Coil values for the Unelco Model 1914 Radio

[Too_Many_Tools]

The Unelco Model 1914 Radio was a simple 60's-70's muliband radio that
used different coils to change bands.

http://images.craigslist.org/3k63o33l85O65Z65S3a87c9fd7652cece1adf.jpg

http://www.antiqueradios.com/forums/viewtopic.php?p=1057824&sid=6924e5d51977bd4f787b6bc0a6754a3f

Does anyone know what the coil values were?

Thanks for any info.

[dave]

X sub L = X sub C at resonance.

[Too_Many_Tools]

On Nov 22, 8:04 am, dave <d...@dave.dave> wrote:
> Too_Many_Tools wrote:
> > The Unelco Model 1914 Radio was a simple 60's-70's muliband radio that
> > used different coils to change bands.
>
> >http://images.craigslist.org/3k63o33l85O65Z65S3a87c9fd7652cece1adf.jpg
>

> >http://www.antiqueradios.com/forums/viewtopic.php?p=1057824&sid=6924e...

>
> > Does anyone know what the coil values were?
>
> > Thanks for any info.
>
> X sub L = X sub C at resonance.

Thanks for the formula but I want the ACTUAL values.

Anyone?

[David Barts]

On Nov 22, 8:17 pm, Too_Many_Tools <too_many_to...@yahoo.com> wrote:

> Thanks for the formula but I want the ACTUAL values.

The odds of someone here having the same radio as you do are pretty
small. You're being told how to catch a fish rather than being given a
fish.

If you check back in the forum you linked to on antiqueradios.com,
there is a pretty good post giving the formula for calculating the
inductance of a coil. You can count turns and measure diameters and
calculate those figures for both coils.

Once you do that, you can then calculate the reactance of the coil at
both ends of the spectrum you know they tune. There's standard
formulas for doing this, too. I can't recall them offhand, but a quick
Google search should uncover them.

The vast majority of vintage radio sets tune by varying capacitance.
In an AC circuit (and radio frequency signals *are* AC), inductive
reactance opposes a change in current, making current lag voltage.
Capacitive reactance opposes a change in voltage, making voltage lag
current.

So if the capacitive reactance matches the inductive reactance, the
two reactances cancel each other out at a given frequency. Move away
from that frequency and they mismatch, causing the signal to be
attenuated, usually seriously so. The circuit is said to be resonant
at the frequency where the reactances match.

Now, to review: have a variable capacitor, and you can calculate the
inductive reactance at both 9.4 MHz and 17.8 MHz. Plug those values
into the capacitive reactance formula, solve for C, and you know the
capacitance range for the two circuits that the antenna and oscillator
coils are part of.

Now that you have that, you can calculate the capacitive reactance for
the endpoints of all the other bands. Then, go back to the coil
formula, keep the radius the same as that of your existing coils, and
you can calculate the number of turns on the missing coils. Find some
suitable stock for winding the replacement coils, and voíla!

(If you can't find any stock that exactly matches the radius of that
on the coils you do have, pick something as close as possible, and
plug that value into the coil formula to calculate turns.)

--
David Barts
Portland, OR

[dave]

You may have to wind your own coils.

[Too_Many_Tools]

On Nov 22, 11:44 pm, David Barts <ebaysucksdonkeydi...@gmail.com>
wrote:

Thanks David...good info.

The two coils I have for the AM broadcast band are sealed...so one
cannot see how they are constructed without destroying them.

I have yet to bug them out...I am assuming a simple coil that can be
measured for inductance.

But would still like to hear of the other values for the other
coils...it is alot simpler than trial and error.

TMT

[Too_Many_Tools]

On Nov 23, 9:35 am, dave <d...@dave.dave> wrote:
> Too_Many_Tools wrote:
> > On Nov 22, 8:04 am, dave<d...@dave.dave>  wrote:
> >> Too_Many_Tools wrote:

> >>> TheUnelcoModel 1914 Radio was a simple 60's-70's muliband radio that

> >>> used different coils to change bands.
>
> >>>http://images.craigslist.org/3k63o33l85O65Z65S3a87c9fd7652cece1adf.jpg
>
> >>>http://www.antiqueradios.com/forums/viewtopic.php?p=1057824&sid=6924e...
>
> >>> Does anyone know what the coil values were?
>
> >>> Thanks for any info.
>
> >> X sub L = X sub C at resonance.
>
> > Thanks for the formula but I want the ACTUAL values.
>
> > Anyone?
>

> You may have to wind your own coils.- Hide quoted text -
>
> - Show quoted text -

I expect to...I would be shocked to come across sets of coils for this
radio.

So again I need the values.

TMT

[RHF]

Are the Coils "Plug-in" Coils ?
http://www.valve-radio.co.uk/Radio_components/eddystonecoil.jpg

-or- Are the Coils "Solder-in" Coils ?
http://www.neidlinger.us/osc1small.jpg

Is there One Coil ?
-or- Two Coils to a Set ?

Do the Coils have 2-Pins ? -or- 4-Pins ?
http://www.io.com/~nielw/3tubrcvr/3tubcoil.jpg

Note - Some Coils have more 'Pins' 6-o/a-8
-but- Only use 2~4 Pins for the 1(2pin)~2(4pin) Coils.
http://www.nationalrf.com/images/plugin.jpg
.
.
Coil Shortwave Radio (Unelco - Model 1914)
http://www.iclassifieds.com/forsale/antiques/600287246/coil-shortwave-radio-unelco-model-1914.html

-image-
http://t1.gstatic.com/images?q=tbn:hIy5Ppzw-h9aXM:http://images.craigslist.org/3k63o33l85O65Z65S3a87c9fd7652cece1adf.jpg&t=1

-info-
Model 1914 made by Unelco Electronics Corp.
http://www.antiqueradios.com/forums/viewtopic.php?p=1057824&sid=6924e5d51977bd4f787b6bc0a6754a3f

-my-first-radio-
Unelco "OverSeas" radio (model 1914).
It was a solid state short wave radio sold at Sears.
There were plug-in coils to change bands.
http://www.tuberadioforum.com/the-clubhouse-f1/your-first-radio-t524.htm

. . . cause the more you know . . .
often brings about the realization
just how little you do know . . . ~ RHF
.
.

[dna...@gmail.com]

I actually opened a couple of the coils up. It was easy as the bottom simply unscrews. Inside is a coil, a few caps, and what looks to be a trimmer of some sort. I doesn't seem like a simple coil with its litz wire and ferrite core. I'll see if I can't post a photo here somehow.

[dave]

[kb4...@gmail.com]

Can you draw a diagram of each of the coils you have showing the connections to the tube pins?

Thanks, Al, KB4RA