The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular unit has
got a problem.

What is your experience on function generators frequency stability?

Thanks & 73

Tony
Rome, Italy

"Antonio I0JX" wrote in
:

The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular
unit has got a problem.

What is your experience on function generators frequency stability?

Thanks & 73

Tony
Rome, Italy



it depends on the clock source;
some generators use better,ovenized crystal timebases.
The HP synthesizers had an option for high stability timebases,ISTR.
or you can feed in an external timebase.
At TEK,I used to feed a HP3336 with the output from my WWVB receiver.

--
Jim Yanik
jyanik
at
localnet
dot com

"Jim Yanik" ha scritto nel messaggio
4...

"Antonio I0JX" wrote in
:

The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular
unit has got a problem.

What is your experience on function generators frequency stability?

Thanks & 73

Tony
Rome, Italy



it depends on the clock source;
some generators use better,ovenized crystal timebases.
The HP synthesizers had an option for high stability timebases,ISTR.
or you can feed in an external timebase.
At TEK,I used to feed a HP3336 with the output from my WWVB receiver.

--
Jim Yanik
jyanik
at
localnet
dot com

Thanks Jim.

the oscillator of my HP function generator utilizes a circuit whereby a
capacitor is charged at constant current, and frequency is adjusted by a
front-panel potentiometer. One may not expect much from that, but frequency
stability is really bad. I should find someone having a generator working on
the same principle, if not just the same HP model.

Regards.

Tony

"Antonio I0JX" wrote in
:



"Jim Yanik" ha scritto nel messaggio
4...

"Antonio I0JX" wrote in
:

The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular
unit has got a problem.

What is your experience on function generators frequency stability?

Thanks & 73

Tony
Rome, Italy



it depends on the clock source;
some generators use better,ovenized crystal timebases.
The HP synthesizers had an option for high stability timebases,ISTR.
or you can feed in an external timebase.
At TEK,I used to feed a HP3336 with the output from my WWVB receiver.


Thanks Jim.

the oscillator of my HP function generator utilizes a circuit whereby a
capacitor is charged at constant current, and frequency is adjusted by a
front-panel potentiometer. One may not expect much from that, but frequency
stability is really bad. I should find someone having a generator working
on
the same principle, if not just the same HP model.

Regards.

Tony


my apologies,I had thought that the HP33xx series were all digital
synthesizers.
you're not going to get "good" freq stability from an analog generator.

does the freq. stability meet the specs?
if so,are the specs good enough for what you want?

maybe your potentiometer is dirty or noisy,or some capacitor in the current
source has gone bad.



maybe I'll go look at the schematics and specs,if I can find the manual and
it's not a huge file.

--
Jim Yanik
jyanik
at
localnet
dot com

does the freq. stability meet the specs?

The HP manual does not tell anything on frequency stability. No useful info
found on the web either.

if so,are the specs good enough for what you want?

Not at all. The instrument is nearly unusable for my purposes.

Frequency measurement results:

- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz
- 30 minutes after. Delta F = - 116 kHz
- 45 minutes after. Delta F = -132 kHz
- 60 minutes after. Delta F = -141 kHz
- 75 minutes after. Delta F = -147 kHz

maybe your potentiometer is dirty or noisy,or some capacitor in the current
source has gone bad.

I lubricated switches and potentiometers. A capacitor may well be, but it is
difficult to locate components on the board.

maybe I'll go look at the schematics and specs,if I can find the manual and
it's not a huge file.

Thanks. Anyway again my question is: is my generator faulty or all
instruments based on the same (analog) frequency generation principle
(charging a capacitor at constant current) behave more or less the same?
-

On 03/19/2012 05:17 PM, Antonio I0JX wrote:

does the freq. stability meet the specs?

The HP manual does not tell anything on frequency stability. No useful
info found on the web either.

if so,are the specs good enough for what you want?

Not at all. The instrument is nearly unusable for my purposes.

Frequency measurement results:

- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz
- 30 minutes after. Delta F = - 116 kHz
- 45 minutes after. Delta F = -132 kHz
- 60 minutes after. Delta F = -141 kHz
- 75 minutes after. Delta F = -147 kHz

maybe your potentiometer is dirty or noisy,or some capacitor in the current
source has gone bad.

