KLH Model Twenty One FM Radio (1967)



In April, 2020, around the beginning of the global pandemic, I received an intriguing email:

From: Sarah Koenig
Subject: Hello! (and help)
To: info@antiqueradio.org

Hello Mr. Nelson,

I have a KLH Model 21, which belonged to my father, and
which I love -- it had such a wonderful sound. But now 
I can’t get it to work. It stopped turning on for me years
ago. Then recently I took it to a guy in Pennsylvania (where
I live), a collector, and he seemed to fix it quite easily --
it turned on  for him right away, in fact, which was completely
mysterious to me. He cleaned the innards a bit, and lubricated
parts of it, and I left very thrilled that I had my old radio
back. But when I got home and plugged it in -- nothing. I’ve
taken it apart to see if there’s anything obvious, but I can’t
tell. I know nothing about radios, or electronics. (I am,
incidentally, a radio reporter -- I now host the podcast
Serial -- so I have a deep fondness for all radios.) 

I saw on your website that you’d restored  your KLH 21 (it
looks beautiful, by the way). My question is: Is it possible you
could mend mine if I sent it to you? I’d be very happy to pay
for your time and expertise. 

Thanks very much. 

Sincerely, Sarah K.

From: Phil Nelson
Subject: RE: Hello! (and help)
To: Sarah Koenig

Hello, and what a pleasant surprise to hear from a radio
celebrity! (I was about to say, "public radio rock star,"
but let’s not gush.) Anyhow, I’m a big fan of public radio,
and a long-time contributor to the public stations in this area.
I’ll be glad to fix your KLH 21 -- free of charge.
It’s cool that you’re using your father’s radio. I own a radio
that belonged to my Mom, and another that belonged to my Grandma.
Both are cheap kitchen radios, but I love ‘em just the same.

I live near Seattle, so you would need to ship the radio out here.
The Model 21 is not heavy, so shipping shouldn’t cost a fortune.

Let me know if that sounds OK. I’ll send you my mailing address
and we can take it from there.
Phil Nelson

For those living under rocks during the last several years, Serial is the deservedly famous podcast that debuted in 2014, blazing a trail for many podcasts to follow. Sarah Koenig is the acclaimed host and producer.

The KLH Model Twenty One is a highly collectible, FM-only radio from the 1960s. In an earlier article, I described the restoration of my original Model Twenty One some years ago. Meanwhile, the tale of this Twenty One continues:

From: Sarah Koenig
Subject: Hello! (and help)
To: Phil Nelson

This is the nicest email ever. Thank you so very much. But I’d
like to pay you! How about I send it (from Pennsylvania, so
it’ll take a little bit to get to you probably), and you take
a look at the condition, and see how much work it’s going to 
be, before you decide about a fee. Is that okay?

So yes, please, send me your address, and I’ll wrap up the radio. 

Thank you, again. Best, Sarah

From: Phil Nelson

Sure, that's fine. That radio is less fragile than many older
sets, but it’s prudent to wrap it in some layers of bubble wrap
and then place it in a sturdy box with other packing materials.


From: Sarah Koenig

Great! I’ll send it (carefully) along.

As you’ll see, the fiberglass pillow thing is not inside;
I’m including it in the package to you, but the guy who
"fixed" it before took it out and said there
was no need for it. Perhaps you disagree. You’ll also
see that the cloth bag holding the fiberglass is falling

Also: you’ll notice the interior dowels have come loose,
and the insulation around the back interior panel is all
crumbling -- basically any rubber or insulating material
inside has mostly worn away.

Finally, you’ll see that the top of the radio has severe
damage to the wood -- that’s 100 percent my fault. I think
my younger self had a plant on top of it for a while -- or
maybe a candle?? -- which was obviously idiotic. If you can
restore the wooden case, I’d love it. But I also understand
if the damage to the wood is too severe. Anyhow -- thank
you in advance for giving it a try. As I mentioned, I love
this radio, and I also adored my dad, who died in 2014.
So I really want to get it working, because the sound of
it reminds me of him.

