Monday, 6 June 2016

Re: [Amateur-repairs] Speaking of test equipment substitutes

 

If you are measuring audio filters, there are a number of function generator chips available for not much $$.  I hate to mention Ramsey, but they offer several parts bags which, when completed, offer a highly usable audio function generator. 

If you are measuring at RF frequencies, that's a whole different story.  In an absolute pinch, I've used a GDO (grid dip oscillator) and an o'scope but GDOs are typically not too stable and require very loose coupling for stability.  

I've seen a number of old tube Heathkit sig generators on ebay and other sites, but they, as well, aren't too stable but better than a GDO.  Typically, they go only to 30 MHz.  You can always use a diode multiplier, but that also multiplies the frequency instability by the multiplication factor. 

Dave - WØLEV

On Mon, Jun 6, 2016 at 11:10 AM, Steve Toth stoth47@yahoo.com [Amateur-repairs] <Amateur-repairs@yahoogroups.com> wrote:
 

What's a good inexpensive, or inexpensive and functionally acceptable substitute, for a function generator?  Main interest is using it to measure Bandwidth on filters and Inductance. 
 
- Steve  W7SJT
"Always look for a positive solution then Improvise, Adapt, and Overcome"

"Sometimes it is the people who no one imagines doing anything, who do the things that no one can imagine".....

 




--
Dave - WØLEV
Just Let Darwin Work

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Re: [Amateur-repairs] substitute test equipment

 

Yes, any good modern o'scope can do the job of a voltmeter, freq counter, and a lot more. 

Yes, any PC outfitted with the proper apps can serve as an audio generator.  There are a number of freeware apps which can be downloaded and used.

I hope the Wavetek sig gen you have isn't the one with a white face and roughly 7" wide x 12" deep x 5" high?  That thing has 7, seven, nested phase locked loops and is an absolute bear to troubleshoot ! !  ! ! 

Dave - WØLEV

On Mon, Jun 6, 2016 at 8:53 AM, hitekgearhead@hotmail.com [Amateur-repairs] <Amateur-repairs@yahoogroups.com> wrote:
 

I am starting to go through the alignment on one of my radios and don't have every piece of test equipment listed in the service manual.

So, I wanted to see if I could use the following substitutions.

For the frequency counter & RF voltmeter, couldn't I just use my oscilloscope? I have access to a scope that can internally measure all kinds of parameters including frequency, Vp, Vrms, etc. Any problem with doing that?

Audio signal generator: I have both a program on my computer and an app on my phone that will generate audio tones at adjustable levels. Any problem with that instead of using a dedicated audio generator?

I still need to get my RF signal generator up and running. I have an old wavetek that is a little persnickety...

Thanks,
Albert
KI4ORI





--
Dave - WØLEV
Just Let Darwin Work

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[Amateur-repairs] Speaking of test equipment substitutes

 

What's a good inexpensive, or inexpensive and functionally acceptable substitute, for a function generator?  Main interest is using it to measure Bandwidth on filters and Inductance. 
 
- Steve  W7SJT
"Always look for a positive solution then Improvise, Adapt, and Overcome"

"Sometimes it is the people who no one imagines doing anything, who do the things that no one can imagine".....

 

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Posted by: Steve Toth <stoth47@yahoo.com>
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[Amateur-repairs] Re: substitute test equipment

 

I agree about the counter. The counter in you scope will not come close to the accuracy needed. There are very many counters sold out there that have poor accuracy. For accurate SSB communications you need an accurate counter. I bought two from ebay and installed 10 mhz oven controlled oscillators sold in China. I set them with WWV using the DC output from the detector on my receiver. I got it close enough that my scope showed an error of 1 hz at 10 mhz during 1 minute. This is very high accuracy. I check my counters against each other regularly by measuring their time base outputs. They are still dead on after a 20 minute warm up. A piece of test equipment that you cannot trust is worse than worthless.


Michael

Also, what transceiver are you attempting to align? Some have the wrong procedure in the service manual. I discovered this with an Icom 740. I posted a correction on the 740 newsgroup.

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Re: [Amateur-repairs] substitute test equipment

 

Oh yes you can substitute a computer generated, sound card, signal for the audio generator.

Bob


On Monday, June 6, 2016 9:50 AM, Bob Albert <bob91343@yahoo.com> wrote:


You can't substitute an oscilloscope for a counter.  The difference in accuracy is immense.  If you have another way of measuring frequency, look into that.  Sometimes a counter is overkill, so it pays to understand what you are trying to do and what compromises you can make.

Bob


On Monday, June 6, 2016 7:53 AM, "hitekgearhead@hotmail.com [Amateur-repairs]" <Amateur-repairs@yahoogroups.com> wrote:


 
I am starting to go through the alignment on one of my radios and don't have every piece of test equipment listed in the service manual.

So, I wanted to see if I could use the following substitutions.

For the frequency counter & RF voltmeter, couldn't I just use my oscilloscope? I have access to a scope that can internally measure all kinds of parameters including frequency, Vp, Vrms, etc. Any problem with doing that?

Audio signal generator: I have both a program on my computer and an app on my phone that will generate audio tones at adjustable levels. Any problem with that instead of using a dedicated audio generator?

I still need to get my RF signal generator up and running. I have an old wavetek that is a little persnickety...

Thanks,
Albert
KI4ORI





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Posted by: Bob Albert <bob91343@yahoo.com>
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Re: [Amateur-repairs] substitute test equipment

 

You can't substitute an oscilloscope for a counter.  The difference in accuracy is immense.  If you have another way of measuring frequency, look into that.  Sometimes a counter is overkill, so it pays to understand what you are trying to do and what compromises you can make.

Bob


On Monday, June 6, 2016 7:53 AM, "hitekgearhead@hotmail.com [Amateur-repairs]" <Amateur-repairs@yahoogroups.com> wrote:


 
I am starting to go through the alignment on one of my radios and don't have every piece of test equipment listed in the service manual.

So, I wanted to see if I could use the following substitutions.

For the frequency counter & RF voltmeter, couldn't I just use my oscilloscope? I have access to a scope that can internally measure all kinds of parameters including frequency, Vp, Vrms, etc. Any problem with doing that?

Audio signal generator: I have both a program on my computer and an app on my phone that will generate audio tones at adjustable levels. Any problem with that instead of using a dedicated audio generator?

I still need to get my RF signal generator up and running. I have an old wavetek that is a little persnickety...

Thanks,
Albert
KI4ORI



__._,_.___
Posted by: Bob Albert <bob91343@yahoo.com>
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Posted by at No comments:

[Amateur-repairs] substitute test equipment

 

I am starting to go through the alignment on one of my radios and don't have every piece of test equipment listed in the service manual.

So, I wanted to see if I could use the following substitutions.

For the frequency counter & RF voltmeter, couldn't I just use my oscilloscope? I have access to a scope that can internally measure all kinds of parameters including frequency, Vp, Vrms, etc. Any problem with doing that?

Audio signal generator: I have both a program on my computer and an app on my phone that will generate audio tones at adjustable levels. Any problem with that instead of using a dedicated audio generator?

I still need to get my RF signal generator up and running. I have an old wavetek that is a little persnickety...

Thanks,
Albert
KI4ORI


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Posted by: hitekgearhead@hotmail.com
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