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spectrogram

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n3drk

spectrogram

In addition to aligning the IF's for the K2 can Spectrogram also show the
Christmas Tree effect for SSB? How about the rise and fall of the CW note?
What about in receive mode. Can it also show these for the received station?
73s

john-n3drk

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ab4cz

Re: spectrogram

John,

Sjpectrogram is a FFT (Fast Fourier Transform) spectrum analyzer program. It's display is amplitude versus frequency. What you need to display the "Christmas Tree" and CW waveforms is an oscilloscope display. In the case of the Christmas Tree, the oscilloscope is set up to display RF drive or audio on the horizontal axis and RF output on the vertical axis (the oscilloscope is in X-Y mode, with x=drive, Y=RF out). For the cw envelope you use the oscilloscope in the conventional mode where the horizontal axis is time and the vertical axis is voltage. So the short answer to your question is "NO".

jim, AB4CZ

>can Spectrogram also show the
>Christmas Tree effect for SSB? How about the rise and fall of the CW note?
>What about in receive mode. Can it also show these for the received station?
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Don Wilhelm-3

RE: spectrogram

In reply to this post by n3drk

John,

No - what you are asking about is a time-domain display as you would see on
an oscilloscope, Spectrogram provides a frequency-domain display by
computing the FFT of the input signal - i.e. Spectrogram is a spectrum
analyzer, but it is limited to audio frequencies.

73,
Don W3FPR

> -----Original Message-----

>
> In addition to aligning the IF's for the K2 can Spectrogram also show the
> Christmas Tree effect for SSB? How about the rise and fall of the CW note?
> What about in receive mode. Can it also show these for the
> received station?
> 73s
>
> john-n3drk
>
>

n3drk

Re: spectrogram

In reply to this post by ab4cz

Listed below is a link for a Windows based Oscilloscope. This can be used
for transmitting but I do not know about receiving. What do you guys think?
By the way thanks to all for responding to my original post.

http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3428

73s
john-n3drk

----- Original Message -----
From: <[hidden email]>
To: "n3drk" <[hidden email]>; "elecraft" <[hidden email]>
Sent: Sunday, January 22, 2006 9:31 AM
Subject: Re: [Elecraft] spectrogram

>
> John,
>
> Sjpectrogram is a FFT (Fast Fourier Transform) spectrum analyzer program.
> It's display is amplitude versus frequency. What you need to display the
> "Christmas Tree" and CW waveforms is an oscilloscope display. In the
> case of the Christmas Tree, the oscilloscope is set up to display RF drive
> or audio on the horizontal axis and RF output on the vertical axis (the
> oscilloscope is in X-Y mode, with x=drive, Y=RF out). For the cw envelope
> you use the oscilloscope in the conventional mode where the horizontal
> axis is time and the vertical axis is voltage. So the short answer to
> your question is "NO".
>
> jim, AB4CZ
>
>>can Spectrogram also show the
>>Christmas Tree effect for SSB? How about the rise and fall of the CW note?
>>What about in receive mode. Can it also show these for the received
>>station?
>

Tom Hammond-3

Re: spectrogram

Any time you use an audio-based oscilloscope, monitoring the AF
output from your receiver, you have to be aware that whatever you see
on-screen is not only representative of the signal itself BUT to a
bigger extent it reflects those characteristics placed upon it by the
receiver itself (it's filters, the AGC characteristics, etc.). As a
result, you should always remind yourself that what you're looking at
(if it's coming thru the receiver's audio system) is not necessarily
what is actually 'on the air'.