I lubricated switches and potentiometers. A capacitor may well be, but
it is difficult to locate components on the board.

maybe I'll go look at the schematics and specs,if I can find the manual and
it's not a huge file.

Thanks. Anyway again my question is: is my generator faulty or all
instruments based on the same (analog) frequency generation principle
(charging a capacitor at constant current) behave more or less the same?
-

3% drift is pretty horrible, even for Wun Hung Lo. Something's busted.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

On 3/18/2012 4:32 PM, Antonio I0JX wrote:


"Jim Yanik" ha scritto nel messaggio
4...

"Antonio I0JX" wrote in
:

The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular
unit has got a problem.

What is your experience on function generators frequency stability?

Thanks & 73

Tony
Rome, Italy



it depends on the clock source;
some generators use better,ovenized crystal timebases.
The HP synthesizers had an option for high stability timebases,ISTR.
or you can feed in an external timebase.
At TEK,I used to feed a HP3336 with the output from my WWVB receiver.


Statements like "frequency stability is bad or poor will get you nowhere.
What are your requirements for stability?
Under what conditions? Temperature variability, time variability,
noise??? At what frequency?
What is the stability you are MEASURING?
What is the stability spec of the generator?
Stability is a NUMBER, not a vague statement of dissatisfaction.

HP equipment of that vintage was typically near the better end of
performance for equipment of that vintage. But even HP equipment breaks.
Performance is usually better near the top end of the dial.
Just 'cause you can get 1000:1 range on the knob doesn't mean
you should.

OK, I looked up the spec. I can't find any reference in the spec
to frequency stability, other than it takes an hour for the frequency
to get within 5% of the dial setting.
That oughta tell you something.

In general, if your requirements contain the word "stability",
a function generator is a poor choice.

Statements like "frequency stability is bad or poor will get you nowhere.
What are your requirements for stability?
Under what conditions? Temperature variability, time variability,
noise??? At what frequency?

My requirements are fairly modest. Just to tune HF receivers and their IF
chains. Say from 200 kHz to 10 MHz. Noise and temperature is not an issue
for my case.

What is the stability you are MEASURING?

Frequency measurement results:

- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz (drift = 6.5 kHz per minute)
- 30 minutes after. Delta F = - 116 kHz (drift = 3.7 kHz per minute)
- 45 minutes after. Delta F = -132 kHz (drift = 2.9 kHz per minute)
- 60 minutes after. Delta F = -141 kHz (drift = 2.3 kHz per minute)
- 75 minutes after. Delta F = -147 kHz (drift = 2.0 kHz per minute)

Drift is too high for any practical use.

What is the stability spec of the generator?
Stability is a NUMBER, not a vague statement of dissatisfaction.

Tell HP. They do not mention frequency stability in the manual and no useful
information can be found on the web.

HP equipment of that vintage was typically near the better end of
performance for equipment of that vintage. But even HP equipment breaks.
Performance is usually better near the top end of the dial.
Just 'cause you can get 1000:1 range on the knob doesn't mean
you should.

This is just I what I would to like to know: which is people experience with
non-HP generators using an analog frequency-generation circuit.

OK, I looked up the spec. I can't find any reference in the spec
to frequency stability, other than it takes an hour for the frequency
to get within 5% of the dial setting.
That oughta tell you something.

Well, that figure is also related to dial accuracy, but can serve to broadly
figure out frequency stability.

In general, if your requirements contain the word "stability",
a function generator is a poor choice.

I know, but if they produce them, they evidently serve to do something. In
my case there is nothing I can do with such a poor generator. And that is
HP! Again my question is: is my generator faulty or all
instruments based on the same (analog) frequency generation principle
(charging a capacitor at constant current) behave more or less the same?

Regards.

Tony

On 3/19/2012 2:33 PM, Antonio I0JX wrote:
Statements like "frequency stability is bad or poor will get you nowhere.
What are your requirements for stability?
Under what conditions? Temperature variability, time variability,
noise??? At what frequency?

My requirements are fairly modest. Just to tune HF receivers and their
IF chains. Say from 200 kHz to 10 MHz. Noise and temperature is not an
issue for my case.

