Build a Audio and RF Signal Tracer using a Guitar Amplifier

[@area46241]

That's a winner for sure! Going to build one right away...got a little 386 ready and waiting....

[@AllAmericanFiveRadio]

Thank you.

[@TonyButchT]

Nice circuit! Good demonstration about effectiveness of different type diodes! Thank You!

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@fullwaverecked]

Great video! Just what I needed. I put a 4" 30 watt Eminence speaker in a Eico 147A with a guitar jack in place of the rf jack. Works great!

[@AllAmericanFiveRadio]

Thanks

[@fullwaverecked]

@@AllAmericanFiveRadio I think I have all the parts to make this finally. :)

[@edtully2740]

Looks like a handy thing to have, I will make one this weekend!

[@AllAmericanFiveRadio]

A signal tracer is a great troubleshooting tool. Tracing a signal through a circuit and also locating noise in a circuit.

[@edtully2740]

Works like a charm. I was able to use a 1N4148 fast switching diode. A Schottke I had also worked well. Thank you.

[@AllAmericanFiveRadio]

@@edtully2740 The signal tracer is very useful, and thanks for the information.

[@fullwaverecked]

This is very handy and cool Rick! BTW, I've been playing an electric guitar plugged into the RF input of an Eico 147A signal tracer. Its alot of fun. (I replaced the 1.5 watt 4" speaker with a 30 watt Eminence 4", plus another 8 ohm speaker plugged into the speaker test jacks). The amplifier circuit is similar to a fender 5f1 champ, and it does not disappoint. Thanks for the video :)

[@AllAmericanFiveRadio]

Thanks

[@ZenithClarity]

I recently sold a guitar amp that i purchased at the Salvation Army a few years back. It sat around all that time until i got around to fixing it. Looked great and sounded pretty good to playing mp3 player through it. I sold it on CL and knew then i would regret it. Would have been perfect for this.

[@AllAmericanFiveRadio]

Thank you,

[@kurt-akeandersson1570]

Thanks for the good education! Can I use an Radio Shack mini amplifier/speaker (Power Output 200 mW) instead of a guitar amplifier to signal trace in my old tube radio?

[@AllAmericanFiveRadio]

Yes if it has a microphone input.

[@BIGMOTTER1]

I built this. Works like a champ. Thanks again Rick!

[@AllAmericanFiveRadio]

Thanks

[@ronrowlinson5308]

Can I use this circuit with powered pc speakers or would there not be enough amplification? I like this setup but would like to make it in a more compact package. Great page, great videos. Thanks.

[@AllAmericanFiveRadio]

If it can amplify a guitar peck up it should work.

[@user-su5sq5ib3i]

Definately going to build one. Thanks very much

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@kingtutt61]

Rick....great job! Going to work on this very shortly.

[@AllAmericanFiveRadio]

Thanks

[@garyryan3563]

Very usefull thanks. Would it work fed into powered computer speakers instead of amplifier?

[@AllAmericanFiveRadio]

Any audio amplifier that has a pre-amp. You can pick up guitar amps at flea markets for little money.

[@guruji243]

I built one with capacitor only. I am just beginner in electronics trying to fix a transistor radio. Signal arrives to a point.Does that mean near components are bad?? Thanks.

[@AllAmericanFiveRadio]

That could be true. Send me the manufacturer and model number. I'll be glad to help if I can. [e-mail]

[@theguitaramptech]

A neat little concept. I will eliminate the 0.047uf cap on my probe as I suspect it is making the shield ineffective (hence the buzz). Cool Tool. Thanks.

[@AllAmericanFiveRadio]

The 0.04uF capacitor is for isolation. Do not remove from circuit.

[@theguitaramptech]

@@AllAmericanFiveRadio thank you !

[@roncarter2188]

When you say you don't have to do anything to the guitar amplifier do you mean that you don't even have to turn it on? This may sound like a stupid question but I actually have really no idea how audio signal tracers work, but I'm learning and I really appreciate your video and layout of building one of these.

[@AllAmericanFiveRadio]

No change to the guitar amplifier.

[@seantonnesen1636]

Thanks Rick, I will be building one of these today.

[@AllAmericanFiveRadio]

Thank you.

[@kc9kel]

kew. ummm...could we add a visual indicator á la Heathkit, but LED(s) to indicate signal strength since we don't have Magic Eye tubes...?

