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 Post subject: RADIOLA FH Horn speaker base assembly
PostPosted: Jan Fri 06, 2017 8:48 am 
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Has anyone ever disassembled the RCA Radiola FH horn speaker base?
The driver unscrews but how is the rest of the driver mounting assembly attached to the stamped steel base?
Pressed in place? Screw together- horn mount and driver adapter?

I'm servicing a somewhat ratty FH horn and I'd rather not break anything on this seldom seen model.

All for now!

Many thanks in advance.

Rob


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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Jan Fri 06, 2017 2:23 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Bossier City, Louisiana
There should be a cover on the bottom. Once cover is removed the driver should be visible. The driver should simply unscrew from inside the base. The horn is secured to the base with a brass knurled knob which allows one to turn and reposition the horn separate of the base.

You might post a picture. It is possible your horn has been modified??

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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Jan Fri 06, 2017 4:48 pm 
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Howdy Dave-

Thanks for your help with my model FH horn speaker.

The horn's complete and unmolested. Actually it's in pretty good shape but it's dirty. That's no problem to fix.
The kicker is it sat in a damp environment-- by the looks of it very likely a barn or an old garage for twenty or thirty years before I acquired it.

Anyway the dampness started corrosion build-up on the horn driver and its associated assembly. The driver's got continuity but it's dirty. Lucky the corrosion didn't get to it.

The driver screws onto -- for lack of a better term-- what might be a cast aluminum vestibule that is in turn affixed to the apex of the conical base.

My quandary is how is the aluminum "vestibule" mounted to the base? I'm starting to think that the part where the thumb screw is-- functions as a nut that threads onto what I'm calling the "vestibule" that's on the inside of the conical base. This in turn sandwiches the apex of the steel base to make a sturdy air tight mount for the driver on the bottom and the horn on the top.

Since pix say a thousand words-- I'll attempt to snap a few pix of what I'm talking about.

The FH will be a permanent part of my antique and vintage radio collection.

All for now!

Regards,

Rob


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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Jan Sat 07, 2017 6:29 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Bossier City, Louisiana
Evening Rob,

I guess I never disassembled the horn to that extent! I did not even realize it came apart to that extent! Sorry I cannot be of help!

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http://pages.suddenlink.net/davesradios/


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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Jan Sat 07, 2017 5:47 pm 
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Joined: Jan Mon 19, 2015 9:07 am
Posts: 11
Howdy Dave-

It looks like RCA/Westinghouse actually molded the top part of the FH horn driver support right into the stamped steel conical base.
I sandblasted the cast "vestibule" and the "crown" where the horn mounts in place. Used walnut shells as a blast medium. Removed the corrosion w/o damaging the metal. I can find no "interface" lines or any sign that a screw-together or press-together assembly exists. The manufacture of the FH must have been a costly undertaking if the steel base was stamped then fixtured in a mold set up and then molten metal (it looks like aluminum) poured in. The base assembly was then machined and the base and cast fixture of course painted. After the walnut shell blasting and the corrosion was gone things are not in dire shape. The base will need to be repainted.

I looked at your website. Very nice collection of radios and I am impressed with your car. I find it amazing that a car can stay in such good shape over these many years.

Thanks again for your help with the FH.

Regards,

Rob


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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Mar Sun 12, 2017 6:43 pm 
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A bit late to the party here but.... I recently restored an FH Horn: viewtopic.php?f=7&t=306685 and was thinking the aluminum piece was pressed in. Just seems like the logical way to do it.

There are couple of things I'm still curious about though. How did you get a hold of the driver to unscrew it? Mine seems to be locked in place. I tried twisting the driver cover (with some leverage) but it just rotated past the stop "bumps" and stretched the cover out over them. How did you get yours out?

I'm also curious about using aluminum at the top. I see the driver mechanism is surrounded my non-magnetic material (grass or aluminum) and wondering what's the electrical theory behind that. Probably a question for the experts... :-)

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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Mar Sun 12, 2017 11:05 pm 
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Howdy Steve-

You might be right-- that the aluminum horn "nozzle/nose/neck" receptacle at the apex of the base may very well be pressed in place but I am skeptical.. The base of the FH is really just desk fan technology of the era. I believe that the base is "deep drawn" kind of like a cooking pot. My guess is that the top part is not really aluminum but an alloy of some sort-- maybe even "clean" pot metal. If I knew more about metallurgy I'd snip off a little piece of the material and assay it.