Your requirements are not modest. You are asking the device to perform
a function it was never intended to do.

If you expect to tune receiver IF chains with a function generator,
you need to be willing to wait for everything to warm up, use a secondary
frequency measurement device and do the job quickly.
It does sweep, so you could sweep the IF and use a marker.

What is the stability you are MEASURING?

Frequency measurement results:

- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz (drift = 6.5 kHz per minute)
- 30 minutes after. Delta F = - 116 kHz (drift = 3.7 kHz per minute)
- 45 minutes after. Delta F = -132 kHz (drift = 2.9 kHz per minute)
- 60 minutes after. Delta F = -141 kHz (drift = 2.3 kHz per minute)
- 75 minutes after. Delta F = -147 kHz (drift = 2.0 kHz per minute)

I don't understand your numbers at all.
I see 6 kHz in 15 minutes. By my math, that's ~400 Hz. / minute

Drift is too high for any practical use.

Drift is just fine for the INTENDED uses.

TEK CFG280 11MHz sweep function generator.
Started at 5MHz.
Drifted up to 5.077 in 3 minutes, then started down.
After 52minutes it was back down to 5.022 and drifting
down at about 300Hz/minute.
Pretty similar to yours after initial warmup.
I made no attempt to factor out the startup drift of the
internal frequency counter.

What is the stability spec of the generator?
Stability is a NUMBER, not a vague statement of dissatisfaction.

Tell HP. They do not mention frequency stability in the manual and no
useful information can be found on the web.

HP equipment of that vintage was typically near the better end of
performance for equipment of that vintage. But even HP equipment breaks.
Performance is usually better near the top end of the dial.
Just 'cause you can get 1000:1 range on the knob doesn't mean
you should.

This is just I what I would to like to know: which is people experience
with non-HP generators using an analog frequency-generation circuit.

OK, I looked up the spec. I can't find any reference in the spec
to frequency stability, other than it takes an hour for the frequency
to get within 5% of the dial setting.
That oughta tell you something.

Well, that figure is also related to dial accuracy, but can serve to
broadly figure out frequency stability.
Remember, that's 5% of full scale.
So with a 1000:1 frequency range, that can be up to 5000% off.

In general, if your requirements contain the word "stability",
a function generator is a poor choice.

I know, but if they produce them, they evidently serve to do something.

A function generator is a very nice general purpose instrument.
You're using it for the wrong purpose.

Back in the day, I managed a function generator design group.
I don't remember a single discussion about frequency stability.
It was all about triangle linearity, square-wave transient response,
sine-wave distortion and amplitude flatness with frequency.

In my case there is nothing I can do with such a poor generator. And
that is HP! Again my question is: is my generator faulty or all
instruments based on the same (analog) frequency generation principle
(charging a capacitor at constant current) behave more or less the same?

There's nothing inherently unstable about the topology. But the devil
is in the details. A crystal is stable because you can't change the
frequency.
A function generator is designed for a 1000:1 frequency range.
That makes it exceedingly sensitive to parameter variations.


The HP is more vulnerable because it does include sweep functions
designed to change the frequency.
I'm stating the obvious here, but make sure the modulation functions are
set to
something other than FM.
And the inputs are grounded, including the VCO input on the back.

I'm too lazy to study the schematic, but anything connected to the
frequency path can inject drift. You might be able to cut loose some
of the sweep functions.

Power supply voltage is critical. Direct measurements are difficult because
of the small variations involved. Load the output with 50 ohms and vary
the amplitude from 0 to max. If the frequency changes, you might
want to check out the power supply. The reverse is not true.
If the frequency does not change, that doesn't rule out temperature
variations in the power supply voltages.

You can poke around inside with a tiny heat source. I use a catalytic
butane hot-air gun from Portasol. Freeze mist works too if you can still
find it. But, since there's a lot of temperature compensation going
on in the loop, heating one component in the loop may lead you astray.


Bottom line, I think your generator is working fine. You're using it
for an unintended purpose outside it's performance ability.

Regards.

Tony

"Jim Yanik"


it depends on the clock source;


** It's an analogue function generator.

Stability depends on the tempcos of Rs, Cs and pots.



