In article , Paul Burridge
writes:

What's the maximum multiplication factor it's practical and sensible
to attempt to achieve in one single stage of multiplication? (Say from
a 7Mhz square wave source with 5nS rise/fall times.)

Paul, past state of the hardware art (past 60 years) indicates that
triplers are the practical maximum. Quintuplers have been done
but those are rare in described applications.

In 1955 I had hands-on experience with a septupler (7 x multiplier)
using a 2C39 and a cavity-tuned plate circuit at 1.8 GHz. That was
in a General Electric microwave radio relay terminal designed about
1950. Of nine terminals, two had to "QSY" to new crystal-controlled
microwave center frequencies for second-level contingency operation.
Difficult and fussy to do but was do-able...the crystal was also 7th
overtone in a vacuum tube oscillator but was followed by a buffer
stage feeding a tripler, another buffer, then the septupler which fed
another 2C39 as the pulse-modulated final for 12 W peak output at
1.8 GHz. [from memory and 35mm slides...big GE manual went to
recycle a long time ago] That's the only septupler application that
I am aware of...no doubt there are others, somewhere.

General Electric must have had some division/work-group with lots
of work in old frequency control methods. A local NTSC color sub-
carrier generator-regenerator made by GE had extensive use of
"locked oscillators" for frequency multiplication and division, but
mostly at frequencies lower than 7 MHz. Haven't come across any
practical hardware on locked oscillators except for two mentions in
older journals, trade papers. One of those used transistors as
active devices.

Doublers and quadruplers have been made using both diodes and
tube-or-transistor active devices. That's relatively easy with non-
square waveforms (distorted sinewaves); square waves have high
odd harmonic energy, low even harmonic energy.

Making practical, reproducible active multipliers in the home shop
is, practically, a trial-and-error process involving playing with cut-
off bias of the active device input, energy and harmonic content of
the source, and Q of the multiplier's output stage. In the past I've
made tripling-in-the-plate pentode crystal oscillators using
fundamental frequency quartz but those were highly dependent on
getting the highest impedance tuned plate circuit and needed
scope viewing to check output waveforms. Not very reproducible.
There's no "easy" way to do it that will "work every time" despite
the claims of many. :-)

Digital division IS straightforward up to about 1 GHz based on
such technology over the last 3 decades. That's why PLLs came
to prominence in frequency control techniques up to UHF.

Len Anderson
retired (from regular hours) electronic engineer person

On Mon, 16 Feb 2004 19:40:00 GMT, "W3JDR" wrote:

" Starting with a perfect square wave at f1, bang the hell out of a diode
with it, and then bandpass it and the 3rd harmonic (f2) separately, then
mix them to get f1, f2, f1+f2, and f1-f2. Using a doubly balanced mixer
will get rid of f1 and f2, then notching out f1+f2 will leave f1-f2,
which will be 2f1, that non-existent second harmonic."

Oh yuchh...that sounds painful!

---
Just making a point for Mr. T. :-)

Why not just distort the symmetry of the square digitally (like drive it into an exclusive-or with a small delay on one input) to make a short impulse, then bandpass filter the output? Or staying in the purely digital domain, use same said exclusive-or and delay one of the two inputs by t/4 (t=period of input sq wave) and get a 2*F square wave out.

---
Sure, why not?

--
John Fields

On Mon, 16 Feb 2004 19:40:00 GMT, "W3JDR" wrote:

" Starting with a perfect square wave at f1, bang the hell out of a diode
with it, and then bandpass it and the 3rd harmonic (f2) separately, then
mix them to get f1, f2, f1+f2, and f1-f2. Using a doubly balanced mixer
will get rid of f1 and f2, then notching out f1+f2 will leave f1-f2,
which will be 2f1, that non-existent second harmonic."

Oh yuchh...that sounds painful!

---
Just making a point for Mr. T. :-)

Why not just distort the symmetry of the square digitally (like drive it into an exclusive-or with a small delay on one input) to make a short impulse, then bandpass filter the output? Or staying in the purely digital domain, use same said exclusive-or and delay one of the two inputs by t/4 (t=period of input sq wave) and get a 2*F square wave out.

---
Sure, why not?

--
John Fields

In article , "W3JDR"
writes:

This is a multi-part message in MIME format.

------=_NextPart_000_00CD_01C3F49A.C1DF8CA0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

" Starting with a perfect square wave at f1, bang the hell out of a =
diode
with it, and then bandpass it and the 3rd harmonic (f2) separately, =
then
mix them to get f1, f2, f1+f2, and f1-f2. Using a doubly balanced =
mixer
will get rid of f1 and f2, then notching out f1+f2 will leave f1-f2,
which will be 2f1, that non-existent second harmonic."
=20
Oh yuchh...that sounds painful!=20
Why not just distort the symmetry of the square digitally (like drive it =
into an exclusive-or with a small delay on one input) to make a short =
impulse, then bandpass filter the output? Or staying in the purely =
digital domain, use same said exclusive-or and delay one of the two =
inputs by t/4 (t=3Dperiod of input sq wave) and get a 2*F square wave =
out.

