Please take a look at
alt.binaries.schematics.electronic

tnx


--

73
Hank WD5JFR

After checking out the patent no. 1626391, I misread the number previously.
It was patent in 1927 so I guess it was for TRF receivers, giving them a
wider tuning range and perhaps a neater dial cal. Does anyone recall who
might have used them?
tnx

--

73
Hank WD5JFR
"Henry Kolesnik" wrote in message
et...
Please take a look at
alt.binaries.schematics.electronic

tnx


--

73
Hank WD5JFR

There was an article in Antique Radio Classified some years ago that
made me aware of capacitors with tapered plates.

You can look up that patent online www.uspto.gov, click on search
under patents, click on patent number search, put in the number,
and when it tells you click on images. You have to have a tiff viewer
plugin in your web browser to read them. That particular patent seems
to apply to a capacitor with flat plates, so perhaps there was a pending
patent on the tapered plates.

A variable capacitor with semicircular plates and the axis of rotation
going through the middle and flat plates gives of course a linear
relationship between capacitance and angular rotation. By altering the
plate shape a bit and moving the axis of rotation off-center you can
get a capacitor that tunes straight-line wavelength. Wavelength is
proportional to the square root of capacitance. In the early days of
radio wavelength was often specified instead of frequency.

You can make a variable capacitor that is straight-line frequency, which
rotation has to be proportional to the reciprocal of the square root of
capacitance. With flat plates this requires a fairly radical plate
shape, with the axis of rotation very far off center. As a result there
has to be a lot of empty space for those long narrow plates to swing around.
I'll post a picture of one of these to that binaries group.

So a way to get around the odd plate shape and the space it occupies
is to use plates of tapered thickness. It would be nice if you got
straight-line something, but even if you don't you have something
where the stations are more spread out than they are with straight
line capacitance.

I have an old TRF receiver of the vintage of multiple knobs and 01A tubes
that uses capacitors like this.
--

jhhaynes at earthlink dot net

Jim
Who made your TRF with this cap and are the dials calibrated, if so f or
wavelength?
tnx

--

73
Hank WD5JFR
"Jim Haynes" wrote in message
k.net...
There was an article in Antique Radio Classified some years ago that
made me aware of capacitors with tapered plates.

You can look up that patent online www.uspto.gov, click on search
under patents, click on patent number search, put in the number,
and when it tells you click on images. You have to have a tiff viewer
plugin in your web browser to read them. That particular patent seems
to apply to a capacitor with flat plates, so perhaps there was a pending
patent on the tapered plates.

A variable capacitor with semicircular plates and the axis of rotation
going through the middle and flat plates gives of course a linear
relationship between capacitance and angular rotation. By altering the
plate shape a bit and moving the axis of rotation off-center you can
get a capacitor that tunes straight-line wavelength. Wavelength is
proportional to the square root of capacitance. In the early days of
radio wavelength was often specified instead of frequency.

You can make a variable capacitor that is straight-line frequency, which
rotation has to be proportional to the reciprocal of the square root of
capacitance. With flat plates this requires a fairly radical plate
shape, with the axis of rotation very far off center. As a result there
has to be a lot of empty space for those long narrow plates to swing
around.
I'll post a picture of one of these to that binaries group.

So a way to get around the odd plate shape and the space it occupies
is to use plates of tapered thickness. It would be nice if you got
straight-line something, but even if you don't you have something
where the stations are more spread out than they are with straight
line capacitance.

I have an old TRF receiver of the vintage of multiple knobs and 01A tubes
that uses capacitors like this.
--

jhhaynes at earthlink dot net

Hallicrafter, Telefunken, Nordmende, etc all used similar caps in their TRF
recievers, as did ARC5,ARC 7, and quite a few of the communication
transcievers used in the late 30's early 40's. I had operational ARC 5 and
ARC 7 with the external Antenna Tuning box in the late 50's. Made nice QRP
devices excepting the QRM generated.
73 AJ (Retired QRP Pain!!)
"Henry Kolesnik" wrote in message
m...
Jim
Who made your TRF with this cap and are the dials calibrated, if so f or
wavelength?
tnx

--

73
Hank WD5JFR
"Jim Haynes" wrote in message
k.net...
There was an article in Antique Radio Classified some years ago that
made me aware of capacitors with tapered plates.

You can look up that patent online www.uspto.gov, click on search
under patents, click on patent number search, put in the number,
and when it tells you click on images. You have to have a tiff viewer
plugin in your web browser to read them. That particular patent seems
to apply to a capacitor with flat plates, so perhaps there was a pending
patent on the tapered plates.