Sincerely, Sarah

The radio arrived in a few days, and its top indeed had a big black stain. Otherwise, it was complete, including the original acoustic pillow. Stamped on the chassis was the date of manufacture: May 3, 1967.


Diagnosing the dead-radio problem took about 30 seconds. I began to trace the power supply starting at the power cord, and found that the cord was defective. The plug end had an internal break, possibly caused by knocking the radio off a table, or some other accident that yanked the plug sideways in the wall socket.

The hidden break was invisible to the naked eye, but evident when I connected an ohmmeter to each wire and flexed the plug blades back and forth. With such an intermittent break, the radio could mysteriously quit working—or start working again—depending on how you happened to stress the broken plug.

After I replaced the cord, the radio played like new:

From: Phil Nelson
Date: April 18, 2020
Subject: RE: Hello! (and help)
To: Sarah Koenig

Your radio is fixed! The problem was very simple -- a broken
power cord. Here’s a 30-second video that shows it playing:

It sounds terrific (as good as my restored 21), so I wouldn’t
do anything else to the electronics. Cost of new cord: $3.
The little damper pillow is part of the acoustic design, so
I would recommend putting that back in. If its bag is falling
apart, just put it in a new muslin (or whatever) sack. I can
probably find something to replace the seal around the edge
of the back cover.
As for the front, I should be able to clean much of the dirt
& staining from the front grille material. That plastic
material has shrunk so there is a thin gap between the edge of
the material and the cabinet frame. I don’t know any way to 
un-shrink that stuff; heating it might even shrink it more.
Most of the wood on the cabinet isn’t bad. If not for that big
black stain, I would give the wood a light "refresh"
to even out the color and hide little scrapes, and then apply
a new coat of clear satin lacquer for protection. But you don’t
want to do that without somehow addressing the black stain.

The black stain may be mildew, often caused by leaving a wet
plant pot on top. The standard treatment for this is to bleach
it with oxalic acid. That works best when the stain is small
and not so dark.
I have never tried to bleach a stain as dark and big as this
one. If you’d like me to try, I can get some oxalic acid and
give it a whirl, but no promises. Worst case, I imagine you’ll
end up with the same stain, only not as dark.
Or, you could just say the stain is part of the radio’s history,
and leave the cabinet alone. Let me know what you’d like to do.
Either way, I’ll clean everything while I have it on the bench.


From: Sarah Koenig

Hello Phil! That’s great. I had a feeling it was something
super simple that I didn't see. I’m so glad you fixed it. 

Yes, please, I’d love it if you could clean the plastic grille
a bit (I noticed the shrinkage, too; it doesn’t bother me).
And yes to attacking the black stain on the top with the
oxalic acid. As long as you’re saying the worst that happens
is that it doesn’t work -- like it’s not going to make anything
worse -- then yes, please do give it a try.

If you have some sort of sack for the fiberglass pillow,
that’d also be great. (So long as it’s not going to heat up
and catch fire or something, right? The other guy I brought
it to said it’s maybe better not to have it in there.) 

Thank you very much. I’m so excited that the radio’s getting

Best, Sarah

From: Phil Nelson

OK, I’ll deal with the cord and grille right away, and try
to get my hands on some oxalic acid.

I checked some likely sources for oxalic acid, and -- Ha-ha,
the joke’s on me! -- discovered that the industrial products
sold out ages ago, along with every jug of Clorox on Planet Earth.

I recalled that the common household cleanser "Bar Keepers
Friend" contains oxalic acid (although in lower concentration
than the industrial products). Guess what -- everyone is sold out
of Bar Keepers Friend, too! Who knows, though, there might be a
bottle of that lurking around in some local store.
If the cabinet were made of solid wood, I could sand the stain
until I reached clear wood underneath. But if you sand thin veneer
too aggressively, you’ll sand right through it and expose the
ugly framing wood underneath.

Perhaps there is some other (available!) elixir that I can use
to lighten the stain. I’ll post a question in a wood refinishing
forum and ask for ideas.
Don’t give up yet! I’ll keep you posted.

From: Sarah Koenig

Ah! Of course. That makes all kinds of sense. But if it’s too
difficult, please don’t worry about it. I can always try to deal
with the stain  sometime in the future. Thanks so much, Phil.
I really appreciate this. 

