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Author Topic: OScilloscope for alligning vintage radios  (Read 27539 times)
VE2ITZ
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Posts: 111




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« on: September 22, 2010, 11:29:14 AM »

Hello all:

I have just found an ad for an OSCILLOSCOPE EICO MODEL 460 which is going for 40 dollars and was wondering if any of you could give me your opinions on aligning vintage radios.

This would be my first time buying an oscilloscope and since this one is not very expensive, it would be a good thing to have for my standing projects.

Should i get this oscilloscope for radio alligning purposes of vintage gear? is it really worth it ?


I really dont want to spend a lot of money. just want something that would allow me to align say: a Realistic DX-160 to optimum reception.

I have seen that this older test equipment needs to be recapped and re-sistorized before really being functionable.

Please give me your thoughts on the matter.


Cheers and 73!

VE2ITZ
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KE4JOY
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« Reply #1 on: September 22, 2010, 12:22:06 PM »

An O scope is an indespenable trouble shooting tool.

Even if they cant sweep at RF frequencys you can still see the size of 'envelops' and is quite usefull for 'peaking' or trracing circuits.

The big question is ... does it work?

Now learning to use one is a course in and of itself.

I have a 100mhz 4 channel dual trace "Leader" its a wonderfull tool. If only I knew how to use it to its full potential.

Oh yea forgot to add. Check and see if it comes with test leads as replacements are not cheap.
« Last Edit: September 22, 2010, 02:38:15 PM by Tom Whitworth » Logged
AC5UP
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« Reply #2 on: September 22, 2010, 03:53:12 PM »

The EICO 460 is a simple recurrent sweep oscilloscope with a bandwidth of maybe 10 megs. Approximate age is pushing 50 and if it hasn't been refurbed it will need it. The scope uses unshielded test leads which is not the hot tip for precision / low noise measurements, but that's OK for this 'scope. It's good for signal tracing, not absolute measurements. Like the Heathkits of the same vintage they had specs similar to: "vertical amplifier response +/- 3dB from DC to 10 MHz". Translation: A 10 volt peak-to-peak sine wave could show anywhere from 5 to 20 volts on the CRT and be within spec.

If it's worth $40 to have something that looks like an oscilloscope on your test bench, buy it... But do realize for $150-ish you can HamFest or eBay a real 'scope from Tektronix or HP that will run rings around the EICO at half the age, solid state, and with a 'fer real 60 MHz bandwidth. Hell, you can still score the old Tek 500 series scopes for $40 or less if you're into large turquoise shack heaters.

BTW: Want to align radios? VTVM or DMM with an RF demodulator probe. The only time you'd almost need a 'scope is if you're stagger tuning an IF strip on an AM radio, tweaking out a ratio detector on an early AM-FM model, or sweeping through the IF on a vintage TV. Otherwise, a stable signal generator, good VTVM / DMM, RF probe, assortment of diddle sticks and a steady hand will take you where you want to go.
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KK5J
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« Reply #3 on: September 22, 2010, 04:01:05 PM »

A couple of points I would like to make:

1.  That scope is close to 50+ years old and maybe was good in its time but it has only a 100 khz bandwidth. Thats not sufficient for aligning amateur radios.  Perhaps audio amps and old stereos but not IF of new or "vintage" rigs.
2. Scopes are good for a variety of test functions useful to hams.  Try coughing up the bucks for a 100 Mhz Tektronix dual channel scope that works.  It will be well worth it.  As a rule, only about half of the scopes bandwidth is useable ie 100 mhz is good to around 50 mhz and so on. Dual channel is always worth it.  These can be had routinely on e-bay for $100 and they are more modern.  Transformers, caps, etc can or will certainly fail in the older 1950s era scopes-and the newer ones too.  BUT, you want to repair/align rigs, not spend your time repairing the test equipment.
3. Most scope work in the RF region will probably require a probe.  Tektronix probes are plentiful, although expect to cough up some more cash.
4. Try to Google the Tektronix literature on scopes and probes. The info is very useful and you should read it before making a scope purchase.
5.  The DX-160 was built during a period of time that 10 Mhz and 455 Khz IF were common.  You should look to the service manual or user manual for guidance before attempting an alignment so you use the right tool for the right job.
6. A good RF VTVM or DMM is also very useful for alignment work. You may even be able to use it instead of the scope for some work. Scope is more versatile.  Would also recommend a good 100 Mhz counter, and an AF/RF signal generator. Build your tool chest slowly, you will eventually have everything you need and working on rigs will be much more satisfying. Just a suggestion FWIW

