1955 Granco FM-610U Tube Radio (pics)
 

Went in to a local vintage stereo shop this weekend and while digging through the back of the store, I found this Granco FM-610U Tube Radio. It was awfully dirty but no cracked and had a sticker on the bottom stating that it works, but noisy. So I took a chance on it and paid $20.00 for it. Took it home and cleaned it up in and out and gave it a polish.

The story of this company is crazy. The company was around for approx 10 or so years, but the factory burned down and management did not renew the insurance. I read that a Hot Iron was left unattended ! :cry: Shortly after, the company went bankrupt.

I was recently in touch (through email), with the daughter of the owner of Granco.
She told me that Granco design and assembly-line production made Granco the first U.S. company to produce low-cost AM-FM radios and the company would have continued to do well if Management had done the right thing. There were also Granco works in Emerson bodies.

More info here:
http://www.radiomuseum.org/dsp_herst...ompany_id=3849
http://antiqueradios.com/forums/view...27617#p1327617
http://antiqueradios.com/forums/view...27021#p1327021


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Kewl !

Blonder tongue made a similar product.. I would like to see inside this one, my blonder tongue fm tuner is so cheaply made it's amazing
It works

This radio has some nice weight to it.
Here's some inner shots

http://www.radiomuseum.org/r/granco_610.html

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I have a Sarkes-Tarzian FM radio, that's similar in design, but has the Zenith type Gated-Beam FM detector using a 12BN6 and even has a buzz control. :D
They made one for Admiral, as well. :yes:

Note that there is no variable tuning capacitor. It moves slugs through coils to tune. A spinoff of the Dumont Inductuner or the Collins PTO.

I'm amazed these FM-only radios sold at all in the 1950s. What was there to listen to on FM in most cities (let alone areas far from such cities) in those days? AM radio was still what most people listened to back then. The reception problems, if you were any distance from major cities, made it all but impractical to have any kind of FM radio until the 1970s or so. FM stations in major cities in those days either simulcast AM stations or played automated elevator music, and many of those stations went silent due to lack of advertising revenue. Most of the FM stations in Cleveland were still automated as late as the 1980s; most did not switch to live programming with DJs until the early 1990s. In fact, the last station to drop automated elevator music in 1991 was located about 60 miles outside Cleveland. That station is now operated by a large media conglomerate which has already bought up most of the FMs in the area (the rest having been swallowed up by CBS Radio), and is now playing some of the poorest excuses for music I have ever heard in my life.

I have another version of this radio which is AM/FM in a maroon cabinet. It still says "FM" at the top of the cabinet, but the raised frequency numbers are covered by a brass plate with printed markings for the frequencies of *both* bands. A lever switch on one side selects the band. Looks like the one in this listing:
http://www.ebay.com/itm/1955-GRANCO-...-/350387681360
Cute little radio, heavy as a brick, not a great DX set.

Update: found more detail about my AM/FM version:
http://nabilaagila.com/radio/

jr

These Granco radios are not the easiest to find, so I read. Considering they werent in business for too long, and sold Primarily niche FM radios. Im sure the radios needed very high sensitivity to pickup the FM stations back then !

The Granco's worked better than the earlier Zenith's and RCA's built before it. For a simple design, they drifted very little and were extremely reliable.
I used to buy every one of those radios, I could get, as they picked up the local FM stations, using just the single one foot wire, coming out of the back.

I had one of the AM/FM Grancos around 1960 and with a properly placed audio tap used it as a tuner with my first Hi Fi system. It worked great. Somebody gave me a rotator and I "made" an antenna and mounted all on the roof, maybe only 20 feet off the ground, and could pick up stations hundreds of miles away.

Update:

Brought in the radio to a local radio repair shop. They replaced a few caps.
All original tubes work. The speaker is blown, so it will need replacing.
I also painted the lettering with Krylon Gold paint. Looks better now.

If anyone has an original speaker for it, let me know.

Heres a video:

http://youtu.be/BV0rUFGKwsE

It sounds like the cone is warped and the voice coil is rubbing on the pole piece. It seems like those oval speakers were more prone to do that.
An easy, temporary fix, is to remove the chassis and while the radio is playing, press gently on the back of the cone, on both sides to see what side is causing the distortion and try to stick some cotton between the frame and the cone, to minimize the drag. You'll find out easy enough. The so-called shop you took it to, should have, at least, done that.
The speaker is rather special, as the frame is sheared off, on the bottom and the magnet housing must be, drilled and tapped, to mount it on the chassis.
Reconing is a better option. :yes:

There's a very good shop that may be able to repair the speaker for me.
Gonna see what they can do.

http://www.fabaudio.com/

One trick I've heard of is to wet the cone then let the speaker dry open end up. After it has dried it should not rub again.