The FH horn was produced in 1923 and for only a short while-- maybe a year. RCA may have sold the FH into 1925 but certainly no new production by then as the UZ-1320 came along and some time later the UZ-1325 which superseded both the FH and the '1320. RCA sold a peck-load of UZ-1325's. Anyway by measuring the neck of the steel base and the size of the area where the horn driver mounts makes it unlikely the part was pressed in place. Also there's not much to retain the softer metal into the harder steel base. Press fit might be plausible if the top piece was cast iron because in a "press-fit" there has to be elastic tension to retain the parts. My guess is it was cast in place since very likely that top piece is made of zinc or some low melting point amalgam-- so Westinghouse (designer/maker of the FH horn) probably utilized a steel mold that could be re-used. The part was then machined in one or two simple steps. Then the base was painted with a thick enamel coat and baked. But this is just a wild guess. I'm not going to mess with my horn base to see how it was made. Doing so would likely destroy the assembly. An antique fan collector might be able to shed more light on the production technique used here if you know any serious antique fan collectors..

My FH horn driver may have been a refit driver-- as it is labeled RCA FS Victrola attachment style 365207. The driver steel cover is a "bayonet" style fit. Essentially a partial turn (maybe five degrees) and pull affair.

The driver assembly unscrewed from the base w/o a hitch-- I used a little heat very carefully applied an adjustable wrench to grip the magnet and very-very gingerly applied counter clock-wise pressure whereupon the driver unscrewed.

The FS Victrola attachment is a "balanced" magnet set-up. Two sets of electromagnets counteract magnetic bias force set up by the driver magnet to see-saw a steel plate. The plate is attached to an aluminum diaphragm via a threaded connecting rod.

The base on my FH is rather ratty--because of where the horn spent the last fifty years. I got a new FH decal from the same place you did. I will mix custom paint-- as the base was NOT painted black but a dark-dark near black brown color. It also was not originally "mega-glossy" but more of a semi-gloss finish.

You'll have give me a better description of what you're talking about concerning the driver of your FH horn.

Regards,
Vollumscope


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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Mar Mon 13, 2017 12:23 am 
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Vollumscope wrote:
Howdy Steve-

Howdy Vollumscope...

Yes, I understand the FH is pretty rare. :-) The top part could be something other than aluminum but whatever it is it's not magnetic. I haven't seen the wall thickness where it penetrates the base so hadn't thought of that. Maybe it was pressed in and then machined afterwards? I know in engines they put steel sleeves in aluminum blocks so it made sense that they could put an aluminum sleeve inside steel.

Anyway.. my driver is a Westinghouse and I'm pretty sure it's original from the little I've found on the net:
Image

I used a home-made "strap" clamp, sort of like an engine oil filter remover, to clamp on the cover and twist but the cover squeezed past the bayonet stops. With the cover off, I couldn't get a grip on the cast part of the driver and was afraid to twist on the magnet for fear of breaking it. Didn't try heat. Maybe that's the key. Not a big deal, I just restored the outside and called it good.

Ironically, I accidentally painted mine a dark brown and didn't realize it wasn't black until I got it out in the sun. I was thinking semi-gloss too but went with the gloss after asking the question here: viewtopic.php?f=7&t=306944
I do think semi gloss might look better with the horn which is semi gloss at best. Maybe one of these days I'll put a second coat on and use semi...

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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Mar Mon 13, 2017 5:38 am 
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Howdy Steve-
BLAST! I disconnected from the web and lost my last reply. ARRRGH!
One more time!

OK I'm pretty sure your driver is original to the horn.

Did you snap a pix of the driver itself by any chance?


My FH sat in a barn or a garage for fifty years. It was very dirty but intact. It didn't look like anyone messed with it.
It also must have sat in a puddle of water for a while.
I'm still restoring the entire horn speaker. Lucky the miller rubber horn part is OK w/no splits or cracks.

