? How to stabilize a cheap colpitts oscillator

[Phil Allison]

"Dave"

I may be ignorant, but I am sincere. The resistor feeds the input cable
to the counter.

** Bullshit.

There would be virtually NO SIGNAL left at the counter's input.

100 kohms into a 50pF load at 6.5 MHz = 50 dB attenuation !!!!!!!!

Can you read resistor colour codes ?

I'll see what I can do about a JPEG of the setup and test equipment. That
will have to wait until tomorrow however. It's tired and I'm late.

** Sure about the model number of that mysterious " Schlumberger 1252 "
counter ?

The Schlumberger 1250 and 1254 are both spectrum analysers.



......... Phil

 

[Dave]

"Dave"


** Bullshit.

There would be virtually NO SIGNAL left at the counter's input.

100 kohms into a 50pF load at 6.5 MHz = 50 dB attenuation !!!!!!!!

Can you read resistor colour codes ?





** Sure about the model number of that mysterious " Schlumberger 1252 "
counter ?

The Schlumberger 1250 and 1254 are both spectrum analysers.



........ Phil

I can read resistor color codes, and I can read the display of my DMM which
confirms the value of the resistor in question (I checked it before using
it, just to make sure). So far as the model of the frequency counter, 1252
is what it says on the front, and I can't argue with that.

BTW, I solved the mystery. Problem was where I was feeding the counter
from, which was the tank circuit of the active antenna. Moved the input for
the counter to the output of the oscillator, and problem is solved. Display
is now rock steady. Like I said, I may be ignorant, but I am sincere.

Call me an idiot if you like, but I'm beginning to think you are the troll
in this equation. Lots more accusations than answers. I do appreciate your
making me think, which is what I needed, but I have grow tired of the
body-slams. Sue me. I never claimed to be a genius.

Dave

 

[Bob]

Call me an idiot if you like, but I'm beginning to think you are the troll
in this equation. Lots more accusations than answers. I do appreciate
your making me think, which is what I needed, but I have grow tired of the
body-slams. Sue me. I never claimed to be a genius.

Dave

Dave,

You have to excuse Phil. He gets a little irritable and bloated around this
time of every month.

Bob

 

[Dave]

Dave,

You have to excuse Phil. He gets a little irritable and bloated around
this time of every month.

Bob

LOL!!! Thank you. I needed that. (still grinning...)

Dave

 

[Phil Allison]

"Dave the Drongo "

I can read resistor color codes, and I can read the display of my DMM
which confirms the value of the resistor in question (I checked it before
using it, just to make sure).

** The whole 100 kohms story is complete bollocks.

So far as the model of the frequency counter, 1252 is what it says on the
front, and I can't argue with that.

** Funny how no mention of it *at all* via Google.

BTW, I solved the mystery.

** No you have not.

Problem was where I was feeding the counter from, which was the tank
circuit of the active antenna.

** You claimed there was a 2 volt, clean signal at that spot.

You have no cred left.

Like I said, I may be ignorant, but I am sincere.

** You are a total BULLSHIT ARTIST !!

Call me an idiot if you like,

** You are an IDIOT.


**** Off.




........ Phil

 

[Phil Allison]

"Boob"



** Another ASD fucked imbecile.






........ Phil

 

[Dave]

"Boob"



** Another ASD fucked imbecile.






....... Phil

Whatever.

Goodnight.

 

[Bob]

** You are an IDIOT.


**** Off.

....... Phil

Phil,

You MUST remember to take your Midol, sweetheart.

http://www.emedicinehealth.com/premenstrual_syndrome_pms/article_em.htm

Bob

 

[Fred Bartoli]

Phil Allison a écrit :

"Dave"


** Course it is the problem.





** The counter needs to see a clean input signal ( not one full of
harmonics) with sufficient amplitude - likely at least 100mV.

Oh, I thought counters should be able to count pulses, square waves...
Obviously I was mistaken.

 

[John Larkin]

Phil Allison a écrit :

Oh, I thought counters should be able to count pulses, square waves...
Obviously I was mistaken.

Counters should be able to count any reasonable waveform. A good
"universal" counter will have an adjustable threshold, ac/dc coupling,
and often a switchable attenuator. Cheaper counters, without
adjustments, can get confused by duty cycles, amplitude variation, and
things like ringing and noise.

