On 13 Mar 2004 19:00:20 GMT, (Avery Fineman)
wrote:

[nostalgic history lesson snipped]
Quintuplers CAN be made, but, so far, Paul hasn't explained
enough specifics about his circuit, or how he is sensing any 5th
harmonic for any of us to get a good handle on a possible aid.

There's now the schematic of the relevant stages viewable on abse. If
there's anything else that's unclear, please feel free to ask for
clarification.

Note: Lacking any spectrum analyzer, a wide-range HF receiver
with an S meter can be an indicator...but such needs to be checked
against a calibrated signal generator for compensation of varying
S meter indication versus input levels. That's what I use for
checking HF levels (Icom R70) and it has been calibrated against
a reasonably-known-level RF source.

Len, you're a genius! I'd totally forgotten about that old dodge. Now
I have just the job in the attic: an aging Yaesu FT767GX that hasn't
been used for years, just lying around waiting to have its front end
blown up! :-)
Thanks!
--

The BBC: Licensed at public expense to spread lies.

On 13 Mar 2004 11:34:46 -0800, (Tom Bruhns) wrote:

In addition to what John L. posted about adding in 4th and 6th
harmonics and making it harder to filter, if you have a 40% or 60% (or
20% or 80%) duty cycle, there will be NO fifth harmonic. From what
you've posted, that likely is the crux of your problem.

Nope! You obviously haven't seen the scope traces I posted earlier
(given a clean bill of health by John Fields). Keep thinking!
--

The BBC: Licensed at public expense to spread lies.

On Sat, 13 Mar 2004 13:31:26 -0800, John Larkin
wrote:

I don't know of any really fast Schmitts. An HC14 followed by an AC04
should have fast edges. My favorite thing like this is an OnSemi
NL37WZ16 with all three sections in parallel. Powered from +6 or so,
it puts 5 volts into 50 ohms in something like 750 ps.

The old original RCA AC-series parts were sub-ns - crude and rude,
they were - but some ACs are now a little slower to reduce ground
bounce.

Most of the LVDS-to-TTL LVDS line receivers make damned fine
comparators with sub-ns output edges.

For screaming edges, there's always the step-recovery diode, or a
medium-power gaasfet like the CLY2.

Thanks, John.
I don't see the need for anything super-fast in this instance (I mean
- 3 to4 Mhz for God's sake) but was just curious as to what they use
in UHF and beyond...
2morrow I'm going to stick Reg's 17.2Mhz BPF in line and see if that
kills the 3rd enough to allow the 5th to thrive.
--

The BBC: Licensed at public expense to spread lies.

On Sat, 13 Mar 2004 13:31:26 -0800, John Larkin
wrote:

I don't know of any really fast Schmitts. An HC14 followed by an AC04
should have fast edges. My favorite thing like this is an OnSemi
NL37WZ16 with all three sections in parallel. Powered from +6 or so,
it puts 5 volts into 50 ohms in something like 750 ps.

The old original RCA AC-series parts were sub-ns - crude and rude,
they were - but some ACs are now a little slower to reduce ground
bounce.

Most of the LVDS-to-TTL LVDS line receivers make damned fine
comparators with sub-ns output edges.

For screaming edges, there's always the step-recovery diode, or a
medium-power gaasfet like the CLY2.

Thanks, John.
I don't see the need for anything super-fast in this instance (I mean
- 3 to4 Mhz for God's sake) but was just curious as to what they use
in UHF and beyond...
2morrow I'm going to stick Reg's 17.2Mhz BPF in line and see if that
kills the 3rd enough to allow the 5th to thrive.
--

The BBC: Licensed at public expense to spread lies.

On 13 Mar 2004 11:34:46 -0800, (Tom Bruhns) wrote:

In addition to what John L. posted about adding in 4th and 6th
harmonics and making it harder to filter, if you have a 40% or 60% (or
20% or 80%) duty cycle, there will be NO fifth harmonic. From what
you've posted, that likely is the crux of your problem.

