Posts Tagged ‘restoration’

1931 Westinghouse WR-8 Columaire Antique Radio Repair

April 14, 2014 Leave a comment

I recently got to work on another beautifully reconditioned Westinghouse WR-8 Columaire radio all the way from Bellingham. It was originally in for service with the SPARK Museum, but the repair technician reportedly suffered some health complications and was unable to complete the job so it came down to Seattle to finish it off. I’d previously worked on one of these back in 2013, but this one was in a bit better shape – although it took a long road to get there!

At some point in the past, the radio was badly damaged by an errant candle placed on top which must have fallen over and badly burned the top half of the radio. Afterwards, it was placed in a basement for many years and forgotten about, collecting moisture damage and dust along the way until being brought back out.

The owners spent a lot of time on the cabinet:

and reconing the speaker:

Then it was into the shop for the detailed electrical repairs!

All of the tubes in this radio tested brand new, and all the transformers and coils checked out, so it should be a pretty straightforward repair. Overwhelmingly, the resistors tested in spec also, only a few were slated for replacement. It’s been worked on before at one point, too:

An interstage transformer, normally potted in a top can, was replaced with an open-frame transformer from the late ’30s or ’40s, mounted under the chassis.

This model could be used with a phonograph or a remote control, although neither option was fitted on this model.

I began by mounting new terminal strips under the chassis, soldering them to the lugs on the old capacitor pack.

I took a slightly different approach for the other capacitor pack, using the existing phenolic board as the terminal strip after cutting off the pack capacitor.

For a size comparison, here’s a third capacitor pack containing only a single capacitor – and on top, its replacement, and a quarter for scale.

The owner requested something to make it easier to reset the clock when the time came: Molex connectors! I use 600V connectors with individual connections.

Not the prettiest, but it’ll work. The wire insulation was nicked in a few places, so I reinforced those areas with electrical tape.

Time to fire it up and test—loud and clear! I peaked up the alignment carefully and let it burn in for a while. The lead routing ultimately needed to be tweaked a little bit as there was some interference, but it was easily corrected.

After refitting both chassis and the speaker back into the cabinet, this Westinghouse was ready to go home and make warm, rich, beautiful music for many years to come.

What a beautiful piece! You’d never know how far it had to come to get to this shape. Bringing it back to life so nicely was a joint effort – without the owner’s dedication to the cosmetics of the cabinet, it would never have made it to the electrical stage.

If you need your antique radio repaired, Rain City Audio can help!




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1946 Zenith 6-D-029 Consoltone Antique Radio Repair

April 7, 2014 1 comment

A local client just brought in a very interesting Zenith tabletop radio from just after WW2, the 1946 Zenith 6-D-029 Consoltone mantle radio. This is one of the iconic “boomerang” dials Zenith produced for a couple of years after the war. A variety of sets were made with similar styling; in this case the 6-D-029 is a 6-tube AC/DC radio with a combination of octals and loctal tubes.

This radio was repaired in the ’90s by a radio shop in Portland, OR but came to me in non-working condition. That’s not unreasonable for a radio to need another round of service after 20 years, and it looks like they did good work last time.

Checking out the tubes, other than one which was conveniently labeled (and testing confirmed) “weak”, they all had good filaments and good emissions. Something else was clearly the problem. Given the set’s owners don’t own a tube tester, the tube labeled “weak” must have been from the last time the radio was serviced; this one was the RF amplifier front-end tube.

It’s been pretty well cared for – the cabinet is in solid shape and there’s only a tiny amount of dust inside. Underneath, however…

There are several things going on here. Number one is somewhat obvious: something has released some smoke inside. In addition to that, the electrolytics used in this repair were different ages. There’s the blue CDE dual-section capacitor, and a Jamicon 33uF 450V capacitor hooked up as the second filter. Time to start pulling parts.

That Jamicon capacitor is visibly bulging from one side, and testing confirms it’s definitely dead. Of the CDE dual cap, one section was badly out of spec, and the other section tested open as well.