...or just use a small toroid transformer, a pair of diodes arranged
like a full-wave rectifier for wideband frequency doubling? :-)

While using digitial techniques sounds cool at first, the above
technique can generate all kinds of PM that isn't noticed on time-
domain viewing with a scope. There are many ways to cure that PM
or incidental FM but all involve lots more circuitry than the simple
diode doubler which can be inherently broadband over half an octave.

Depends on the application of the multiplier and the overall specs
on purity of the multiplied RF.

Len Anderson
retired (from regular hours) electronic engineer person

In article , "W3JDR"
writes:

This is a multi-part message in MIME format.

------=_NextPart_000_00CD_01C3F49A.C1DF8CA0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

" Starting with a perfect square wave at f1, bang the hell out of a =
diode
with it, and then bandpass it and the 3rd harmonic (f2) separately, =
then
mix them to get f1, f2, f1+f2, and f1-f2. Using a doubly balanced =
mixer
will get rid of f1 and f2, then notching out f1+f2 will leave f1-f2,
which will be 2f1, that non-existent second harmonic."
=20
Oh yuchh...that sounds painful!=20
Why not just distort the symmetry of the square digitally (like drive it =
into an exclusive-or with a small delay on one input) to make a short =
impulse, then bandpass filter the output? Or staying in the purely =
digital domain, use same said exclusive-or and delay one of the two =
inputs by t/4 (t=3Dperiod of input sq wave) and get a 2*F square wave =
out.

...or just use a small toroid transformer, a pair of diodes arranged
like a full-wave rectifier for wideband frequency doubling? :-)

While using digitial techniques sounds cool at first, the above
technique can generate all kinds of PM that isn't noticed on time-
domain viewing with a scope. There are many ways to cure that PM
or incidental FM but all involve lots more circuitry than the simple
diode doubler which can be inherently broadband over half an octave.

Depends on the application of the multiplier and the overall specs
on purity of the multiplied RF.

Len Anderson
retired (from regular hours) electronic engineer person

On Mon, 16 Feb 2004 13:03:46 -0600, John Fields
posted this:


Starting with a perfect square wave at f1, bang the hell out of a diode
with it, and then bandpass it and the 3rd harmonic (f2) separately, then
mix them to get f1, f2, f1+f2, and f1-f2. Using a doubly balanced mixer
will get rid of f1 and f2, then notching out f1+f2 will leave f1-f2,
which will be 2f1, that non-existent second harmonic.

What purpose does the diode serve? You're already starting with a
"perfect" square wave.

OTOH, if you have had some bad experiences with diodes in the past, I
can easily understand your tendency to abuse them as often as you can.

Jim

On Mon, 16 Feb 2004 13:03:46 -0600, John Fields
posted this:


Starting with a perfect square wave at f1, bang the hell out of a diode
with it, and then bandpass it and the 3rd harmonic (f2) separately, then
mix them to get f1, f2, f1+f2, and f1-f2. Using a doubly balanced mixer
will get rid of f1 and f2, then notching out f1+f2 will leave f1-f2,
which will be 2f1, that non-existent second harmonic.

What purpose does the diode serve? You're already starting with a
"perfect" square wave.

OTOH, if you have had some bad experiences with diodes in the past, I
can easily understand your tendency to abuse them as often as you can.

Jim

I read in sci.electronics.design that John Fields jfields@austininstrum
ents.com wrote (in ) about
'Frequency multiplication', on Mon, 16 Feb 2004:

Starting with a perfect square wave at f1, bang the hell out of a diode
with it, and then bandpass it and the 3rd harmonic (f2) separately, then
mix them to get f1, f2, f1+f2, and f1-f2. Using a doubly balanced mixer
will get rid of f1 and f2, then notching out f1+f2 will leave f1-f2,
which will be 2f1, that non-existent second harmonic.

No need to abuse any diodes. The third harmonic is already there, just
10 dB down. You only need a bit of gain after the peaky filter.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

I read in sci.electronics.design that John Fields jfields@austininstrum
ents.com wrote (in ) about
'Frequency multiplication', on Mon, 16 Feb 2004:

Starting with a perfect square wave at f1, bang the hell out of a diode
with it, and then bandpass it and the 3rd harmonic (f2) separately, then
mix them to get f1, f2, f1+f2, and f1-f2. Using a doubly balanced mixer
will get rid of f1 and f2, then notching out f1+f2 will leave f1-f2,
which will be 2f1, that non-existent second harmonic.

No need to abuse any diodes. The third harmonic is already there, just
10 dB down. You only need a bit of gain after the peaky filter.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

On Mon, 16 Feb 2004 21:02:02 GMT, James Meyer
wrote:

On Mon, 16 Feb 2004 13:03:46 -0600, John Fields
posted this:


Starting with a perfect square wave at f1, bang the hell out of a diode
with it, and then bandpass it and the 3rd harmonic (f2) separately, then
mix them to get f1, f2, f1+f2, and f1-f2. Using a doubly balanced mixer
will get rid of f1 and f2, then notching out f1+f2 will leave f1-f2,
which will be 2f1, that non-existent second harmonic.

What purpose does the diode serve? You're already starting with a
"perfect" square wave.

---
Duhhh.... None, of course.

Thanks.
--
John Fields