73,

Tom Hammond N0SS

At 11:55 AM 1/22/2006, n3drk wrote:

>Listed below is a link for a Windows based Oscilloscope. This can be
>used for transmitting but I do not know about receiving. What do you
>guys think? By the way thanks to all for responding to my original post.
>
>http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3428
>
>
>73s
>john-n3drk
>
>
>----- Original Message ----- From: <[hidden email]>
>To: "n3drk" <[hidden email]>; "elecraft" <[hidden email]>
>Sent: Sunday, January 22, 2006 9:31 AM
>Subject: Re: [Elecraft] spectrogram
>
>
>>
>>John,
>>
>>Sjpectrogram is a FFT (Fast Fourier Transform) spectrum analyzer
>>program. It's display is amplitude versus frequency. What you need
>>to display the "Christmas Tree" and CW waveforms is
>>an oscilloscope display. In the case of the Christmas Tree, the
>>oscilloscope is set up to display RF drive or audio on the
>>horizontal axis and RF output on the vertical axis (the
>>oscilloscope is in X-Y mode, with x=drive, Y=RF out). For the cw
>>envelope you use the oscilloscope in the conventional mode where
>>the horizontal axis is time and the vertical axis is voltage. So
>>the short answer to your question is "NO".
>>
>>jim, AB4CZ
>>
>>>can Spectrogram also show the
>>>Christmas Tree effect for SSB? How about the rise and fall of the CW note?
>>>What about in receive mode. Can it also show these for the received station?
>
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
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>
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>Elecraft web page: http://www.elecraft.com

n3drk

Re: spectrogram

Great point Tom. Thanks.
john

----- Original Message -----
From: "Tom Hammond" <[hidden email]>
To: "n3drk" <[hidden email]>; <[hidden email]>; "elecraft"
<[hidden email]>
Sent: Sunday, January 22, 2006 3:30 PM
Subject: Re: [Elecraft] spectrogram

> Any time you use an audio-based oscilloscope, monitoring the AF output
> from your receiver, you have to be aware that whatever you see on-screen
> is not only representative of the signal itself BUT to a bigger extent it
> reflects those characteristics placed upon it by the receiver itself (it's
> filters, the AGC characteristics, etc.). As a result, you should always
> remind yourself that what you're looking at (if it's coming thru the
> receiver's audio system) is not necessarily what is actually 'on the air'.
>
> 73,
>
> Tom Hammond N0SS
>
> At 11:55 AM 1/22/2006, n3drk wrote:
>>Listed below is a link for a Windows based Oscilloscope. This can be used
>>for transmitting but I do not know about receiving. What do you guys
>>think? By the way thanks to all for responding to my original post.
>>
>>http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3428
>>
>>
>>73s
>>john-n3drk
>>
>>
>>----- Original Message ----- From: <[hidden email]>
>>To: "n3drk" <[hidden email]>; "elecraft" <[hidden email]>
>>Sent: Sunday, January 22, 2006 9:31 AM
>>Subject: Re: [Elecraft] spectrogram
>>
>>
>>>
>>>John,
>>>
>>>Sjpectrogram is a FFT (Fast Fourier Transform) spectrum analyzer program.
>>>It's display is amplitude versus frequency. What you need to display the
>>>"Christmas Tree" and CW waveforms is an oscilloscope display. In the
>>>case of the Christmas Tree, the oscilloscope is set up to display RF
>>>drive or audio on the horizontal axis and RF output on the vertical axis
>>>(the oscilloscope is in X-Y mode, with x=drive, Y=RF out). For the cw
>>>envelope you use the oscilloscope in the conventional mode where the
>>>horizontal axis is time and the vertical axis is voltage. So the short
>>>answer to your question is "NO".
>>>
>>>jim, AB4CZ
>>>
>>>>can Spectrogram also show the
>>>>Christmas Tree effect for SSB? How about the rise and fall of the CW
>>>>note?
>>>>What about in receive mode. Can it also show these for the received
>>>>station?
>>
>>_______________________________________________
>>Elecraft mailing list
>>Post to: [hidden email]
>>You must be a subscriber to post to the list.
>>Subscriber Info (Addr. Change, sub, unsub etc.):
>>http://mailman.qth.net/mailman/listinfo/elecraft
>>
>>Help: http://mailman.qth.net/subscribers.htm
>>Elecraft web page: http://www.elecraft.com