One of the ceramic disc capacitors blew itself apart – rather violently damaging a mylar capacitor near-by and generally making a mess of things. I replaced all of the same model of capacitor with new 630V film capacitors just to be safe.

After replacing the components it was time for the first power-up. No smoke! But, no sound either. Checking around on the voltages, something wasn’t quite right. B+ on the output tube was about 50% high, and there was no voltage on the screens of any tube.

Careful inspection and wire tracing got to the root of the problem: the wire between two tie points, supplying high voltage to the screens of the output tubes and the plate and screens of the RF and IF tubes, had broken at some point – likely from 68 years of metal fatigue. This was likely the root cause of the original failure: the ceramic disc capacitors were rated at 100V. With 4/6 tubes not conducting, the power supply was delivering over 160V when the nominal operating B+ was about 100V under load. This is well over the rating of those ceramic capacitors and could have caused the violent failure which took the radio out of service.

That’s more like it! A jumper confirms the issues has been located. The new capacitors are rated 630V, so should have no trouble with voltage spikes.

I soldered a 2″ segment of wire to make the connection permanently.

With that repair made, the radio fired up loud and clear!

Time to adjust the alignment a bit:

Then finally, back into the cabinet and ready to go home.

With all new film and electrolytic capacitors, and a replacement tube, this Zenith table radio is going to last a very long time before it needs to be serviced again and sound great the whole time.

If you need your antique radio repaired, Rain City Audio can help.

1940 Philco 40-185XF Antique Radio Restoration

April 2, 2014 Leave a comment

I had the privilege of working on a very well preserved Philco 40-185XF recently. These are top performing pre-war sets featuring 8 tubes, an RF amplifier front-end and push-pull audio output into a 12″ speaker. Definitely worth fixing up! This radio had been its owner’s family for years – first in his grandparent’s home, then with his parents, before it passed on to him. After serving as a conversation piece for many years, it was time to get it going again.

This model had been sitting silently since the 1970s and was ready to come back to life. It came to me for a complete overhaul, including testing all the tubes to replace as needed, re-stringing the dial, replacing hardened rubber mounts and eroded pushbuttons, and a precision alignment.

The underside is nicely laid out and pretty easy to work on. There’s a few capacitors which are buried, but most are easily accessible. The output transformer, top left, is mounted under the chassis instead of on the speaker as was more common on earlier sets.

Component replacement was initially pretty straightforward. The preset assembly was held in by two screws and had plenty of slack to fold it up and out of the way to allow easy access to the components beneath it. There were several small capacitors and an electrolytic can mounted under the pushbutton assembly.

The power cord was in dire need of replacement, so it received a new polarized plug and new X1Y2-rated safety capacitors on a newly mounted terminal strip.

With component replacement complete, it was time for a first power-up and a test signal. All seemed to be good at first for a bit…but then the radio sputtered a bit and cut out entirely – then some faint smoke started to appear! Bad, bad sign. I killed the power quickly to avoid damaging anything and carefully inspected the fault.

On this schematic snip, the resistor circled in red was the one which was overheating and smoking. This resistor feeds the high voltage to the front-end of the radio; overheating means excess current drawn. I pulled those tubes, but it continued to smoke, so further investigation was necessary. First, I replaced that resistor with a new one which hadn’t been heat-damaged.

It’s a bit faint, but the insulation had cracked off the wires leading into the IF can and were shorting to the chassis. That’d be the problem! Time to pull the IF can:

Some wires were cloth and some rubber-coated; some of the rubber coated ones were fine, and some were brittle and cracking. I sleeved the damaged wires, then reinstalled the transformer in the can and mounted it back up. One problem solved! The short circuit was fixed, but there was still no audio output – even when injecting directly into the audio amplifier circuit.