Nope! You obviously haven't seen the scope traces I posted earlier
(given a clean bill of health by John Fields). Keep thinking!
--

The BBC: Licensed at public expense to spread lies.

On 13 Mar 2004 19:00:19 GMT, (Avery Fineman)
wrote:

In a way, it IS. Fifth harmonic of an infinitely sharp transition
rectangular waveform is still low in energy compared to the
fundamental. Chances are that a single stage using an active
device as a quintupler will NOT be successful, transistor or tube
(valve).

I find that surprising but bow to your superior knowledge...

Let's get to some specifics on this problem -

1. Let us know what you are using to determine whether or not
a 5th harmonic exists. The lack of indication may be due to
whatever it is (not a spectrum analyzer) being used.

As I said, since I've disposed of my SA I have no way of detecting the
presence of the 5th unless it's strong enough to be seen by 'scope or
read by my frequency counter. (Except for your brilliant idea of using
an HF rx, that is, which I intend to implement 2morrow).

2. Describe the multiplier stage in more detail and include an
approximate level and impedance/admittance of the RF
source. That would include supply rails and biasing.

There's a circuit diagram now viewable on abse under a similar thread
title. That should answer all your queries...

3. Describe whatever is being used to select the 5th harmonic
and inhibit the fundamental and other harmonics. There's
lots of energy at many different frequencies floating around
there and you only want one frequency.

Nothing more than what you can see in the schematic's two stages.

4. Review again with us the output drive level requirements so
we can get a handle on that.

It's got to eventually end up feeding another CMOS inverter for a
tripler stage.

5. If you are using an oscilloscope to measure the fundamental
waveform, estimate the actual risetime/falltime based on the
rise/fall times limits of the oscilloscope. That yields some
basic data that can be applied to a Fourier series to determine
the level of 5th harmonic energy you have to work with. [that
will also reveal the approximate frequency limits of the scope]

I prefer to go by the device's datasheet. In this case, the r/f times
are 7 to 8nS.

If there's anything I've missed out, lemme know...

--

The BBC: Licensed at public expense to spread lies.

On 13 Mar 2004 19:00:19 GMT, (Avery Fineman)
wrote:

In a way, it IS. Fifth harmonic of an infinitely sharp transition
rectangular waveform is still low in energy compared to the
fundamental. Chances are that a single stage using an active
device as a quintupler will NOT be successful, transistor or tube
(valve).

I find that surprising but bow to your superior knowledge...

Let's get to some specifics on this problem -

1. Let us know what you are using to determine whether or not
a 5th harmonic exists. The lack of indication may be due to
whatever it is (not a spectrum analyzer) being used.

As I said, since I've disposed of my SA I have no way of detecting the
presence of the 5th unless it's strong enough to be seen by 'scope or
read by my frequency counter. (Except for your brilliant idea of using
an HF rx, that is, which I intend to implement 2morrow).

2. Describe the multiplier stage in more detail and include an
approximate level and impedance/admittance of the RF
source. That would include supply rails and biasing.

There's a circuit diagram now viewable on abse under a similar thread
title. That should answer all your queries...

3. Describe whatever is being used to select the 5th harmonic
and inhibit the fundamental and other harmonics. There's
lots of energy at many different frequencies floating around
there and you only want one frequency.

Nothing more than what you can see in the schematic's two stages.

4. Review again with us the output drive level requirements so
we can get a handle on that.

It's got to eventually end up feeding another CMOS inverter for a
tripler stage.

5. If you are using an oscilloscope to measure the fundamental
waveform, estimate the actual risetime/falltime based on the
rise/fall times limits of the oscilloscope. That yields some
basic data that can be applied to a Fourier series to determine
the level of 5th harmonic energy you have to work with. [that
will also reveal the approximate frequency limits of the scope]

I prefer to go by the device's datasheet. In this case, the r/f times
are 7 to 8nS.