Best, Sarah

From: Phil Nelson

So, I found some oxalic acid at a local store (amazing what you
find if you actually look) and tried that.

The first photo shows your cabinet before I applied bleach. The
second shows it after three rounds of bleaching:


The bleach works, but not as quickly as I had hoped. I wonder
if this stain is not ordinary mildew, but something else? In
any case, the stain is lightening with each application, so
I’ll mess with it a little more tomorrow.

Don’t worry that this is too much trouble. I haven’t used
this kind of bleach before, so here’s a chance to learn
something. And it’s more fun than facing the thousand overdue
household/garden chores that lurk outside my workshop door.


From: Sarah Koenig
Date: April 22, 2020

That’s great! The stain does look lighter, for sure. I love
getting these updates. 

Trivia: today, Earth Day, is my Dad’s birthday. He’s the guy
who named Earth Day, in part because it rhymed with birthday.
He was an advertising copywriter, and was asked to come up
with a name  for the movement. So -- you’ve got his pre-Earth
Day radio right there. Happy Earth Day, and thanks again. 

Best, Sarah

From: Phil Nelson

Hey, how cool that your Dad named Earth Day! I forwarded
your note to my wife, who works at a local organization called
21 Acres, which is about sustainability, supporting local food
production, and all that wonderful Earth Day stuff.

Sarah's father, Julian Koenig, was not your everyday copywriter. Among other things, he was credited with the award-winning "Think Small" ad campaign for the Volkswagen Beetle. And the Mad Men TV series afforded him an extra 15 seconds of fame. In Season 2, Episode 1 of that show, Don Draper (played by Jon Hamm) pans a fledgling copywriter's work as unoriginal, noting it "has Julian Koenig's fingerprints all over it."

From: Phil Nelson

Yesterday, I went through more bleaching rounds, and finally
hit the point of diminishing returns with your radio cabinet.
Even mixing the bleach at double strength, or heating it in
a microwave, didn’t produce the result you’d want.
I consulted a cabinetry forum where people have used oxalic
acid. The consensus seems to be that if the bleach doesn’t
work in roughly sixty seconds, it's not going to produce
dramatic results, period. We may infer that the stain was
something other than black mildew.
I attached a photo showing the cabinet in its present state.
I recommend that I go ahead and refinish it, using toning
lacquer to restore the dark brown color and topping that
with a couple of coats of clear (satin finish) lacquer for
protection. The stain will still be visible, but not as
dark and ugly as before.
BTW, yesterday I got some mileage out of your Dad’s story
when I joined a Zoom chat with some pals from a past career.
I told them I  had a little tale that reveals one of those
mysterious, unexpected connections -- in this case, a nexus
between antique radio repair in 2020 and the naming of
Earth Day in 1970.
One of them asked whether your father looked like Don Draper.
I said, Perhaps not, but he was clearly a lot smarter!

From: Sarah Koenig

That makes a lot of sense as a plan. Thank you so much for
trying! My Dad, alas, did not look like Don Draper.
He was more Groucho Marx than Jon Hamm.

I actually did a radio story about him some years ago.
If you’re bored:


Best, Sarah

From: Phil Nelson

What a wonderful photo!  Thanks for sharing, and for the
link to your radio story. Sounds like perfect listening
material while I’m fixing your Dad’s radio.

I replaced the old broken power cord. The radio plays and
sounds great.

I’ll start the cabinet refinishing tomorrow. It will
take until Saturday because one step (grain filling)
requires overnight drying.



Refinishing the cabinet wasn't difficult, but it meant starting from ground zero, since repeated applications of liquid bleach had stripped the wood, leaving open pores and a too-light color. First, I applied grain filler to fill the pores and create a smooth surface. Then I sprayed on tinted toning lacquer until the color looked the same as my own radio. Finally, I applied two coats of clear satin lacquer to protect the colored layer.

From: Phil Nelson

The cabinet refinishing is done. As expected, the black
stain is still visible, but it’s less dramatic than before
and the rest of the cabinet is more presentable.