There were some clicks when I’d touch certain resistors with a probe. The resistors had overwhelmingly tested within tolerance so most were left original, but something happened along the way. I pulled the suspect resistors to replace, and examined the old one:

It’s tough to see – but the body of the resistor is cracked! This was a new problem. What happened is: carbon composition resistors absorb moisture from the atmosphere over time. In this case, the radio is 74 years old, and 44 of those years it sat without being played. Resistors also dissipate heat when they’re operating. This combination caused the absorbed moisture to expand and escape by cracking the body of the resistor and causing intermittent opens. Not good for performance! I replaced nearly all the remaining resistors at this point.

The replacements are 1% tolerance precision metal film resistors which should last for a very long time, and don’t absorb moisture the way carbon resistors do. Now, I was able to get audio, but no radio reception. Testing the front-end verified the radio was operating, but it wasn’t tuning a signal. Time to investigate the band switch – which, surprise, was badly gunked up! The mechanism wasn’t allowing the tuning capacitor to engage, and all the contacts were badly corroded which was killing the signal.

You can see how much gunk and oxidation had caked up onto the switch contacts – on the left, not processed; on the right, cleaned and scrubbed.

With that, the radio roared to life and picked up stations loud and clear across the dial! There were a lot of problems, but they were all able to be corrected. I peaked up the alignment using my standard signal generator, then did final inspection checks.

Finally, it was ready for the trip home! It sounded even better installed back in the cabinet.

The owners had the cabinet refinished while the radio was in the shop – it’s a perfect pairing! New pushbuttons and new rubber mounts and the radio is nearly as nice as they day it left the showroom floor.

This family heirloom is back in running shape and is going to serve faithfully for many years to come as a beautiful piece of functional furniture. Just look at it!

If you need your antique or vintage radio repaired in the Seattle area, contact Rain City Audio.

Bose Equalizers on eBay Need Service Too: A Photo Comparison

March 31, 2014 Leave a comment

You’ve had your Bose 901 Series I or Series II speakers in storage for a few years, the Active Equalizer packed away with them and now you’ve pulled them out to set up your vintage system once again. Great – keep going! Only there’s a problem: you only get buzzing or low and distorted output from one or both channels. It worked fine the last time you plugged it in!

Your first thought: go grab a working one on eBay!

And here’s the problem. One of these is a working equalizer; one is dead in need of a major overhaul. Can you tell which?

I do believe this equalizer works – and if you don’t have one, that’s a fair price for a known-good one. But even still, it’s going to need an overhaul sooner than later. It’s made of the same components, which are now more than 40 years old. If you do already have a Bose 901 Series I or Series II Active Equalizer, you can have it rebuilt and leave a complete replacement for someone who needs to replace one that’s gone missing.

Bose Active Equalizer Repair

1938 Zenith 5-S-220 eBay Tune-Up Special

March 26, 2014 Leave a comment

I’ve had the opportunity to work on several very nice Zenith radios lately and this one is especially interesting. It’s the Zenith 5-S-220 Cube. This is the first time I’ve seen one of these in person, they’re somewhat uncommon. Electrically, it’s a nice 5-tube radio with a broadcast and shortwave band, and the cabinet is very compact with the speaker firing vertically through the top of the cabinet. The black dial in the face is very easy to fine-tune.

It was sold as in running condition, and it worked okay on the standard broadcast setting, but with the switch on the Treble Cut tone setting the set picked up bad warbling low-frequency interference, called motor-boating. It also just didn’t sound that good, and Zenith radios are known for their excellent tone even from their small radios.

The chassis is supported on small risers to replace compressed paper spacers. It’s fairly cramped in there,but the chassis slides out easily when the spacers are pulled out and the speaker socket makes service easy.

Underneath, the solder joints were all very good in fact. Mostly original resistors retained.I tested the resistors and many were well outside of their specifications; there were several other problems as well.

The previous service had replaced all but one of the original vintage tubular capacitors that are candidates for replacement in any vintage radio.