   
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AC5UP
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« Reply #4 on: September 22, 2010, 04:15:01 PM »

Follow Up:

Here's the book for the EICO 460: http://bama.edebris.com/manuals/eico/460/

The book says DC to 4.5 megs @ - 3dB on the vertical amp. Which means a 10 volt P-P signal could read 5 volts on the CRT and be within spec. The IF on a typical FM receiver is 10.7 MHz which means the EICO is good enough for looking at the local oscillator and IF on an AM broadcast radio but not much beyond that.
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VE2ITZ
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Posts: 111




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« Reply #5 on: September 22, 2010, 07:12:28 PM »

Ok so here is the deal:

Forget the Eico oscilloscope.

Another fellow on some local classified had a Tektronix model 921. It looks in good shape and he had it for the same price as the EICO.

I read somewhere in the internet that Textronik is was the "cadillacs" of Oscilloscope.

Anyways, i finally got it.

The fellow who had it for sale ended up being another Ham operator. Pretty nice guy. I just brought the scope home.

I got the manual but now i need some sort of leads to connect things to.

The reason i am buying a simple scope right now is just to get a feel of how these things work. I am not planning on working on my ham shack equipment. I just want to work on some older AM and shortwave radios that i sometimes buy in garage sales. Get the hand of doing some technical electronics work without paying too much.

The scope looks in pretty good shape for its age.


Now if you guys give me an idea of what type of connectors i need to buy for this beast it would be really helpful.

the manual is on the following link:

http://www.logwell.com/tech/oscilloscopes/t921_922_sm.pdf



I appreciate all the time and help!

Thanks a bunch and 73 de VE2ITZ!

 Smiley

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AC5UP
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« Reply #6 on: September 22, 2010, 08:57:31 PM »

The Tek 921 is a much better deal than the EICO... At least it has triggered sweep.

The next thing you'll need is an oscilloscope probe. http://en.wikipedia.org/wiki/Test_probe

A proper scope probe is compensated for frequency and is more than just a really nice piece of coax with a pointy tip on the end. Do a web search on 'oscilloscope probe' and you will come across many vendors selling them. Like a 'scope, they have a frequency range and the cheapest probes will likely be good to 25 MHz which is more than adequate for the Tek 921. You'll also find 1x and 10x probes. The 10x probe has a 10 dB attenuator built in which allows for absolute minimal loading of the circuit being tested but also calls for good sensitivity in the 'scope vertical amplifier. A 1x probe offers 10 times the signal but can also de-tune a circuit as the probe coax looks like a capacitive load across the test point.

So.... What to do? Buy a probe with a 1x / 10x switch and make sure it has a variety of adapter tips that can pop on and off. One of the tips should be a tiny little needle point for small spaces while another should be an insulated J-Hook.

BTW: Tek 'scopes generally exceed their ratings so expect the 921 to be usable out to (maybe) 20 MHz or better. Voltage accuracy is best @ 10 MHz or less, but the trigger should hold solid up to 15 MHz and slightly beyond. In any case, the book is your friend...

GL
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KE4JOY
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« Reply #7 on: September 23, 2010, 06:28:27 AM »

Yes you do need purpose built test leads. Without them the scope is gimped due to noise input.
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KD0FAT
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« Reply #8 on: September 23, 2010, 07:22:53 AM »

I have had good luck purchasing 'scope probes on ebay. If you do a search, you will find multiple suppliers with new asian-manufactured probes rated at 100 mhz, with 1x-10x switches, tip clips and ground clips, and capacitance adjustment. I think that I paid about $10 each in a two-pack. The probes work perfectly on my Hewlett-Packard 1740a 'scope--a 100 mhz dual trace unit. BTW, the HP 'scope was also an ebay purchase that turned out good. It's an older lab-quality unit that works very well for me.   73, Al