ab4cz

Re: spectrogram

In reply to this post by n3drk

John,
I didn't see any other responses to this so I thought I'd jump in again. The PC-based oscilloscope using a sound card is severly limited in bandwidth. The typical sound card will limit your bandwidth to about 20Khz, which is hardly even sufficient for audio work and totally useless for RF. Whle this is a handy toy for working on low frequency and audio stuff, it's hardly an "oscilloscope". If you want a scope, look at a big hamfest or on e-Bay. You can frequently find 50MHz scopes (sufficient for most ham work) for under $100. There are also some PC-based scopes that have the "oscilloscope" in a box and connect to a PC through a parallel port or USB and use the scope for processing and display. I have one such scope ... a PICO 3206 ... that works really fine and gives the advantage of allowing cut and paste of scope images into documentation. PICO and others have a range bandwidth and resolution available for almost any application, and the prices are less than a comp
arable Tektronix or LeCroy.

If your main interest is in looking at your transmitted waveforms (keying envelope and "christmas tree", you will be best served by a monitor scope such as the old Heath or Kenwood. These not useful as general purpose oscilloscopes but work great at their intended purpose ... to monitor transmitters. I have the Heath SB-614 I bought at a Hamfest about 24 years ago. Personally, I think it should be a REQUIREMENT that anyone with a high power amplifier have a monitor scope. It's the best way to be assured your amplifier is tuned properly for best linearity. I don't know if anyone is building a modern equivalent of the SB-614 or the Kenwood (model #?).

Try a Google search for PC OSCILLOSCOPES and you will find a bunch of them available.

By the way, several of the PC scopes double as a low-end spectrum analyzer. The PICO 3206 has a 200 MHz analog bandwidth and also a 200MSample/Second single-shot sample rate. It performs as a 100 MHz spectrum analyzer using FFT (Fast Fourier Transform) similar to Spectrascope.

Good luck with your search for a scope display. By the way, I just did an e-Bay search for "oscilloscope" and got more than 13 pages of listings, some in the $40 range. If all you want is a transmitter monitor, you can probably get by with a 20 MHz scope and couple RF output directly to the vertical deflection plates. If you need more information, let me know exactly what you are trying to do. I can probably give you some more marginally useless advice.

regards,

Jim
AB4CZ

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Ron D'Eau Claire-2

Oscilloscopes (WAS: spectrogram)

Jim, AB4CZ gave you an excellent summary.

If you think you'd like to use the 'scope for general bench work to look at
waveforms, etc., on HF gear, then look for one with at least a 200 MHz
bandwidth.

Smaller bandwidth scopes are fine for a simple check on your transmitter
waveform, but one of the greatest advantages to a scope is being able to see
things you can't see otherwise - parasitics, the transition waveforms when
keying, edges of clock signals, etc. While the fundamental frequency of the
waveform may only be a few MHz, the frequency of the squiggles and other
artifacts on the signal is much, much higher. For those applications a
general 'rule of thumb' is to use a 'scope with at least 10 times the
highest frequency you'll be interested in, the higher the better.

If you try to observe signals on a narrower bandwidth oscilloscope, the
higher-frequency information is simply lost. The displayed waveform will
look much cleaner that it really is! For example, if you try to observe a 50
MHz square wave on a 50 MHz oscilloscope it'll show you a nice, clean sine
wave, not a square wave. All of the higher-frequency information that makes
the edges of the square wave sharp will be lost. To get a decent
representation of the actual waveform you'd need at least a 500 MHz
oscilloscope.

At today's Hamfest prices, the price difference between a basic waveform
monitor and a good general purpose scope is often small, and with the latter
you have an instrument that will prove itself quite valuable over time if
you enjoy tinkering with circuits on the bench.

Ron AC7AC

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Alexandra Carter

Re: Oscilloscopes (WAS: spectrogram)

Tektronix 475, baby! The 465 is OK, and the 485 a real 400MHz work of
analog scope art I hope to own someday. Then if you're really serious
you have a 7000-series mainframe and a lot of plugins hehe.