The resistors were all original. This frequently isn’t a problem – vintage resistors can still test within tolerance, and if so, don’t need to be replaced – but these were almost all bad. I found some which measured as much as 250% of their marked values. The radio actually played like this, it just goes to show you how robust these tube circuits were. They’d tolerate a lot of abuse and still sound passable.

I replaced the vintage capacitor and many resistors but the motor-boating persisted. Throughout all of this, the volume is lower than I’d expect, too. I went about replacing the Micamold capacitors which can frequently go leaky and exhibit odd symptoms. These are in fact paper capacitors in a molded package – not true mica capacitors which tend to hold up well even today.

While poking around at those connections, an entire solder blob moved – the ground connection had broken off entirely:

I replaced this one with a true mica capacitor and a solid ground connection. A few tweaks to the alignment later, the motor boating was gone, but the low volume persisted. Even on the normal position it was still lower than it should have been. I examined the tube line-up versus the schematic. This radio had a 6V6GT tube installed when the radio was designed for a 6F6G tube.

In general, those tubes are “fairly” close and you can often plug them into each other’s sockets. The radio will play, but with more distortion and lower volume, as they do have distinct design characteristics. The mismatch will get you significantly lower volume as a result, too. I had a 6F6G which tested like new in stock and made the exchange:

With this, the radio roared to life with perfect volume. It sounds absolutely fantastic, especially for such a small cabinet and speaker. It also goes to show: be cautious buying radios on eBay. They might even work, but often may have hidden problems like this. It’s worth it to ask for under-chassis photos to check the amount of work that was done.

With the feedback problem corrected, I performed a precision alignment and the dial tracks in perfectly.

Overall, to bring this radio up to standard I replaced many resistors, replaced several capacitors with modern technologies, repaired a broken ground connection for the capacitors, aligned the radio using a standard signal generator,  and replaced a wrong tube. Now it looks as good as it sounds – practically brand new.

Antique and vintage radio inspections and repairs.

Other radios

Craigslist and eBay Antique Radios – Be Careful!

March 19, 2014 2 comments

It’s not uncommon to run across antique or vintage radios on Craigslist, eBay and other sales site which are advertised as “working”, “repaired” or “restored”. Many times these are in fact professionally reconditioned items – just like you read about here – but occasionally, there are some critical hidden problems to look out for. Let’s take a look at an underside photo which was included in the for sale posting: Echophone-2

Not too bad! It looks like there’s some new capacitors carefully installed – but there’s a problem. Can you spot it?


Again, with a hint this time! Several original paper capacitors look to be installed in the radio. It’s even believable they might work – by and large they’ll be well past their service lifetime, but through dumb luck you do occasionally find vintage capacitors which are still technically operational. Even if one is working now, though, they are universally all completely unsafe for operation for any length of time. Old vintage capacitors like these can spontaneously fail and short out, which can damage the radio or even start a fire! A repair like this is not in compliance with the best practices for antique radio repair, and I wouldn’t let one out of my shop in such a condition, that’s for sure!

If you’re buying an antique radio or vintage radio and have the opportunity, ask for photos of the underside of the chassis or ask to inspect it personally and check for old parts. If you’re having your old radio serviced, make sure to choose a reputable repair shop or service technician who will follow best practices and replace all components which are subject to spontaneous failure – not just the ones which are bad “right now”. Your radio – and maybe your home – depend on it! If you need your antique radio repaired in Seattle, the Greater Seattle Area, or shipped from anywhere in the country – I can help!

Bose 901 Series I Active Equalizer #30924 Repaired

March 18, 2014 Leave a comment

I recently got to work on another Bose 901 Series I Active Equalizer, Serial #30924, which needed some service. It’s coming from the original owner who purchased them new in 1970, they went into storage about 10 years ago when the equalizer started producing uneven output in each channel and cutting in and out. This particular one was in for the full works, including a few upgrades, to bring it back into active service.