Yes, you will find a 'scope very helpful with the old AM receivers. I used mine to diagnose a HQ-129x with a weak IF line. Using a signal generator and the 'scope, I was able to signal trace and find the weak stages. The old Hammarlund had a bad silver mica cap in one of the IF cans, and the resulting loss of signal strength and quality was obvious when displayed on the 'scope. Alignment was easy as well, just watch for the peak in sine wave amplitude on the screen.
« Last Edit: September 23, 2010, 07:33:53 AM by Allan Aho » Logged
K2OWK
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« Reply #9 on: September 23, 2010, 11:04:20 AM »

Hello, Just a quick note. Tektronix scope probes are available on EBay for a very low price. These are new probes, made in China. They can be used on 1X or 10X with the movement of a switch, and come with the 10X capacitance calibration tool. I have two of these and they work as good as the originals, that I also have. Just to let you know most if not all Tektronix scopes use BNC connectors for most input and output functions.

Barry
K2OWK
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KC8OYE
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« Reply #10 on: September 23, 2010, 11:30:22 AM »

not to hijack a thread or anything..  Grin

When my father passed on I was fortunate enough to inherit his Hitachi V-1050 100mhz o-scope.. i was just curious what your opinions of such a unit where.. and how it compares with things like the tektroniks?

this is an e-bay link to the same kind of unit (mine is not for sale)
http://cgi.ebay.com/Hitachi-Oscilloscope-V-1050F-100MHz-/160387308245?pt=BI_Oscilloscopes&hash=item2557d41ad5#ht_1466wt_909
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VE2ITZ
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Posts: 111




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« Reply #11 on: September 23, 2010, 11:46:21 AM »

Good stuff!


Thanks you all for all the info. I will look into ebay or go to a local electronics store here in montreal who might have some probes.

I cant wait to show my girlfriend a signal wave on the oscilloscope. She really likes to learn about my hobby. I am very blessed to have a wonderful and understanding girlfriend who lets me put up antennas in our apartment dining room. LOL!

Cheers all and 73 de VE2ITZ!



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N8CMQ
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« Reply #12 on: September 23, 2010, 01:31:23 PM »

Good stuff!


Thanks you all for all the info. I will look into ebay or go to a local electronics store here in montreal who might have some probes.

I cant wait to show my girlfriend a signal wave on the oscilloscope. She really likes to learn about my hobby. I am very blessed to have a wonderful and understanding girlfriend who lets me put up antennas in our apartment dining room. LOL!

Cheers all and 73 de VE2ITZ!

Sounds like you have a good catch there! And the scope sounds good too! Wink
If you have an audio oscillator, you can use it for training on the scope. There are many basic scope books, get one or two and read and experiment!
I have used many different scopes over the years, and an AC/DC 50Mhz scope will get you by, and as you learn to use the scope, you may want more so you can keep them hooked up for specific operations! Have fun!




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N8CMQ   Jeff Retired...
VE2ITZ
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Posts: 111




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« Reply #13 on: September 23, 2010, 02:29:52 PM »

Good stuff!


Thanks you all for all the info. I will look into ebay or go to a local electronics store here in montreal who might have some probes.

I cant wait to show my girlfriend a signal wave on the oscilloscope. She really likes to learn about my hobby. I am very blessed to have a wonderful and understanding girlfriend who lets me put up antennas in our apartment dining room. LOL!

Cheers all and 73 de VE2ITZ!

Sounds like you have a good catch there! And the scope sounds good too! Wink
If you have an audio oscillator, you can use it for training on the scope. There are many basic scope books, get one or two and read and experiment!
I have used many different scopes over the years, and an AC/DC 50Mhz scope will get you by, and as you learn to use the scope, you may want more so you can keep them hooked up for specific operations! Have fun!





Thank you!

I have just ordered a probe from Toronto.


I will definetely experiment. I will have a Saturday night date with my girlfriend doing some "probing around" LOL! Cheesy


Cheers!


Juan
VE2ITZ


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KE4DRN
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« Reply #14 on: September 23, 2010, 05:17:15 PM »

hi Juan,

here is a yahoo group for the Tek scopes

http://tech.groups.yahoo.com/group/TekScopes/

enjoy your scope, I've got a Tek 547

73 james
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