I looked at the damper pillow again, and I’m inclined to
simply reinstall it. When I cleaned dust out of the radio
chassis, I found no fibers separated from the fiberglass
batting. It doesn’t seem to be shedding at all. Its bag
is torn, but if I face the split upward and fold things
together, I bet it will sit there safely for another 50 years.

I began to clean the grille cloth with isopropyl alcohol
and a soft brush. The residue came away brown, which is
typical of old radios (the brown grime is years worth of
cooking fumes, tobacco tar, etc.). I stopped when I noticed
that the glue under the cloth was softening. The cloth is
less grubby than before, but not perfect, I took advantage
of the softened glue to refasten the left edge of the cloth,
which was separating from the backing frame.

I gave the chassis a nice long bench test while all that
was going on. It is stable and it sounds great! These sets
are quite reliable -- my Model Twenty One is still working
perfectly with all original components -- so I expect
yours to work well for quite a while.

I can ship your radio back tomorrow. Unless you tell me
otherwise, I'll use your return address from the box.



From: Phil Nelson

Your radio is on its way! I shipped it via USPS today.
I did reinstall the damper pillow before replacing the
back cover. As a final check, I did a "Pepsi challenge"
with your radio playing next to mine on the workbench,
alternating back and forth to see whether one sounded better.
They sounded identical to me, so I figure your radio sounds
as good now as it ever did.

If it’s OK with you, I’d like to write up this project for
my website, perhaps as an addendum to my existing Model
Twenty One article.

Let me know if your package arrives safely, with the radio
in working order. I’d rather not talk about payment until
I know that you’re satisfied.
Thanks for letting me work on your set! It really has helped
to break the monotony of this dreadful lock-down time. Now
that I’ve completed something, maybe I can shift back into
productive mode, after sulking far too much during recent weeks.
Phil Nelson

From: Sarah Koenig

Hi Phil. After probably a good eight or nine years of absence,
my radio is back on my bedside table, looking spiffy and
sounding perfect. I’m so happy. Thank you, thank you, thank you.
Yes, of course feel free to write up this repair for your website. 

I hope you and your family stay well.

Best, Sarah

From: Phil Nelson

Oh, what a relief to hear that your package arrived safely.

I was disappointed that I couldn’t make the stain disappear,
but that wasn’t in the cards. Just consider it part of that
radio’s history, as the saying goes. We all collect a few
knee scrapes along the way.

Thanks for the pointer to the radio story about your father.
I laughed out loud during the part with his race-track buddy
("He doesn’t even like me that much . . . but I have a
car!"). And how appropriate that the story ended with
Ira Glass announcing an exotic new thing called a podcast,
entitled "Serial." At the close of a story about
your father’s legacy, we hear about the project that became
part of your legacy.

If you send me a check to cover the postage, that will be
plenty. The cost of materials was next to nothing: I
installed a new cord that I happened to have on hand, and
the finish was just a few spritzes from spray cans that I
already had in the shop.

In lieu of a fee, perhaps you’d be willing to send me a
snapshot of your radio back in its home environment. My
restoration articles usually end with a pic of the finished
product, but I forgot to take an "after" shot.

Anyway, the photo’s optional. I enjoyed doing this project
and chatting about it. I look forward to hearing more of
your work in the years to come. You are a gifted writer --
keep it up!



From: Sarah Koenig

You got it. I’ll take photos. (And if it’s useful, you are
welcome to use any material from our emails in your post.)
Thanks again, Phil. And take care, Sarah

From: Phil Nelson

Thanks! It may be a little while before this article appears.
First, I need to finish a long article about a project that
has been dragging on much too long.




From: Phil Nelson

Hey, I got your check for the postage, and the delightful
cartoon of your happy radio. Thanks!

Hope you & yours are surviving OK in this wearisome time.


From: Sarah Koenig
Date: May 9, 2020

Oh, good. Thanks Phil. You, too. Best, Sarah

Thus ends our little tale, and now you know the connection between Earth Day and the KLH Model Twenty One radio. Yes, it took me nearly two years to write this article, but better late than never!

Refer back to my earlier article for more technical details about this great KLH set.

©1995-2024 Philip I. Nelson, all rights reserved