In addition to replacing the worn out capacitors and drifting resistors, this equalizer’s owner has requested I bring it up to modern spec with a few upgrades: audiophile grade film output capacitors to improve clarity and detail, and gold-plated RCA jacks to accommodate today’s thicker, more heavily shielded RCA cables. All of the solder joints were soldered using 4% silver solder which lowers joint resistance even further.

This equalizer sounds absolutely fantastic when hooked up to my test system. The color and clarity of the music really comes through, especially with the upgraded output capacitors. Fully recondition, this equalizer is going to sound beautiful for many years to come.

If you need your Bose 901 Active Equalizer repaired, I can help.

1945 Westinghouse Little Jewel “Refrigerator” H-126 Radio Repair

February 18, 2014 Leave a comment

A local client brought me a radio which was in the family for many years, a cute little “fridge radio” made by Westinghouse from 1945-1947. The same year Westinghouse released this new model of home refrigerator, they also released this Little Jewel radio in the same style as a companion. Many examples of this radio found their way into homes and kitchens over the years and are a great little collectible from the post-war era.

This little radio is a 6-tube AC/DC radio with a series-string tube line-up, 12SK7 12SA7 12SF7 12SJ7 35L6 35Z5. It has an integral tuned loop antenna and an RF Amplifier for great performance.

They sure packed it into here, too. The radio is held in place by two chassis bolts, one in each side and a rod which stabilizes it in place.

The dial scale has badly warped with age, but the grille cloth is nicely intact.

This radio’s owner mentioned that it had been playing but recently cut out. No surprise why – the original parts under the chassis looked to be in pretty bad shape!

Melted, leaking and blown capacitors will cause all sorts of issues – no wonder it wasn’t running like it used to! This radio was pretty cramped underneath the chassis, but there was enough room to install both electrolytic filter capacitors and the cathode bypass capacitor on the output tube under the chassis instead of needing to re-stuff the can on top.

I had a reproduction dial scale made up to replace the warped original, and replaced some tubes which were testing weak.

Finally, it was time to test it out and tweak the alignment trimmers, then back together! It sounds a lot better than I’d expect with such a small radio – the case makes an interesting vented enclosure. On 880 KIXI, you can really hear the low notes, and the vent on the top seems to serve as a port for the speaker.

After being refurbished electrically, this radio is going to perform beautifully for many years. It’s got a rich tone and great audio clarity even more than you might think from such a small speaker.

If you need your antique radio repaired, I can help.

1962 Zenith MK2670 Classic Tube Hi-Fi Console Stereo Repaired

February 15, 2014 Leave a comment

I recently got to work on something a little bit different – a tube hi-fi stereo console! This particular one, a 1962 Zenith MK2670, was a very high-end unit back in its day. It’s a dual-chassis unit with 19 tubes total, using the 12K25 stereophonic FM tuner and 7K31 stereo amplifier chassis with EL84 outputs. All housed in a beautiful mid-century modern cabinet with built-in stereo speakers featuring 12″ woofers and mid- and high-end compression drivers and horns.

With 19 total tubes, this model features hi-fi integrated speakers with high-efficiency 12″ woofers and mid and tweeter horns, push-pull EL84 output tubes for each channel, and built-in FM Stereo Multiplex decoding for true stereo hi-fi reproduction.

This hi-fi’s owner reported it was working well for several years but started to go downhill shortly before she got in touch to have it fixed. It was taking longer and longer to warm up and sounding more and more distorted, no longer delivering the rich warm sound of a classic hi-fi console. It was good she got in touch – waiting any longer could have led to catastrophic consequences such as component failure or even a fire. I visited her home to test the tubes and pull the chassis, then it was back to my shop for repairs. And what a job it was!

This unit had been serviced a couple of times in its life – there were some ’70s era film capacitors installed, and some of the output tubes had been replaced. Most of the tubes were original Zenith fittings and tested strong, though, so very little needed to be replaced. Since it came into the shop in working condition, too, it made the diagnostic process much easier!