A really good tutorial on scopes is Tektronix's The XYZ's Of Using A
Scope which they used to give out, now you can download it from the net
and the recent versions have a bunch of stupid stuff about their
digital scopes - they tell such beautiful lies, stick to analog.

73 de Alex NS6Y.

On Jan 23, 2006, at 7:06 PM, Ron D'Eau Claire wrote:

> Jim, AB4CZ gave you an excellent summary.
>
> If you think you'd like to use the 'scope for general bench work to
> look at
> waveforms, etc., on HF gear, then look for one with at least a 200 MHz
> bandwidth. ...........If you try to observe signals on a narrower
> bandwidth oscilloscope, the
> higher-frequency information is simply lost.....
> At today's Hamfest prices, the price difference between a basic
> waveform
> monitor and a good general purpose scope is often small....,
> Ron AC7AC

Ron D'Eau Claire-2

RE: Oscilloscopes (WAS: spectrogram)

Alex NS6Y wrote:

Tektronix 475, baby! The 465 is OK, and the 485 a real 400MHz work of
analog scope art I hope to own someday...

--------------------------

Yep, Tek scopes are the most popular and they are very good. In the 1970's
when I was running a television production studio we had to smuggle in our
Tek waveform monitors because the facility was owned by Hewlett-Packard!

Hewlett-Packard scopes are also EXCELLENT instruments though - at least
their general-purpose lab scopes, which is what I was talking about here.
When I was working in various labs I liked Tek scopes primarily because of
their extreme flexibility, thanks to all of those expensive plug-ins <G>,
and because they carefully kept the control layout much the same from model
to model. Grab that big knob over there and it was always the time base
control, no matter which Tek scope you were using.

HP wasn't so consistent with their panel layouts and they don't have all the
swappable plug-ins that Tek used. However, HP made its name as a lab
instrument company for almost 40 years before they touched the computer
business in the 1970's with world-class lab gear. One advantage of their
'scopes for the Ham today is that they are often a lot cheaper than the Tek
scopes, feature for feature and per megacycle of bandwidth simple because
the Tek scopes are so popular.

I have an HP1740 sitting on my bench that was built in the 1970's. It's an
analog scope, which I prefer, and it's still tickin' like the day it was
built, almost 40 years later!

Ron AC7AC

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srife

Re: Oscilloscopes (WAS: spectrogram)

I have a 475 with the DM44 option, and a scad of different probes.
It is on "semi-permanent" loan from my company (they have no need for it
any longer). I have never used the DM44, but what looks interesting is
that it will measure temperature in degrees C. I have the temperature
probe and will get around to trying that out one of these days. I have
never used an oscilloscope before about a couple of months ago, but I am
trying to learn. The tutorial that Tek has on their website is pretty
informative.

Stan Rife
W5EWA

Ron D'Eau Claire wrote:

> Alex NS6Y wrote:
>
> Tektronix 475, baby! The 465 is OK, and the 485 a real 400MHz work of
> analog scope art I hope to own someday...
>
> --------------------------
>
> Yep, Tek scopes are the most popular and they are very good. In the 1970's
> when I was running a television production studio we had to smuggle in our
> Tek waveform monitors because the facility was owned by Hewlett-Packard!
>
> Hewlett-Packard scopes are also EXCELLENT instruments though - at least
> their general-purpose lab scopes, which is what I was talking about here.
> When I was working in various labs I liked Tek scopes primarily because of
> their extreme flexibility, thanks to all of those expensive plug-ins <G>,
> and because they carefully kept the control layout much the same from model
> to model. Grab that big knob over there and it was always the time base
> control, no matter which Tek scope you were using.
>
> HP wasn't so consistent with their panel layouts and they don't have all the
> swappable plug-ins that Tek used. However, HP made its name as a lab
> instrument company for almost 40 years before they touched the computer
> business in the 1970's with world-class lab gear. One advantage of their
> 'scopes for the Ham today is that they are often a lot cheaper than the Tek
> scopes, feature for feature and per megacycle of bandwidth simple because
> the Tek scopes are so popular.
>
> I have an HP1740 sitting on my bench that was built in the 1970's. It's an
> analog scope, which I prefer, and it's still tickin' like the day it was
> built, almost 40 years later!
>
> Ron AC7AC
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>