If there's anything I've missed out, lemme know...

--

The BBC: Licensed at public expense to spread lies.

On Sat, 13 Mar 2004 16:51:48 +0000, Paul Burridge wrote:

On 13 Mar 2004 07:33:15 -0800, (Tim Shoppa)
wrote:

Fifth harmonic frequency multipliers do exist, but it's usually much
easier to double and triple your way to the final frequency if possible.
(You just discovered this, I think!)

Yeah, but trying to get the 5th is hardly asking for the moon...

The lack of even harmonics is typical of push-pull stages ... if you
are messing around with CMOS gates, you might try using a TTL gate
(which pulls low much stronger than it pulls high) or an open collector
TTL gate, both with smmallish (100-200 ohm) pull-up resistors for
doubling.

I've a reasonably fast Schmitt I'm going to stick in there in place of
the 74HC04 before I resort to anything fancy (same pin-out).

Why not do a x3 followed by a x2 to get 17.2 MHz out of 2.866 MHz?

Because I don't have a rock lying about for that fundamental!

Hopefully some supreme being here will spot a problem with the traces
I've now posted...

Just a rough guess, since your calling on supreme beings...

That input cap... I take it the input source is a reasonable
estimate of your square wave... if the time constant of that input
RC net isn't right, it'll be a differentiator, and turn your square
wave into pulses coincident with the rising and falling edges. Your
scope trace suggested otherwise, but IIRC, at that tin=me you were
using the filter at the input to the mult., xo things have changed.

It doesn't look like you're biased in Class C. All the mults I've
seen are Class C biased with the tuned circuit on the collector. And
remember, when you're doing this later for some other purpose, in
Class C, the transistors Vceo - reverse breakdown - must be at least
twice the supply voltage.

--
Best Regards,
Mike

On Sat, 13 Mar 2004 16:51:48 +0000, Paul Burridge wrote:

On 13 Mar 2004 07:33:15 -0800, (Tim Shoppa)
wrote:

Fifth harmonic frequency multipliers do exist, but it's usually much
easier to double and triple your way to the final frequency if possible.
(You just discovered this, I think!)

Yeah, but trying to get the 5th is hardly asking for the moon...

The lack of even harmonics is typical of push-pull stages ... if you
are messing around with CMOS gates, you might try using a TTL gate
(which pulls low much stronger than it pulls high) or an open collector
TTL gate, both with smmallish (100-200 ohm) pull-up resistors for
doubling.

I've a reasonably fast Schmitt I'm going to stick in there in place of
the 74HC04 before I resort to anything fancy (same pin-out).

Why not do a x3 followed by a x2 to get 17.2 MHz out of 2.866 MHz?

Because I don't have a rock lying about for that fundamental!

Hopefully some supreme being here will spot a problem with the traces
I've now posted...

Just a rough guess, since your calling on supreme beings...

That input cap... I take it the input source is a reasonable
estimate of your square wave... if the time constant of that input
RC net isn't right, it'll be a differentiator, and turn your square
wave into pulses coincident with the rising and falling edges. Your
scope trace suggested otherwise, but IIRC, at that tin=me you were
using the filter at the input to the mult., xo things have changed.

It doesn't look like you're biased in Class C. All the mults I've
seen are Class C biased with the tuned circuit on the collector. And
remember, when you're doing this later for some other purpose, in
Class C, the transistors Vceo - reverse breakdown - must be at least
twice the supply voltage.

--
Best Regards,
Mike

On Sat, 13 Mar 2004 20:35:34 +0000, John Woodgate
wrote:

I read in sci.electronics.design that Reg Edwards
wrote (in
et.com) about 'Extracting the 5th Harmonic', on Sat, 13 Mar 2004:
Then along came Oliver Heaviside who turned the World upside down by
replacing jw with p.

I should probably change my name to Phon .oodgate in his honour. (;-)

It came out as Poodgate in my use of the transform ... ;-)