..... Phil

"Antonio I0JX"

The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular unit
has got a problem.

What is your experience on function generators frequency stability?


** Normally, frequency stability relates to the internal temperature of a
generator - so frequency stability = temperature stability. If the
frequency varies independently of temperature, then there is something wrong
like a faulty frequency control pot.

In any case, the tempco of a carbon track pot ( as used in the 3312a) is way
higher than metal film resistors and film capacitors.

How bad is your unit's stability ?

If ( after a 1 hour warm up ) you set the gene at 10kHz and waited 30
minutes - what would the new frequency be?



..... Phil

** Normally, frequency stability relates to the internal temperature of a
generator - so frequency stability = temperature stability. If the
frequency varies independently of temperature, then there is something wrong
like a faulty frequency control pot.

In any case, the tempco of a carbon track pot ( as used in the 3312a) is way
higher than metal film resistors and film capacitors.

How bad is your unit's stability ?

If ( after a 1 hour warm up ) you set the gene at 10kHz and waited 30
minutes - what would the new frequency be?




Frequency measurement results:

- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz (drift = 6.5 kHz per minute)
- 30 minutes after. Delta F = - 116 kHz (drift = 3.7 kHz per minute)
- 45 minutes after. Delta F = -132 kHz (drift = 2.9 kHz per minute)
- 60 minutes after. Delta F = -141 kHz (drift = 2.3 kHz per minute)
- 75 minutes after. Delta F = -147 kHz (drift = 2.0 kHz per minute)

Drift is too high for any practical use.

Tried to lubricate potentiometers and switches with no success.

Again my question is: is my generator faulty or all instruments based on the
same (analog) frequency generation principle (charging a capacitor at
constant current) behave more or less the same?

Regards.

Tony

"Antonio I0JX"


Frequency measurement results:

- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz (drift = 6.5 kHz per minute)
- 30 minutes after. Delta F = - 116 kHz (drift = 3.7 kHz per minute)
- 45 minutes after. Delta F = -132 kHz (drift = 2.9 kHz per minute)
- 60 minutes after. Delta F = -141 kHz (drift = 2.3 kHz per minute)
- 75 minutes after. Delta F = -147 kHz (drift = 2.0 kHz per minute)

Drift is too high for any practical use.


** A function generator is ** NOT ** an RF generator !!!

The drift you are seeing is completely normal - for a function generator.

Bloody stupid radio ham.



..... Phil

On Sun, 18 Mar 2012 22:15:43 +0100, "Antonio I0JX"
wrote:

The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular unit has
got a problem.

What is your experience on function generators frequency stability?

How good stability were you expecting?
Are you asking about temperature stability, or just drift?

The HP3312A was not intended to be the ultimate stable frequency
standard. Just because it goes up to RF frequencies doesn't mean it
can substitute for a proper RF generator. If you look at the
specifications:
http://www.testbuyer.com/pdf/specs.cfm?pdf_id=55055909FB
you'll see that the frequency stability is not specified. That should
be a clue. Dial accuracy is only 5%, whatever that means.

If you want accuracy and stability, I suggest a synthesized function
generator.

If you want to do it yourself with a PLL, build an external phase
comparitor, with the output going to the FM sweep input, and the
inputs from the sync output, and a suitable frequency reference. A
1KHz reference frequency, will give a frequency output locked at 1KHz
intervals.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:

On Sun, 18 Mar 2012 22:15:43 +0100, "Antonio I0JX"
wrote:


The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular unit has
got a problem.

What is your experience on function generators frequency stability?


How good stability were you expecting?
Are you asking about temperature stability, or just drift?

The HP3312A was not intended to be the ultimate stable frequency
standard. Just because it goes up to RF frequencies doesn't mean it
can substitute for a proper RF generator. If you look at the
specifications:
http://www.testbuyer.com/pdf/specs.cfm?pdf_id=55055909FB
you'll see that the frequency stability is not specified. That should
be a clue. Dial accuracy is only 5%, whatever that means.

If you want accuracy and stability, I suggest a synthesized function
generator.