John

 

[YD]

A spec for the counter? No, it's old and I got it used. Would a tank
circuit produce a signal full of harmonics? I somehow thought it would be
fairly clean... And 100 mV shouldn't be a problem, I don't think. The
scope shows a 2v signal peak to peak.

Thanks,

Dave

The counter is sensitive to below and above some reference level and
counts those transitions. What does it look like on the scope? It
doesn't need to be a pure sinewave, as long as there aren't any
obvious wiggles or noise. Try checking the counter with a known good
generator.

- YD.

 

[Rich Grise]

I apologize, the freq counter is a Schlumberger 1252, and the scope is a
Tek 2335 100MHz dual-trace, but I am only using one channel. I honestly
don't kow what else to tell you about the test equipment. Do not mean to
be tedious. I am just a hobbyist. I used to repair computers, but that
was 15 years ago, and I am just getting back into the groove.

Don't worry too much about Phil - sometimes he goes off his meds.

What does the counter say when you clip it to the scope's calibrator?

Thanks,
Rich

 

[Fred Bartoli]

John Larkin a écrit :

Counters should be able to count any reasonable waveform. A good
"universal" counter will have an adjustable threshold, ac/dc coupling,
and often a switchable attenuator. Cheaper counters, without
adjustments, can get confused by duty cycles, amplitude variation, and
things like ringing and noise.

He he, it wasn't your leg I was pulling
(unless you were not answering me)

 

[Jamie]

I honestly wondered about the counter as a possible source of the problem.
A trigger threshold problem would explain this perfectly in my mind. The
scope shows a stable 5 to 10 MHz, (depending on what I dial up with the
tuning cap in the Colpitts) while the counter says anything between 1 and
6.7 MHz no matter what the scope shows. Any ideas on how I could
troubleshoot the counter? I've got a lot more time than money...

Thanks,

Dave

put a simply unity gain follower amp on the output.. something like an
emitter follower.

 

[Zak]

Dave wrote:

put a simply unity gain follower amp on the output.. something like an
emitter follower.

Or a CMOS amplifier (74HCU04 with resistior from input to output).


Thomas

 

[Phil Allison]

"Fred Bartoli Frog Moron "

Oh, I thought counters should be able to count pulses, square waves...
Obviously I was mistaken.

** A square wave IS a clean signal - there are only 2 zero crossings per
cycle, so no false counting problem.

Other waveforms with strong harmonics of the fundamental frequency may well
exhibit extra zero crossings and these also become added to the count.

Users of frequency counters need to be aware of the problem and check the
input signal with a scope if anomalous readings are being obtained.


BTW Fred,

Your mistakes are all too obvious & your asinine ignorance is beyond the
tiniest doubt.

**** off.



........ Phil

 

[Dave]

Counters should be able to count any reasonable waveform. A good
"universal" counter will have an adjustable threshold, ac/dc coupling,
and often a switchable attenuator. Cheaper counters, without
adjustments, can get confused by duty cycles, amplitude variation, and
things like ringing and noise.

John

Hey everyone...

Turns out the problem with the counter was where I was taking the input
from, which was the tank circuit of the active antenna. Taking the input
from the output of the signal generator fixed the wild fluctuations. Rock
steady. And rewinding the coils gives me a Q of 231 for the first, which
had a Q of 177 last night, and nearly 400 for the second, which previously
was something like 4. I honestly find this value hard to believe, but
that's what it looks like.

Don't know what else to say right now. Once that problem was resolved,
everything else sort of fell into place...

Regards,

Dave

 

[John Larkin]

John Larkin a écrit :

He he, it wasn't your leg I was pulling
(unless you were not answering me)

Repeat after me:

IRONY DOES NOT WORK ON USENET
IRONY DOES NOT WORK ON USENET
IRONY DOES NOT WORK ON USENET
IRONY DOES NOT WORK ON USENET
IRONY DOES NOT WORK ON USENET
IRONY DOES NOT WORK ON USENET

John

 

[Michael A. Terrell]

Yes, the scope and counter are connected simultaneously. That's why I
wondered about the counter...

Dave, does your tek scope have a "Ch 2 output on the rear panel? If
it does, you need to connect your counter there with a BNC cable, to
whatever the freq counter's input takes.



--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[amdx]

Dave, does your tek scope have a "Ch 2 output on the rear panel? If
it does, you need to connect your counter there with a BNC cable, to
whatever the freq counter's input takes.

On my scope it's CH 1 output. (Hitachi)
Mike