Fun Project.

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Re: Fun Project.

Post by terrydec on Tue Jan 17, 2017 7:04 pm

I'm going to try and use a small IF can to build my probe. I'm taking photos. Tomorrow another trip to Radio Shack. I found a circuit that uses a diode, 47M resistor and .01mfd disk cap. I used my other tracer without a probe, just the RF jack.
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Re: Fun Project.

Post by terrydec on Thu Jan 19, 2017 3:33 pm

I got my amp kit today. The instructions are in a foreign language and it is missing parts. Not good! The only guide is a photo from on top. There is no way to tell the values. Oh well, there is a schematic.

I picked up a piece of double sided circuit board for my probe. I have some reservations about this. I should have spent the $35 for the one on eBay.
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Re: Fun Project.

Post by terrydec on Thu Jan 19, 2017 3:42 pm

Update. There is a Heathkit signal tracer on eBay. It is in lousy shape but has a probe. I might buy it just to get the probe
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Re: Fun Project.

Post by terrydec on Thu Jan 19, 2017 5:02 pm

I built it, turned it on and it played for about 3 seconds and it popped off. Frustrating!
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Re: Fun Project.

Post by terrydec on Thu Jan 19, 2017 6:11 pm

Boy, I really don't know about this.  Maybe some HAM can tell if I'm on the right track.  Here goes:
I bought a double sided copper clad board from Radio Shack.  I scored one side of it to separate it into two sections.  The input is a long screw.  It goes to a .01/600v disk cap.  The output is a 65 meg resistor.  It is a little high,(recommended 47 meg). a diode goes from this junction through a tiny hole, to the other side, which is ground. Here is a photo  

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Re: Fun Project.

Post by Bill Cahill on Thu Jan 19, 2017 8:31 pm

Disc capacitor and, long length combined may cause hum.

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Re: Fun Project.

Post by Bill Cahill on Thu Jan 19, 2017 8:37 pm

What voltage capacitor did you use?

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Re: Fun Project.

Post by terrydec on Thu Jan 19, 2017 11:10 pm

Bill Cahill wrote:What voltage capacitor did you use?

600
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Re: Fun Project.

Post by terrydec on Thu Jan 19, 2017 11:19 pm

Oops- hit send too soon. I claim dementia.
I have smaller disk caps but they are low voltage. I tried to keep the leads as short as possible. Remember this is going in that IF can.

(Am I really doing anything or just whistling in the dark?)
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Re: Fun Project.

Post by terrydec on Thu Jan 19, 2017 11:42 pm

Should I just buy this?

http://www.qrpkits.com/rfprobe.html
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Re: Fun Project.

Post by John Bartley on Fri Jan 20, 2017 10:35 am

terrydec wrote:Boy, I really don't know about this.  Maybe some HAM can tell if I'm on the right track.  Here goes:
I bought a double sided copper clad board from Radio Shack.  I scored one side of it to separate it into two sections.  The input is a long screw.  It goes to a .01/600v disk cap.  The output is a 65 meg resistor.  It is a little high,(recommended 47 meg). a diode goes from this junction through a tiny hole, to the other side, which is ground. Here is a photo  


Hi Terry,

I may have missed it, but I don't remember if you told us what schematic you are using to build this? Any chance of a link to the schematic so that I can educate myself?

cheers

John

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Re: Fun Project.

Post by terrydec on Fri Jan 20, 2017 12:56 pm

The upper left hand corner- Basic probe

https://www.google.ca/search?q=%22RF+probe%22&num=100&newwindow=1&safe=off&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjbrNDGkr3RAhUL3IMKHZ-pB2UQ_AUICCgB&biw=1467&bih=760
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Re: Fun Project.

Post by John Bartley on Fri Jan 20, 2017 1:20 pm

Thanks Terry. I'll keep following along.

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Re: Fun Project.

Post by terrydec on Fri Jan 20, 2017 3:19 pm

Darn! I'm about to give up. My poor attempt will never work. The kit I was looking at is only for DVM. There is a beat up old Heathkit signal tracer on eBay. I should just get that. One of the main reasons I bought this was to repair my GE console.

Oh well, back to writing
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Re: Fun Project.

Post by terrydec on Sun Jan 22, 2017 6:25 pm

This is not going well at all. There was a Heathkit signal tracer, in bad shape and for parts only on eBay. When I went in it was $50. I put in $85. I was out bid at the last second, probably by a Snipe program. I really hate that program and I've even used it. Why bid when you are locked out in the last few seconds? It kind of defeats the whole auction concept.

So far I have spent well over $200 to get my GE Console fixed. It still doesn't work, and the prospects are poor. Dumb!
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Re: Fun Project.

Post by Bill Cahill on Sun Jan 22, 2017 11:40 pm

terrydec wrote:Should I just buy this?

http://www.qrpkits.com/rfprobe.html

You should definitely buy that one.

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Re: Fun Project.

Post by terrydec on Mon Jan 23, 2017 12:55 am

Ah- An update on that. I contacted the seller and it is only for Digital voltmeters. Totally unsuited for RF. The diode goes the wrong way. At least that's how they described it.
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Re: Fun Project.

Post by terrydec on Mon Jan 23, 2017 12:57 am

Here's how obsessed I am. I almost paid $80 for a probe. I must be sick. Probably too much ink in my blood.
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Re: Fun Project.

Post by willy3486 on Mon Jan 23, 2017 8:33 am

That Tenna tracer came from MCM electronics. I have one just like it at work. Good little unit. I built a tracer back in the early 80s out of an old transistor radio that had a bad case. I found the info on how to build it from one of the 80s electronic magazines. I put it in a old car CB case I gutted for it. I used the CB speaker and built a 9 volt supply. The thing still works like a champ. A tracer and generator are my 2 most used test pieces on radios.

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Re: Fun Project.

Post by terrydec on Tue Jan 24, 2017 6:21 pm

It just gets weirder and weirder. There is now a Tenma exactly like mine, only with the elusive probe, on eBay. If it wasn't in auction I might try and get it and sell mine.
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Re: Fun Project.

Post by willy3486 on Tue Jan 24, 2017 9:39 pm

If you want to build a tracer and have a somewhat working am radio here you go. I made one around 82 and I still use it.It works really great.

tracer page 1

And

Page 2

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Re: Fun Project.

Post by terrydec on Tue Jan 24, 2017 9:47 pm

willy3486 wrote:If you want to build a tracer and have a somewhat working am radio here you go. I made one around 82 and I still use it.It works really great.

tracer page 1

And

Page 2

Now THAT is really cool.
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Re: Fun Project.

Post by terrydec on Tue Jan 24, 2017 10:00 pm

Okay. Crunch time. Let's see how many are still paying attention, or even care. I finally have a decent signal tracer, with RF input and everything. I just don't have a demodulator probe. Now- The instruction manual refers to two different test leads and the Tenma on eBay shows a probe. So it does need a probe for RF. The manual also gives instructions for aligning AM and FM circuits, even in tube radios, so it can, theoretically do this.

It turns out that I have been making a DC probe for a DVM. This is a cap and resistor in series with a diode from the junction to ground. The circuit I need has, I believe, a diode in series with a cap and a resistor to ground.

Does that make any sense?
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Re: Fun Project.

Post by Bill Cahill on Tue Jan 24, 2017 10:55 pm

Yes, and, no. Why don't you just buy the one on ebay?

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Re: Fun Project.

Post by terrydec on Tue Jan 24, 2017 11:05 pm

Bill Cahill wrote:Yes, and, no. Why don't you just buy the one on ebay?

It's an auction. I haven't won an auction in ages.
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Re: Fun Project.

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