A variable capacitor with semicircular plates and the axis of rotation
going through the middle and flat plates gives of course a linear
relationship between capacitance and angular rotation. By altering the
plate shape a bit and moving the axis of rotation off-center you can
get a capacitor that tunes straight-line wavelength. Wavelength is
proportional to the square root of capacitance. In the early days of
radio wavelength was often specified instead of frequency.

You can make a variable capacitor that is straight-line frequency, which
rotation has to be proportional to the reciprocal of the square root of
capacitance. With flat plates this requires a fairly radical plate
shape, with the axis of rotation very far off center. As a result there
has to be a lot of empty space for those long narrow plates to swing
around.
I'll post a picture of one of these to that binaries group.

So a way to get around the odd plate shape and the space it occupies
is to use plates of tapered thickness. It would be nice if you got
straight-line something, but even if you don't you have something
where the stations are more spread out than they are with straight
line capacitance.

I have an old TRF receiver of the vintage of multiple knobs and 01A tubes
that uses capacitors like this.
--

jhhaynes at earthlink dot net

In article ,
Henry Kolesnik wrote:

Jim
Who made your TRF with this cap and are the dials calibrated, if so f or
wavelength?
tnx

Well, it's a mystery. There is no manufacturer's name on it anywhere. And
all the parts are from various well-known parts vendors (except no labels
on the coils). There are several theories:
Might be a home-built set - if so, it's incredibly well done, including
an engraved front panel
Might be built from a kit - but then you'd think the kit manufacturer
would have put a name on it somewhere.
Might be a factory-built set for some department-store chain that was
to attach their own brand label, tho there is no evidence that one
ever was attached.
Might be a factory-built set and the maker is deliberately non-identified
to avoid paying royalties on the Neutrodyne patents. Which could also
apply to a kit. I read some early superhets were sold as kits to get
around paying patent royalties.
Someone suggested a fly-by-night manufacturer, who would come into a
village with a wagon load of receivers, and secretly bring another
wagon with a transmitter. The transmitter would assure they had a
good signal while they were selling the receivers; and once they were
all sold they could move on. However this receiver is certainly not
shoddily constructed.

Any other theories?
--

jhhaynes at earthlink dot net

In article ,
Henry Kolesnik wrote:
Jim
Who made your TRF with this cap and are the dials calibrated, if so f or
wavelength?
tnx
The dials are not calibrated in frequency or wavelength. They look like
National vernier dials, calibrated 0-100.
--

jhhaynes at earthlink dot net

I never heard of the transmitter scam before and I would think that people
would have wanted to hear their favorite 2 or 3 stations. I wonder how they
did the scam?
Hank
"Jim Haynes" wrote in message
ink.net...
In article ,
Henry Kolesnik wrote:

Jim
Who made your TRF with this cap and are the dials calibrated, if so f or
wavelength?
tnx

Well, it's a mystery. There is no manufacturer's name on it anywhere.
And
all the parts are from various well-known parts vendors (except no labels
on the coils). There are several theories:
Might be a home-built set - if so, it's incredibly well done, including
an engraved front panel
Might be built from a kit - but then you'd think the kit manufacturer
would have put a name on it somewhere.
Might be a factory-built set for some department-store chain that was
to attach their own brand label, tho there is no evidence that one
ever was attached.
Might be a factory-built set and the maker is deliberately
non-identified
to avoid paying royalties on the Neutrodyne patents. Which could
also
apply to a kit. I read some early superhets were sold as kits to get
around paying patent royalties.
Someone suggested a fly-by-night manufacturer, who would come into a
village with a wagon load of receivers, and secretly bring another
wagon with a transmitter. The transmitter would assure they had a
good signal while they were selling the receivers; and once they were
all sold they could move on. However this receiver is certainly not
shoddily constructed.

Any other theories?
--

jhhaynes at earthlink dot net

I have an Allen-Cardwell cap with a plate set that looks sort of like a
French curve. It appears irridited (gold-looking color?) and came from
a test set of some sort, but its been too long ago to remember...hi!

On Fri, 11 Nov 2005 12:44:51 +0000, Henry Kolesnik wrote:

I never heard of the transmitter scam before and I would think that people
would have wanted to hear their favorite 2 or 3 stations. I wonder how they
did the scam?
Hank
"Jim Haynes" wrote in message
ink.net...
In article ,
Henry Kolesnik wrote:

How could they have 2 or 3 favorite stations if they didn't have a radio?

--
Jim Mueller

To get my real email address, replace wrongname with eportiz.
Then replace nospam with sacbeemail.