If you want to do it yourself with a PLL, build an external phase
comparitor, with the output going to the FM sweep input, and the
inputs from the sync output, and a suitable frequency reference. A
1KHz reference frequency, will give a frequency output locked at 1KHz
intervals.


or. get one of those DDS AF from Rigol like I did.

http://www.tequipment.net/RigolDG1022.html

Now there's a thing of beauty for the price. I got it when it was on
sale and paid less.

Jamie

The frequency stability of my HP3312A function generator is poor, very
annoying for any practical use. I am trying to determine whether that
behavior is fairly normal for function generators, or my particular unit
has
got a problem.

What is your experience on function generators frequency stability?

How good stability were you expecting?
Are you asking about temperature stability, or just drift?

The HP3312A was not intended to be the ultimate stable frequency
standard. Just because it goes up to RF frequencies doesn't mean it
can substitute for a proper RF generator. If you look at the
specifications:
http://www.testbuyer.com/pdf/specs.cfm?pdf_id=55055909FB
you'll see that the frequency stability is not specified. That should
be a clue. Dial accuracy is only 5%, whatever that means.

If you want accuracy and stability, I suggest a synthesized function
generator.

If you want to do it yourself with a PLL, build an external phase
comparitor, with the output going to the FM sweep input, and the
inputs from the sync output, and a suitable frequency reference. A
1KHz reference frequency, will give a frequency output locked at 1KHz
intervals.

Hi Jeff

Frequency measurement results a

- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz (drift = 6.5 kHz per minute)
- 30 minutes after. Delta F = - 116 kHz (drift = 3.7 kHz per minute)
- 45 minutes after. Delta F = -132 kHz (drift = 2.9 kHz per minute)
- 60 minutes after. Delta F = -141 kHz (drift = 2.3 kHz per minute)
- 75 minutes after. Delta F = -147 kHz (drift = 2.0 kHz per minute)

Drift is too high for any practical use.

But before throwing it in the waste basket (as I'll probably do in the end),
I would be curious to know the experience of other people having that
generator or a similar one using the same (analog) frequency generation
principle (charging a capacitor at constant current). Do all of them behave
more or less the same? Is my unit faulty?

Regards.

Tony

On Mon, 19 Mar 2012 22:42:47 +0100, "Antonio I0JX"
wrote:

Frequency measurement results a
- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz (drift = 6.5 kHz per minute)
- 30 minutes after. Delta F = - 116 kHz (drift = 3.7 kHz per minute)
- 45 minutes after. Delta F = -132 kHz (drift = 2.9 kHz per minute)
- 60 minutes after. Delta F = -141 kHz (drift = 2.3 kHz per minute)
- 75 minutes after. Delta F = -147 kHz (drift = 2.0 kHz per minute)

150KHz of 5000KHz is 3% drift. That's within the specified 5%.

Drift is too high for any practical use.

Really? I used a 3312A in the 1970's to do type certification on
various radios. It was perfectly suited for running as an audio sweep
generator, or for making manual plots of various devices frequency
response. The only time I ran into trouble was when I had to generate
a specific frequency tone, such as the Bell system test frequency of
1004Hz. I just connected a frequency counter and reset the dial every
time it tried to move.

Whether it's practical depends on what you are doing with it. What is
your application? If it's generating a 5MHz RF signal to radio
receiver, forget it. Not only is it not stable enough, but the AM and
FM noise produced by the function generator is truly awful.

But before throwing it in the waste basket (as I'll probably do in the end),

I think you'll find that it's a rather useful piece of equipment for
audio, not RF. I suggest you keep it (or sell it). Checking eBay
completed listings, they were recently sold from $70 to $150.
http://www.ebay.com/sch/i.html?_skipfnorm=1&_nkw=HP3312A&_in_kw=1&_ex_kw=& _sacat=0&_okw=&_oexkw=&_adv=1&LH_Complete=1&_udlo= &_udhi=&_samilow=&_samihi=&_sadis=200&_fpos=&_fsct =&LH_SALE_CURRENCY=0&_sop=12&_dmd=1&_ipg=50

I would be curious to know the experience of other people having that
generator or a similar one using the same (analog) frequency generation
principle (charging a capacitor at constant current). Do all of them behave
more or less the same? Is my unit faulty?

It's not faulty and all such analog instruments drift and are noisy.
Please disclose your application and I can offer a class of suitable
instruments, or a specific device that I like.