The amplifier circuit is a bit different than most I’ve seen. The negative phase of the output transformers was connected to chassis, and there were two positive phased taps each connected to half of the speakers. It’s an odd arrangement, certainly, which would have let Zenith use woofers of different impedance then the mid/tweeter network without an expensive and complicated impedance matching network. Underneath, though, it’s pretty easy to work on:

Right away there’s some visible damage. This molded ceramic capacitor blew a piece of the ceramic clean off from overheating. It’s unlikely it was doing much of its job at this point. Despite a nice ceramic body and epoxy sealed ends, it’s still an acid-paper/foil capacitor inside subject to failure, and fail it did.

Many of these early disc capacitors were failing as well.

I tested and replaced resistors as necessary, and capacitors. Here’s an in-progress shot showing partial replacement complete. Even the resistors I did remove were very close to spec – Zenith clearly used high quality resistors in this hi-fi. All were shiny with intact bodies and paint, and none had the woody, chalky appearance of a tired carbon resistor.

With the amplifier chassis sorted, it was time to move onto the tuner. It’s nicely shielded on the bottom.

And there’s a lot going on inside.

This radio was build very, very densely and in layers. It’s also a modern hi-fi instrument sensitive to wiring changes, so I had to work without disturbing most of the arrangements. Fortunately, Zenith specified high quality carbon film resistors and they were overwhelmingly within tolerance, so it was just a straightforward capacitor replacement.

Even film capacitors are much different these days. The ’70s 0.47uF 400V capacitor, top, was replaced with a 0.47 uF 630V capacitor about 1/4 the size. Working with a needle-nose pliers in each hand, I was able to thread capacitors into the proper location under component networks without disturbing the top layer.

Now it was time for a power-up test. This particular radio uses an odd multi-tapped output transformer arrangement with drivers hooked up to both taps in the cabinet, so I ended up hooking up 4 distinct speakers for testing.

It fired right up and sounded great! There were a few minor issues to resolve, though. For one, there was a bad volume-invariant hum on the AM band only. This was due to a small short which was corrected. The volume controls were behaving pretty erratically, though, which took some investigation.

The unexpected behavior turned out to be due to a control scheme I hadn’t run into before. The “balance” control isn’t an actual fader; instead, the volume controls for the left and right channel are ganged together with a friction clutch. Turning the outer ring turns both together – but turning the inner ring adjusts the friction clutch allowing one to be turned independently to achieve the left-right effect. At the new set point, then, the outer ring will turn both volume controls together to adjust the loudness equally after the fade is applied. It wasn’t a popular control scheme, being replaced after a couple of years, because many consumers found it to be annoying and counter-intuitive.

After understanding how it worked, however, it turns out that it wasn’t gummed up, it was actually working properly. So, on to the next steps! Adjusting the bias on the channels:

RF and IF Alignment:

Lots of parts came out of this one!

This radio is going to continue to serve faithfully for many years, pumping out a warm and rich hi-fi sound and be a beautiful family heirloom to pass on. They just don’t build them like they used to!

If you need your antique radio repaired, I can help.

1948 Motorola 99-FM21 Console Radio Back to Life

December 23, 2013 Leave a comment

I recently had the chance to work on this beautiful Motorola 99-FM21 from 1948, currently owned by the granddaughter of its original owner. It’s been in the family since its purchase new in 1948 and was lovingly cared for the entire time, even after it was no longer in active operation. It really showed, too.

This is a post-WW2 radio when very few radios contained any shortwave bands. This Motorola has the AM Broadcast Band, and the newly developed FM Broadcast Band from 88-108 MHz. That’s right – you can pick up modern radio stations with this tuner. It has a pair of 6V6 tubes for the output (although its bass response is limited due to an undersized output transformer) and a treble roll-off tone control.

The radio looks like it had been serviced one or two times in the past. Most parts were original, but two capacitors looked to have been replaced in the ’50s.