[@AllAmericanFiveRadio]

You could add and led indicator. You would need a small amp to drive the led, one or two transistors, and a battery.

[@vihuelamig]

My theory is a bit poor on this sort of thing. The other day I came across someone who said that you can check if an oscillator in a radio is working by using another working radio positioned next to it and tuning through the band. I tried it and sure enough it worked. That got me thinking. How many diagnostic tools can be made from that one radio? I presume we can tap into the amplifier in the radio as a signal tracer? tap into it as a signal injector? perhaps others? Just a thought!

[@AllAmericanFiveRadio]

Thanks for the thoughts, I do need to do a video on signal injection. Oscillator Trouble Shooting Using Radios as Testers Demo kzbin.info/www/bejne/d6avgWZnmLF1g7M Searching My AllAmericanFiveRadio Channel kzbin.info/www/bejne/apyac6x-ps1rgNU

[@johnnytacokleinschmidt515]

AA5 did build a tracer and signal substitution test rig from a later all American five tube radio. It was an idea I had cogitated and one day I find his video. You are on track with your thinking and executing it will help you learn and expand your mastery. Good luck!

[@wsscott72]

I know this is an old topic, but I’m trying to find your video showing how you built the Tracer Probe. I can’t find it. Could you help? Thanks.

[@AllAmericanFiveRadio]

I can not find that video either. I must have deleted it because I did not think it was a good idea.

[@wsscott72]

I built your RF probe on a breadboard last night, and wondered if I could connect the output directly to my tablet oscilloscope instead of to my guitar amp, and see the RF signal there. I have a 1960s Channel Master 6519 that I can't get any AM stations on. The audio section of it is good, Ive got that working. Could I probe the RF section from the antenna to the audio section with this probe and see if any signal is being received and going through the circuit. I'm trying to figure out where the problem lies.

[@321reh]

What A Handy Dandy Little Circuit You Have There Rick!!! Thank You Once Again For A Most Outstanding Video,,,Best Regards From The:Other: Rick

[@AllAmericanFiveRadio]

Thank you.

[@damusicianstrikesback5337]

Very useful and looks easy to build!

[@AllAmericanFiveRadio]

Thank you.

[@deuceelec]

Is there a reason that you ground at the capacitor (2:49mins) and not take a chassis ground for your black lead? I'm trying to get this to work, but it appears genuine 1n34a diodes are not readily available, with Schottky diodes being sold under the guise of 1N34a.

[@AllAmericanFiveRadio]

The capacitors isolate the chassis under test and the chassis of the guitar amplifier. Ebay item number 133530100291

[@deuceelec]

@@AllAmericanFiveRadio You're very kind sir, thank you.

[@jolewk]

Thanks, Rick. Can I use this circuit with a 5 watts mini amplifier box?

[@AllAmericanFiveRadio]

If you amplifier can amplify a guitar, it will work.

[@luisantoniomarrega3713]

Parabéns amigo. Este provador é simples, mas exelente! Rio RJ Brasil

[@AllAmericanFiveRadio]

Thank you.

[@RC-Heli835]

Do you know if this would work in the line in or mic jack of a PC? Might have to have Audacity installed to use the PC speakers as a monitor?

[@AllAmericanFiveRadio]

I would not try this on any input of a PC. PC speakers with an amplifier are not sensitive enough. Go to a Flea Market and buy an guitar amp for about $25.00. Or look on eBay.

[@RC-Heli835]

@@AllAmericanFiveRadio Thanks I actually have a guitar amp, I was just wondering because I see many folks making tracers out of computer speakers that have powerful amplifiers inside them. I have a Stryker 955 10 Meter radio that had a slightly shorted speaker plugged into it for about 6 hrs before I started to smell burned electronics. I unplugged it and used my back up CB the rest of the day in the dump truck. I fixed the speaker and ran that radio another week but I had lost half of the audio volume that I once had. Near the end of last week though it got weaker and weaker throughout one particular day and I could hardly hear anyone so I plugged back in my backup radio. I want a signal tracer so I can trace back to where my audio is dropping out.

[@kwacz]

I do like this and am going to build it. I was going to use an old tube radio with a broken bakelite case but then got to wonder If i were to build this circuit with a rca plug, could i use it with either a transistor amplifier such as the tape input of a stereo receiver as well as the input of a tube radio? Or is it best to use with a tube amp only? Dont want to blow up the transistor amp should i probe something with more gain than the connected receiver can handle.