The FH was made by Westinghouse Corp. One of the "parents" of RCA. It was probably designed in 1922-23 and brought to market by RCA in '23. If my historian's memory serves-- GE was supposed to supply RCA with a horn-speaker only they were having trouble producing the UZ-1320. Westinghouse came to the rescue with the FH. My guess is the FH cost a lot to produce so profit margins were slim. Not only was the driver complex but if I'm right and the driver/horn support at the top of the steel base had to be cast in place and then machined the final whammy was the horn itself. The brass nipple had to be machined. Then a perforated steel sheet was bent into a cone shape the narrow end of which was soldered into the brass nipple. Then the nipple with the steel cone was fixtured into/onto a mold and the horn molded out of rubber. The perforated steel became molded into and around the hard rubber horn body. This could not have been a simple operation-- consumer radio at the time although expensive had to be cheap to produce. No wonder that when the UZ-1320 went into production RCA quickly dropped the FH. I'm also certain that inter-corporate politics had something to do with this as well. The UZ-1325 was RCA's own horn speaker. I'm not certain who designed it and produced it but the bell was made by Miller Rubber. The UZ-1325 it was cheaper still than the UZ-1320.

I have a UZ-1325 but it's packed away at the moment. I'll have to do a little spelunking to unearth it. I know the horn has a knurled metal collar on it that screws onto the base.

The body of the driver that's in my FH is a turned aluminum round. If your driver is the same construction then you could use a pipe clamp or something like that to attempt to unscrew the driver-- it uses a conventional right hand thread. No matter I would be very careful attempting to unscrew the driver.

Aluminum was a very new metal in the 1920's-- sort of a "space age" material looking back. Twenty years earlier aluminum was a laboratory curiosity.

All for now!

Vollumscope.


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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Mar Mon 13, 2017 6:02 pm 
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Vollumscope wrote:
Did you snap a pix of the driver itself by any chance?


Yes, here's what it looks like with the cover off. Kind of hard to see but there's only about 1/8 inch between the outside of the driver and the base, so hard to get a grip. I don't really need to get it out. Was just curious how you did it.
Image

BTW - have you put your decal on yet? I found it pretty tricky as it has to be stretched a little to get it to fit on the curved base. I wound up tearing a small piece off the edge... :cry:

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Last edited by sooner on Mar Mon 13, 2017 9:19 pm, edited 1 time in total.

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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Mar Mon 13, 2017 6:58 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7149
Location: Bossier City, Louisiana
It should unscrew. Mine did.

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http://pages.suddenlink.net/davesradios/


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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Mar Tue 14, 2017 4:39 pm 
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Howdy Steve & Dave;

Your FH driver is exactly like mine. I find it interesting what happens during the course of manufacture & distribution of some of this stuff-- lost to history.
Maybe RCA banished the word WESTINGHOUSE from its products? I'll snap some pictures & post of the horn base and driver so you can see how they fit together.

My driver had to be disassembled because some insects took up residence in the horn side-- probably forty years ago. The only solution to clearing out the debris was to disassemble the driver. Also because the horn may have sat in a puddle or a very damp place for a long time the pole pieces of the electromagnets rusted trapping the armature. I have a few other tasks to complete with it as well-- so right now my driver is a basket case-- or should I say a bowl case. :)

I haven't completed the horn base either. I have the decal standing by. I am in Maine and it's still winter-- my FH base will be sand blasted before painting. It's just too cold out... until July. :D

Thanks for the heads up with the decal. I notice that it will have to adapt to a compound curve. Nothing's ever just "simple"!

All for now.
Vollumscope


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 Post subject: Re: RADIOLA FH Horn speaker base assembly
PostPosted: Mar Tue 21, 2017 1:23 am 
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Joined: Jan Mon 19, 2015 9:07 am
Posts: 11
Here are a few pix of what's under the driver in the base of the FH hornspeaker.
The first two pix are obviously of what's in the steel base.
The second two pix are of the driver disk that screws into the nipple in the base. One view is of the diaphragm side, the other view is what obviously screws into the fixture in the base.
Attachment:
RCA FH base 1.jpg
RCA FH base 1.jpg [ 129.04 KiB | Viewed 616 times ]
Attachment:
RCA FH base 2.jpg
RCA FH base 2.jpg [ 103.93 KiB | Viewed 616 times ]
Attachment:
RCA FH driver disk 2.jpg
RCA FH driver disk 2.jpg [ 78.82 KiB | Viewed 616 times ]


Attachments:
RCA FH driver disk 1.jpg
RCA FH driver disk 1.jpg [ 105.93 KiB | Viewed 616 times ]
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