Don Brown-4

Re: Oscilloscopes (WAS: spectrogram)

In reply to this post by Alexandra Carter

Hi

Be careful buying older Tek scopes. Many of the repair parts are not
available any more. You may get lucky and never need to repair one of these
scopes but many of the parts were proprietary made custom for Tek or in the
case of some of the IC's and CRT's were made only by Tek in there own fab. I
worked for Tektronix for many years as a field maintenance instructor in the
test and measurement division. My specialty was the 7000 series and the
portable scopes among others. The reason the 7000 series is so cheap on Ebay
is the problem of getting repair parts. The most common problem is with the
cam switches and attenuators in both the 7000 and the 465 and 475 scopes.
The 485 is even a generation earlier than the 465 or 475 so I would not ever
consider one these scopes unless it had a good CRT, is in excellent
condition and was virtually free. It also takes a real expert and some
special equipment to properly tweak a 485 so it will meet specs. The 7000
series may be OK if you can buy two for a few hundred dollars. The second
one for parts. I have a friend with a cal lab that has a warehouse full of
broken 7000's that he uses for parts to keep the stuff he has under
contract. Tek has a policy that they do not guarantee parts support seven
years after a product is discontinued. The 465, 475 and most of the 7000 has
exceeded that by two and the 485 by three

However I personally own a 2465 and can highly recommend it. It is 400 Mhz
four channel with both 1 meg ohm and 50 ohm inputs with dual timebase. This
was the last of the really great analog scopes Tek made. This scope sold for
over $5000 in the mid 80's and was worth every penny. I have seen them on
Ebay for well under $1000 (I paid $800 for mine a couple of years ago) I
know that is a lot of money to spend on a scope used for hobby work but a
new scope with much less capability will cost as much or more.

Ron Is correct on the bandwidth specification. Scopes are rated at 3 db down
at the rated bandwidth. This means a 100 MHz scope can measure a one volt pk
to pk 100 MHz sine wave at .707 volts and still be in spec. Also the probes
are rated at a max bandwidth as well. If you use a 100 MHz probe on a 200
MHz scope then you will only have a 100 Mhz bandwidth at best

Don Brown
KD5NDB

----- Original Message -----
From: "Alexandra Carter" <[hidden email]>
To: "Ron D'Eau Claire" <[hidden email]>
Cc: <[hidden email]>
Sent: Monday, January 23, 2006 9:13 PM
Subject: Re: [Elecraft] Oscilloscopes (WAS: spectrogram)

> Tektronix 475, baby! The 465 is OK, and the 485 a real 400MHz work of
> analog scope art I hope to own someday. Then if you're really serious
> you have a 7000-series mainframe and a lot of plugins hehe.
>
> A really good tutorial on scopes is Tektronix's The XYZ's Of Using A
> Scope which they used to give out, now you can download it from the net
> and the recent versions have a bunch of stupid stuff about their
> digital scopes - they tell such beautiful lies, stick to analog.
>
> 73 de Alex NS6Y.
>
> On Jan 23, 2006, at 7:06 PM, Ron D'Eau Claire wrote:
>
> > Jim, AB4CZ gave you an excellent summary.
> >
> > If you think you'd like to use the 'scope for general bench work to
> > look at
> > waveforms, etc., on HF gear, then look for one with at least a 200 MHz
> > bandwidth. ...........If you try to observe signals on a narrower
> > bandwidth oscilloscope, the
> > higher-frequency information is simply lost.....
> > At today's Hamfest prices, the price difference between a basic
> > waveform
> > monitor and a good general purpose scope is often small....,
> > Ron AC7AC
>
> _______________________________________________

Don Brown-4

Re: Oscilloscopes (WAS: spectrogram)

In reply to this post by srife

Hi

In interesting piece of trivia. The DM44 sensor in the temperature probe is
a 2n2222 transistor. The circuit is similar to the temperature measuring
circuit in the KPA100 used to monitor the heat sink temperature.