My (messy) bench:
http://802.11junk.com/jeffl/pics/home/slides/BL-shop6.html
I count 7 different signal sources on the bench. There are about 10
more scattered in different corners. One signal source just can't do
everything.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

"Jeff Liebermann" wrote in message
news
On Mon, 19 Mar 2012 22:42:47 +0100, "Antonio I0JX"
wrote:

Frequency measurement results a
- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz (drift = 6.5 kHz per minute)
- 30 minutes after. Delta F = - 116 kHz (drift = 3.7 kHz per minute)
- 45 minutes after. Delta F = -132 kHz (drift = 2.9 kHz per minute)
- 60 minutes after. Delta F = -141 kHz (drift = 2.3 kHz per minute)
- 75 minutes after. Delta F = -147 kHz (drift = 2.0 kHz per minute)

150KHz of 5000KHz is 3% drift. That's within the specified 5%.

Drift is too high for any practical use.

Really? I used a 3312A in the 1970's to do type certification on
various radios. It was perfectly suited for running as an audio sweep
generator, or for making manual plots of various devices frequency
response. The only time I ran into trouble was when I had to generate
a specific frequency tone, such as the Bell system test frequency of
1004Hz. I just connected a frequency counter and reset the dial every
time it tried to move.

Whether it's practical depends on what you are doing with it. What is
your application? If it's generating a 5MHz RF signal to radio
receiver, forget it. Not only is it not stable enough, but the AM and
FM noise produced by the function generator is truly awful.

But before throwing it in the waste basket (as I'll probably do in the
end),

I think you'll find that it's a rather useful piece of equipment for
audio, not RF. I suggest you keep it (or sell it). Checking eBay
completed listings, they were recently sold from $70 to $150.
http://www.ebay.com/sch/i.html?_skipfnorm=1&_nkw=HP3312A&_in_kw=1&_ex_kw=& _sacat=0&_okw=&_oexkw=&_adv=1&LH_Complete=1&_udlo= &_udhi=&_samilow=&_samihi=&_sadis=200&_fpos=&_fsct =&LH_SALE_CURRENCY=0&_sop=12&_dmd=1&_ipg=50

I would be curious to know the experience of other people having that
generator or a similar one using the same (analog) frequency generation
principle (charging a capacitor at constant current). Do all of them
behave
more or less the same? Is my unit faulty?

It's not faulty and all such analog instruments drift and are noisy.
Please disclose your application and I can offer a class of suitable
instruments, or a specific device that I like.

My (messy) bench:
http://802.11junk.com/jeffl/pics/home/slides/BL-shop6.html
I count 7 different signal sources on the bench. There are about 10
more scattered in different corners. One signal source just can't do
everything.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS


HTF do you work on that bench Jeff ? I thought my benches were a bloody
mess, but they are positively lab-standard compared to that !!!

Arfa

"Arfa Daily" wrote:
"Jeff Liebermann" wrote in message
news
On Mon, 19 Mar 2012 22:42:47 +0100, "Antonio I0JX"
wrote:

Frequency measurement results a
- Just turned on. Frequency = 5.000 MHz Delta F = 0
- 15 minutes after. Delta F = -98 kHz (drift = 6.5 kHz per minute)
- 30 minutes after. Delta F = - 116 kHz (drift = 3.7 kHz per minute)
- 45 minutes after. Delta F = -132 kHz (drift = 2.9 kHz per minute)
- 60 minutes after. Delta F = -141 kHz (drift = 2.3 kHz per minute)
- 75 minutes after. Delta F = -147 kHz (drift = 2.0 kHz per minute)

150KHz of 5000KHz is 3% drift. That's within the specified 5%.

Drift is too high for any practical use.

Really? I used a 3312A in the 1970's to do type certification on
various radios. It was perfectly suited for running as an audio sweep
generator, or for making manual plots of various devices frequency
response. The only time I ran into trouble was when I had to generate
a specific frequency tone, such as the Bell system test frequency of
1004Hz. I just connected a frequency counter and reset the dial every
time it tried to move.

Whether it's practical depends on what you are doing with it. What is
your application? If it's generating a 5MHz RF signal to radio
receiver, forget it. Not only is it not stable enough, but the AM and
FM noise produced by the function generator is truly awful.