Here’s that small output transformer. To give you an idea of size, it’s a little bigger than two stacked boxes of matches, like a restaurant might give out. A similar hi-fi amp, also driven by a similar pair of 6V6 output tubes, uses a transformer about the size my fist in the same circuit position. The amount of iron in a transformer is directly correlated with its frequency response, so Motorola seems to have cut a corner by fitting this particular transformer. It sounds good, but doesn’t have quite the bass response that’s possible.

This radio’s owner requested the ’50s capacitors be replaced with period units, and the can capacitors restuffed and the shells retained. Not many elect for that additional service as it’s quite time-consuming to perform, but in this case it’s a great choice with the radio being in the same family for so many years. I started with labeled clip-leads in place of each replaced unit to keep the circuit straight. With the schematic to double-check, this ensures error-free service.

Restuffing capacitors involved heating them to melt off the wax, then pulling on the leads until the body of the capacitor was removed. I’d then ream the cylinder, add a new capacitor, seal with polymer clay and dip in wax, then replace in the radio. I found two period-correct capacitors to replace the two ’50s units, as well.

Capacitor re-installation was pretty straightforward:

I also used similar sized electrolytic replacement capacitors which look similar to how a period repair would have been performed. It’s useful to have a bag of donor parts around to provide shells for restuffing.

At this point, I hooked up my phone as a test source and it played loud and clear through the phono input. AM reception was okay, and FM was quite poor, however. It was time to do some further testing.

This radio is one of the first to use integrated couplets, blocks of several components in a single package. In this case, the component in question is a 47K 1/2W resistor paired with two 50pF capacitors. The resistor is reading 73.9K Ohms, which is well outside of its tolerance. This one was replaced with a similar visual appearance carbon composition resistor from IRC.

I replaced quite a few more resistors, and attempted an alignment. First, I tried using the triggered oscilloscope and sweep generator, which even required building some of my own test leads:

Unfortunately, my sweep generator’s FM options are geared towards more modern equipment which deals in whole-number modulation percentages; the Motorola wanted deviations around 2.2% and 1.4% which I couldn’t provide. So I went with the FM Alignment with AM Generator option, using my laboratory signal generator the Leader 3216. The procedure was a rather lengthy one, involving de-tuning the discriminator coil secondary to cause it to respond to AM signals, then tweaking other adjustments for peaks.

After adjusting the IF transformers in order and the RF trimmer for dial tracking, I re-peaked the discriminator primary using an insulated driver to eliminate the AM noise. The FM discriminator is supposed to be only sensitive to frequency deviation; a no-deviation signal (like an AM signal) should produce no sound at all. It was a very touchy alignment, taking about a half an hour of the tiniest of adjustments to null the signal. The curve had a very slope and it was incredibly difficult to peak – similar to the discriminator in the GE F-135, but even more precise because of the much higher frequency (10.7 MHz vs. 455 KHz).

Finally, however, it did peak up and I attached a 300 Ohm twin-lead dipole. The FM antenna has a known impedance, while the AM is a flat-board loop with a terminal for an optional external longwire antenna.

After this alignment I was able to pick up stations across the dial loud and clear on AM and FM, and the phono input performed perfectly. At this point I let it play for several hours hooked to a bench speaker as a burn-in test, then arranged with the owner to return the radio and test it out. Sadly, her home is on the declining edge of a valley which offers exceptionally poor radio reception and there’s nearly nothing to be heard. Where I received nearly all AM stations and many FM stations on the same equipment, there was only a few faint broadcast stations to be heard. We ended up attaching an amplified TV/FM antenna with a 75 ohm output to a 75:300 balun and attaching that to the radio, which vastly improved the FM band – although on some of the strongest local FM broadcasts at that point, now we were driving the front-end of the radio into distortion. So clearly, this wasn’t a great location for radio. However it sounds phenomenal on period music and is going to serve for many years to come.

This is a beautiful cabinet in original condition and with reconditioned electrics is going to be a great conversation piece, keepsake and music player for many years to come.

If you’re in the Seattle or Puget Sound area, I can help with your antique radio. Ask me how!


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