Don Brown

KD5NDB

----- Original Message -----
From: "Stan Rife" <[hidden email]>
To: <[hidden email]>
Sent: Monday, January 23, 2006 9:56 PM
Subject: Re: [Elecraft] Oscilloscopes (WAS: spectrogram)

> I have a 475 with the DM44 option, and a scad of different probes.
> It is on "semi-permanent" loan from my company (they have no need for it
> any longer). I have never used the DM44, but what looks interesting is
> that it will measure temperature in degrees C. I have the temperature
> probe and will get around to trying that out one of these days. I have
> never used an oscilloscope before about a couple of months ago, but I am
> trying to learn. The tutorial that Tek has on their website is pretty
> informative.
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
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Elecraft web page: http://www.elecraft.com

Alexandra Carter

Re: Oscilloscopes (WAS: spectrogram)

In reply to this post by Don Brown-4

Yes, but in actuality, you can very often pick up a good 465 or 475 for
$100 or so, take it home, clean it up, and it will work for you for
years. That's hard to beat. 73 de Alex NS6Y.

On Jan 23, 2006, at 8:36 PM, Don Brown wrote:

> Hi
>
> Be careful buying older Tek scopes. Many of the repair parts are not
> available any more. You may get lucky and never need to repair one of
> these
> scopes but many of the parts were proprietary made custom for Tek or
> in the
> case of some of the IC's and CRT's were made only by Tek in there own
> fab. I
> worked for Tektronix for many years as a field maintenance instructor
> in the
> test and measurement division. My specialty was the 7000 series and the
> portable scopes among others. The reason the 7000 series is so cheap
> on Ebay
> is the problem of getting repair parts. The most common problem is
> with the
> cam switches and attenuators in both the 7000 and the 465 and 475
> scopes.
> The 485 is even a generation earlier than the 465 or 475 so I would
> not ever
> consider one these scopes unless it had a good CRT, is in excellent
> condition and was virtually free. It also takes a real expert and some
> special equipment to properly tweak a 485 so it will meet specs. The
> 7000
> series may be OK if you can buy two for a few hundred dollars. The
> second
> one for parts. I have a friend with a cal lab that has a warehouse
> full of
> broken 7000's that he uses for parts to keep the stuff he has under
> contract. Tek has a policy that they do not guarantee parts support
> seven
> years after a product is discontinued. The 465, 475 and most of the
> 7000 has
> exceeded that by two and the 485 by three
>
> However I personally own a 2465 and can highly recommend it. It is 400
> Mhz
> four channel with both 1 meg ohm and 50 ohm inputs with dual timebase.
> This
> was the last of the really great analog scopes Tek made. This scope
> sold for
> over $5000 in the mid 80's and was worth every penny. I have seen them
> on
> Ebay for well under $1000 (I paid $800 for mine a couple of years ago)
> I
> know that is a lot of money to spend on a scope used for hobby work
> but a
> new scope with much less capability will cost as much or more.
>
> Ron Is correct on the bandwidth specification. Scopes are rated at 3
> db down
> at the rated bandwidth. This means a 100 MHz scope can measure a one
> volt pk
> to pk 100 MHz sine wave at .707 volts and still be in spec. Also the
> probes
> are rated at a max bandwidth as well. If you use a 100 MHz probe on a
> 200
> MHz scope then you will only have a 100 Mhz bandwidth at best
>
>
>
> Don Brown
> KD5NDB
>
>
>
>
> ----- Original Message -----
> From: "Alexandra Carter" <[hidden email]>
> To: "Ron D'Eau Claire" <[hidden email]>
> Cc: <[hidden email]>
> Sent: Monday, January 23, 2006 9:13 PM
> Subject: Re: [Elecraft] Oscilloscopes (WAS: spectrogram)
>
>
>> Tektronix 475, baby! The 465 is OK, and the 485 a real 400MHz work of
>> analog scope art I hope to own someday. Then if you're really serious
>> you have a 7000-series mainframe and a lot of plugins hehe.
>>
>> A really good tutorial on scopes is Tektronix's The XYZ's Of Using A
>> Scope which they used to give out, now you can download it from the
>> net
>> and the recent versions have a bunch of stupid stuff about their
>> digital scopes - they tell such beautiful lies, stick to analog.
>>
>> 73 de Alex NS6Y.
>>
>> On Jan 23, 2006, at 7:06 PM, Ron D'Eau Claire wrote:
>>
>>> Jim, AB4CZ gave you an excellent summary.
>>>
>>> If you think you'd like to use the 'scope for general bench work to
>>> look at
>>> waveforms, etc., on HF gear, then look for one with at least a 200
>>> MHz
>>> bandwidth. ...........If you try to observe signals on a narrower
>>> bandwidth oscilloscope, the
>>> higher-frequency information is simply lost.....
>>> At today's Hamfest prices, the price difference between a basic
>>> waveform
>>> monitor and a good general purpose scope is often small....,
>>> Ron AC7AC
>>
>> _______________________________________________
>