Yes, that worked quite well for me on a 5" round Zenith speaker. I hope you don't need to replace the voice coil:no:

The speaker is blown (distortion)
Here's a picture of the speaker for size reference.
Gonna either fix or replace it.

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I'd change that 2uF 50V lytic.

The radio was sent out and gone over by a vintage radio service shop.
That is not the issue. The issue is the blown speaker.

BTW, At $31.00+ no way Im paying that for a cap !

http://www.ebay.com/itm/CAP-2UF-50V-...item1c3e417af0

This concept was probably derived from the Dumont Inputuner. I have three Zenith radios (K731, C845 and Royal 3000-1) that use permeability-tuned coils for FM tuning, no tuning capacitor for that band. There is a tuning cap in each radio, but it is used strictly for AM (and shortwave in the 3000-1). The sensitivity of all three sets is excellent, probably due in large part to the permeability-tuned FM front end.

BTW, I did not realize that Collins also used such tuners in their amateur gear, and I've been in ham radio over 40 years (just renewed my license for another 10-year term). Never could afford Collins gear, but I remember seeing it advertised in QST, and back when the ARRL Handbook had an advertising section way in the back of the book.

No, the "slug tuned" components shown in the excellent close-up photo by Robb are actually sleeve variable capacitors... they are indicated as capacitors on the schematic as well. On the photo you can see the two "plates" of each variable cap and the small trimmer cap soldered between them. The "slugs" increase or decrease the capacitance between the two "plates" to tune the radio. The coils in each L-C are located to the sides of each variable capacitor and are fixed in value.

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jr

Anyone know how to remove this speaker ?

I'm guessing that the two screws under the chassis by the rectifier hold the speaker. I never took mine out.

jr

That is a standard 4x6 inch speaker, although I doubt they are made any more. Still, they should be available either NOS or cannibalize.

Before you take the speaker out, try the "spritzing with water" thing -- but allow it to dry with the radio upside down. Nutty, but it's free to try.

Over on AK, there are guys that have a certain hi-fi speaker whose cones "droop" over time. The go-to fix is to rotate the speaker in the cabinet, or just turn them upside down half the time.

Chip

It's really not a common 4X6" speaker! As you can see, the bottom part of the frame is trimmed off, as part of the frame stamping process. Also, the magnet housing is drilled and tapped, probably for a 8/32 machine screw.
Try the water trick! If it doesn't work, then send it out.

or stick a piece of cotton wadding behind the cone, move around to find sweet spot.

Looking at the under chassis views, they either didn't do anything to it or they did the finest job of duplicating the original soldering job. I vote for the former.
BTW, the resistor above the left IF transformer, looks a little cooked. Also the speaker isn't blown. If it was, you wouldn't get any sound at all. All you have is a voice coil rub, due to a warped cone.

I have fixed plenty of speakers with the water trick. Get some water in a cup. Using your finger or a small brush, dampen the whole cone. Keep water out of the voice coil area. Set the radio with the cone facing UP towards the ceiling and let dry overnight. Be sure it's completely dry and try it the next day. You have nothing to lose.

Dude that cap is not worth more than $0.50, you have lots of resources in Toronto too, forget eBay. I suggest going here http://www.a1parts.com/ they have all kinds of cool stuff not on the website. I bought a bunch of loose capacitors there really cheaply. It's worth a trip to the store just to check out the massive stock of old and weird electronics as well as the new components.

Here's the cap you need http://www.a1parts.com/capxon/index.html 2.2uF 50V. $0.24 each.The radio will sound like crap if that cap is dried up, but yes it could also be the speaker.

Why not disconnect one lead to the speaker and try to hook it up to something else (like a stereo at low volume), just to double check that the speaker really is bad, before getting it all wet.

I'm going to try that trick! I have a Zenith 845 series, with the 8" bass and midrange speaker. The voice coil has a real slight drag, only heard at low volume.
I think it should be allowed to air dry and not force dried, as by a hair dryer or such.

Im going to try this.

thanks

Yes, let it dry slowly, overnight and into the next day, even. What happens is that over the years the cone sags by gravity and by absorbing moisture. When it's dampened again, it becomes pliable, and the spider, which is not made of paper but of a treated cloth, and is not hydroscopic, can now pull the cone back into center where it will stay when the paper dries out again.

If this doesn't work, the next step is to remove any felt center cover disk, loosen the glue joint between the outer edge of the spider and the speaker frame with acetone, and use three or four thin paper or business card spacers between the voice coil and the center pole piece. Then the spider is reglued to the speaker frame.

Should have said at the first, you can tell if it's a voice coil rub, with radio off gently grasp cone 180 degrees apart with finger and thumb and move slightly in and out: listen for scratching to indicate a rubbing voice coil which should respond to the wet cone treatment.