But before throwing it in the waste basket (as I'll probably do in the end),

I think you'll find that it's a rather useful piece of equipment for
audio, not RF. I suggest you keep it (or sell it). Checking eBay
completed listings, they were recently sold from $70 to $150.
http://www.ebay.com/sch/i.html?_skipfnorm=1&_nkw=HP3312A&_in_kw=1&_ex_kw=& _sacat=0&_okw=&_oexkw=&_adv=1&LH_Complete=1&_udlo= &_udhi=&_samilow=&_samihi=&_sadis=200&_fpos=&_fsct =&LH_SALE_CURRENCY=0&_sop=12&_dmd=1&_ipg=50

I would be curious to know the experience of other people having that
generator or a similar one using the same (analog) frequency generation
principle (charging a capacitor at constant current). Do all of them behave
more or less the same? Is my unit faulty?

It's not faulty and all such analog instruments drift and are noisy.
Please disclose your application and I can offer a class of suitable
instruments, or a specific device that I like.

My (messy) bench:
http://802.11junk.com/jeffl/pics/home/slides/BL-shop6.html
I count 7 different signal sources on the bench. There are about 10
more scattered in different corners. One signal source just can't do
everything.

-- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS


HTF do you work on that bench Jeff ? I thought my benches were a bloody
mess, but they are positively lab-standard compared to that !!!

Arfa

I see some space. Everything within grabbing distance.

Greg

On Fri, 23 Mar 2012 01:23:20 -0000, "Arfa Daily"
wrote:

My (messy) bench:
http://802.11junk.com/jeffl/pics/home/slides/BL-shop6.html

HTF do you work on that bench Jeff ?

I think small. Most of the things I work on are small enough to fit
on what's left of the bench. Neatness is a sure sign of some
undesireable trait, although I don't recall what it might be at this
moment. Unfortunately, I now have a piece of unrepairable test
equipment scattered all over the bench, so all new projects have come
to a halt until it decides to allow itself to be fixed.

I thought my benches were a bloody
mess, but they are positively lab-standard compared to that !!!

It's been like that for about 35 years. Some day, I'll clean it up.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

Drift is too high for any practical use.

But before throwing it in the waste basket (as I'll probably do in the
end),

That's an emotional reaction. Would you be upset with your plow horse
because it didn't win the Kentucky Derby? It's all about matching
the tool to the task.

Don't throw it in the trash. I know a dozen people who'd love to have it.

"mike" ha scritto nel messaggio ...


Drift is too high for any practical use.

But before throwing it in the waste basket (as I'll probably do in the
end),

That's an emotional reaction. Would you be upset with your plow horse
because it didn't win the Kentucky Derby? It's all about matching
the tool to the task.

Don't throw it in the trash. I know a dozen people who'd love to have it.


I prefer to have a single generator that can serve all my needs, rather than
having many generators, one for each application. Too much room otherwise,
too many cables and plugs.

In practice this HP generator is only good for audio applications. At IF
(455 kHz) it requires being re-tuned frequently to stay on frequency. At HF
(10 MHz) I cannot figure out an application that tolerates that frequency
instability.

I had other function generators in the past, but I do not recall having such
a high instability. That is why I suspect mine has some problem.

Better buy a DDS at an affordable cost.

Regards.

Tony

"Antonio I0JX = radio ham fool "

"mike"
Don't throw it in the trash. I know a dozen people who'd love to have it.


I prefer to have a single generator that can serve all my needs, rather
than having many generators, one for each application.

** There ain't no such animal - you narcissistic imbecile.

In practice this HP generator is only good for audio applications.


** It's good for any application from 0.01Hz to 12MHz that does NOT require
a high level of frequency stability.


At IF (455 kHz) it requires being re-tuned frequently to stay on
frequency. At HF (10 MHz) I cannot figure out an application that
tolerates that frequency instability.

** Only shows how pig ignorant you are.


I had other function generators in the past, but I do not recall having
such a high instability.

** Absence of memory makes the heart grow fonder ?


That is why I suspect mine has some problem.

** You are one stubborn ****er.

**** off.


...... Phil