srife

RE: Oscilloscopes (WAS: spectrogram)

In reply to this post by Don Brown-4

The 475 I have is working well, so far. Have not noticed any
problems. When I brought it home I turned it on and let it run for 3 days
straight. I wanted to see if it was going to have any power supply problems
right up front.
I keep the trace just bright enough to see well, when I am using it.
It has an orange colored backlight for the scale that really helps bring
that out, as well.
The ones I have seen for sale, are asking a whole lot more than
FREE, Don. If you know of any for free, let me know where and I'll go pick
'em up.

Stan Rife
W5EWA
Houston, TX
K2 S/N 4216

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Brown
Sent: Monday, January 23, 2006 10:36 PM
To: Ron D'Eau Claire; Alexandra Carter
Cc: [hidden email]
Subject: Re: [Elecraft] Oscilloscopes (WAS: spectrogram)

Hi

Be careful buying older Tek scopes. Many of the repair parts are not
available any more. You may get lucky and never need to repair one of these
scopes but many of the parts were proprietary made custom for Tek or in the
case of some of the IC's and CRT's were made only by Tek in there own fab. I

worked for Tektronix for many years as a field maintenance instructor in the

test and measurement division. My specialty was the 7000 series and the
portable scopes among others. The reason the 7000 series is so cheap on Ebay

is the problem of getting repair parts. The most common problem is with the
cam switches and attenuators in both the 7000 and the 465 and 475 scopes.
The 485 is even a generation earlier than the 465 or 475 so I would not ever

consider one these scopes unless it had a good CRT, is in excellent
condition and was virtually free. It also takes a real expert and some
special equipment to properly tweak a 485 so it will meet specs. The 7000
series may be OK if you can buy two for a few hundred dollars. The second
one for parts. I have a friend with a cal lab that has a warehouse full of
broken 7000's that he uses for parts to keep the stuff he has under
contract. Tek has a policy that they do not guarantee parts support seven
years after a product is discontinued. The 465, 475 and most of the 7000 has

exceeded that by two and the 485 by three

However I personally own a 2465 and can highly recommend it. It is 400 Mhz
four channel with both 1 meg ohm and 50 ohm inputs with dual timebase. This
was the last of the really great analog scopes Tek made. This scope sold for

over $5000 in the mid 80's and was worth every penny. I have seen them on
Ebay for well under $1000 (I paid $800 for mine a couple of years ago) I
know that is a lot of money to spend on a scope used for hobby work but a
new scope with much less capability will cost as much or more.

