinets were made of veneered wood.

The radio's chassis is compact, with a few rear connectors. Two upper terminals let you connect an external FM antenna. At lower left are two jacks for the speaker cable. The tuner output jack can be used with an external amplifier. The multiplex jack is for use with an external stereo multiplex decoder (and stereo amplifier).

Trying Out the Model Eight

When I powered up the radio using my variac, I found that it worked nicely, with good sensitivity, excellent tone, and not a trace of hum (which would signal bad filter capacitors).

The only defects were some scratchiness when turning the volume control and, less often, the tuner. These can easily be remedied with a little electronic cleaner when I take the chassis out of the cabinet. When I get to that stage, I can also check the filter caps with my capacitor tester to make sure they're up to snuff).

The cabinets are in nice shape, overall, with only a few little boo-boos that will be easy to eliminate. The speaker grille cloth has some visible stains. If those can't be cleaned away, I'll replace the cloth with a comparable linen fabric.

Cleaning Up

My Model Eight's chassis was pretty grubby, covered with greasy dust.

The view underneath was more inviting. No cleanup needed here.

The build quality of this radio is impressive. The solder joints are extremely neat and every one was tagged with a green marker, possibly a quality control measure to show that it passed inspection. The box at upper right in the photo is the tuner cage, soldered shut to exclude dirt as well as RF interference.

After dusting off the air variable capacitor, I lubricated it to eliminate intermittency and scratching sounds when tuning. The yellow arrow points to the ball bearing structure at the front of the tuner frame:

With the chassis tilted forward, I put a tiny drop of light oil into the ball bearing mechanism using a toothpick, and then turned the tuner all the way back and forth a few times to spread the oil. I left the chassis tilted forward for a couple of hours to let a little oil migrate down into the vernier tuning mechanism.

The arrows in the next photo show two more areas that got a wee bit of CAIG electronic lubricant:

As with every restoration, I also cleaned every pin on each of the seven tubes and applied electronic cleaner to the Treble and Volume potentiometers.

I let the radio sit overnight, to make sure all of the electronic cleaner had evaporated from the potentiometers. When I tried it the next day, it sounded fabulous. The cleaning eliminated all noisiness from the tuner and controls.

Cleaning the chassis took much longer. Its plating was oxidized as well as dirty. I began by mopping off dirt and grime with isopropyl alcohol, using rags, paper towels, and Q-tips. After that, I brought back the shine using metal polish and pieces of non-scratch plastic pads. I cleaned off the polish with damp paper towels and then polished with a cloth. This photo shows the chassis after I had done a strip near one end.

Now, the chassis looks much more civilized.

Of course, the electrons whizzing inside don't care whether the chassis metal is dull or shiny. I don't bother with this in many projects, but the Model Eight is so nicely built that I like bringing it closer to its original appearance.

Cabinet Restoration

Let's start by cleaning the Model Eight's front panel. This painted Masonite board cleans up easily with Windex and a soft cloth. Don't scrub it with anything abrasive, lest you ruin the paint.

The speaker grille cloth is trickier to handle. In this earlier photo, you can see a stain meandering across its lower part:

Grille fabrics are not intended to withstand wetting, and there's no way to know whether this stain came from spilled coffee, alcohol, or something else. We also don't know what sort of dye (if any) was used in the original fabric. If the dye is water soluble, wetting may have unpredictable results.

Notice the lighter appearance of the cloth over the circular holes for the speaker drivers. Perhaps air moving through those openings kept dust from settling on those parts, whereas the rest of the cloth was glued stationary to the board, where it could collect more dust, cooking fumes, etc., over the decades, eventually darkening with grime.

In many old radios, the grille cloth is lightly glued around the edges of a big opening, and with care, you can remove it for gentle washing. Not so with this cloth, which is glued to the mostly-solid Masonite speaker board. Trying to peel it off would likely destroy it.

Nothing ventured, nothing gained. I began with clear, warm water, dabbing it on with a clean cloth and then pressing off the excess with another cloth. Following that, I left it under gentle heat from a lamp, to see how it looked after drying.

The first attempt wasn't encouraging. Dabbing with water lightened the stain somewhat, but it also lightened the surrounding area (duh), so the stain was still evident.

I suppose the lightest areas on the cloth represent the original color, more or less. One approach would be to keep dabbing the entire cloth, until it had a pretty uniform light color and the stain was much reduced.

I didn't do that because the cloth had begun to shrink. Look at the lower left side, and you'll see a space starting to open up between the cloth and cabinet, whereas the cloth is tightly pressed against the cabinet in other areas. The cloth was also loosening a bit in that corner.

I haven't ruled out treating the whole cloth, but perhaps there will be less shrinkage if I use a non-water based solvent, something like lighter fluid or Goo-Gone.

Since the radio and speaker cabinets have only minor scuffs, I'll freshen them up by applying Howard's Restore-a-Finish. This treatment isn't suitable for a badly damaged finish, but it works for concealing the little stuff.

Stay Tuned

That's as far as I have gotten at this writing (November, 2011). I'll update this article after the radio is restored.

In that update, I'll also draw some comparisons between this Model Eight and my KLH Model Twenty One.