Ron Is correct on the bandwidth specification. Scopes are rated at 3 db down

at the rated bandwidth. This means a 100 MHz scope can measure a one volt pk

to pk 100 MHz sine wave at .707 volts and still be in spec. Also the probes
are rated at a max bandwidth as well. If you use a 100 MHz probe on a 200
MHz scope then you will only have a 100 Mhz bandwidth at best

Don Brown
KD5NDB

----- Original Message -----
From: "Alexandra Carter" <[hidden email]>
To: "Ron D'Eau Claire" <[hidden email]>
Cc: <[hidden email]>
Sent: Monday, January 23, 2006 9:13 PM
Subject: Re: [Elecraft] Oscilloscopes (WAS: spectrogram)

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ab4cz

RE: Oscilloscopes (WAS: spectrogram)

In reply to this post by Ron D'Eau Claire-2

Poor John asked if he could use spectrogram as an oscilloscope, and that's morphed into recommendations to buy a 400 MHz scope! In my last job I was the video amplifier design guy, and in that role I designed video amplifiers to drive CRTs in high-resolution industrial computer displays. Over the years, resolution requirements constantly increased so the last generations of products had CRT cathode drive requirements on the order of 60Vp-p with <3nSec rise and fall times. As I recall, the last video amp I did was around 2.7nSec at 60 Volts drive. (now you know why CRT monitors can cause serious RFI ... shielding was one of the biggest challenges). My point is, I am familiar with and appreciate the need for fast oscilloscopes when the application requires it . My favorite was the 475 until we got 2465's, and I really liked the 2465. But I always felt the 2465 was more fragile than the old 465 - 475 series stuff, and the things that broke in the 2465's were always expens
ive and proprietary. If you were going to buy one for home use, it might be easier to keep the older stuff going because they're tougher and fewer of the parts are made of unobtainium.

But .. my REAL point here ... for home use for the average hobby user, we almost never really NEED a 400 MHz or even 250 MHz scope. My home scope for years was a Tek 455 with 50MHz bandwidth. I did design development work at home and fixed a zillion things with that scope and rarely found the 50 Mhz bandwidth a problem. For the less demanding hobbiest, it might NEVER be a problem. Of course you have to apply judgement and realize the limitations of the instrument, but that's ALWAYS the case with any measurement. People tend to think they have to always have the highest performance and anything less is inadequate (hence the internet surfers with 3.2GHz Pentium IV computers and a Gig of Ram to send e-mail) but if you hold off buying a scope because you can't afford the 250 MHz or 400 Mhz scope that you THINK you need ... be aware you can do 99% of your oscilloscope work with a decent 50Mhz scope. If you're designing fast logic or think you need to look at the carrier of a
VHF transmitter, you need speed, but for fixin' radios, it's rare. Because of the "gotta have the fastest" mentality, the old 455's and such are real bargains, and will serve the average hobbiest well. Any scope is better than no scope. I can't imagine life without an oscilloscope in my basement. I have four ... including a 922 (15MHz??) that's my favorite for pick it up and go to help a friend fix something ...

Just my humble opinion based on some years of experience ...

Jim
AB4CZ

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ab4cz

RE: Oscilloscopes (WAS: spectrogram)

In reply to this post by Ron D'Eau Claire-2

By the way, one more comment on Tek scopes .. I loved the 475, REALLY loved the 2465, but I can barely tolerate Tek's DSOs... Maybe I'm just to dumb to use them, but I think the menu structures in most of the Tektronix digital scopes are non-intuitive and obtuse. If you want a really neat digital scope, look for a LeCroy. When I bought DSOs for my last company, I had HP, Tektronix, Philips, and LeCroy bring scopes in for me to play with. I refused to look at any of the user manuals. If I needed the manual to get basic use out of the scope, I didn't want the scope. The LeCroy won hands down for ease of use. I'd REALLY like to get a 350MHz or so LeCroy for home use!

jim
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