[@AllAmericanFiveRadio]

You should be able to use a transistor amplifier with a microphone input.

[@kwacz]

@@AllAmericanFiveRadio I tried this and no matter what amp i use it loads down the radio under test so much it actually mutes all audio. once i get past the first two tubes down the chain it works great but the first 2 tubes it drowns out completely. tried adding a 10 meg resistor in series with my test probe and it helps the loading on the tubes i can hear but not enough to make the ones its drowning out work.

[@AllAmericanFiveRadio]

@@kwacz You have not told me what you are using. The amplifier must be able to amplify a guitar, a microphone, or a magnetic carterage for a 33 1/3 record player. I’m not sure what you mean by dorwns out, that means loud to me.

[@kwacz]

@@AllAmericanFiveRadio I am using an amplifier with a microphone input. It has a low z and hi z switch. I tried both positions. I then noticed that the problem occurs with the amplifier not even connected to the audio probe. Completely disconnected so Im not sure what to think of that but maybe simply connecting it to the first three tubes in the circuit is either shorting out the rf or stopping the oscilator. Just a guess.

[@AllAmericanFiveRadio]

@@kwacz That’s interesting, where are you testing on the Tube? Tube number and pin number. I think I should do another video, a build and demo. Is your amplifier battery or AC?

[@edgee4]

Greetings, I am having a hard time trusting the sellers of the 1n34a germanium diodes, a lot of the reviews of the sellers say they are actually silicone and from what I gathered in your video silicone is insufficient. If it is a silicone 1n34a will it work as well as the germanium? I'm in a hurry to build this and the silicone is readily available in small quantities. However I want it to be as sensitive as possible. Thank you.

[@AllAmericanFiveRadio]

A germanium diode forward bias is about 0.3-0.4 volts. A silicone diode forward bias is about 0.6-0.7 volts. So the answer is NO. I'm working on a video idea. Let you know when I put it up.

[@edgee4]

@@AllAmericanFiveRadio Thank you I will be looking forward to it.

[@mowwow1998]

Great video and great testing device. Just wanted to know how critical the uF capacitor values are and whether I can use higher rated 1Kv/2Kv ceramic caps (which I have plenty of at hand) instead of the 630V which seem to be expensive to purchase on eBay? I assume the voltage rating of the caps should not make any difference but just wanted to make certain this is the case. Thanks.

[@AllAmericanFiveRadio]

Yes a higher working voltage is good.

[@mowwow1998]

Thanks for taking the time to reply. I always love the clear and concise way you explain things in your vids making the theory a lot easier to follow.

[@ikehorseman570]

Do the capacitors have to be rated 630 volt if I use it on a transistor radio only?

[@AllAmericanFiveRadio]

I would not use capacitors less than 630WV because the voltage deference the amplifier and the unit under test can be very high.

[@bigfrank5]

Awesome!! Now I know what to do with one of my guitar amps I can't even give away!!

[@AllAmericanFiveRadio]

Thank you.

[@kc9kel]

...add a little reverb.....😃

[@user-su5sq5ib3i]

Thanks for sharing I want to build one of these

[@AllAmericanFiveRadio]

Your welcome.

[@seankennedy8506]

Would this be useful for finding the source of a dropout or distortion of volume on the output channels of an Av Receiver/Amplifier if I fed a pure sine wave signal from a MP3 or laptop into the amplifier?

[@AllAmericanFiveRadio]

This works on analog Audio, AM and FM RF radio signals.

[@seankennedy8506]

@@AllAmericanFiveRadio Awesome thanks

[@gerrygoyette5891]

Hi Richard will this signal tracer work with an RF FM signal as well as with an RF AM signal?

[@AllAmericanFiveRadio]

Yes it will

[@gerrygoyette5891]

Thanks! I just finished you book "The AA5 radio" Great work I learned so much!

[@RC-Heli835]

Will it detect audio with the the 1N34A in place pernenantly?

[@AllAmericanFiveRadio]

Yes.

[@RC-Heli835]

@@AllAmericanFiveRadio Ok thx! I'm trying to get another probe done this evening and I have the stuff now to try your guitar probe.😀

[@yusup3199]

Can I replace the ampli with small amp like ordinay lm386 amp?

[@AllAmericanFiveRadio]

If the chip can amplify a signal from a guitar. Also if it can handle vacuum tube circuits.

[@hawkinsn31]

What does the resistor do ?

[@AllAmericanFiveRadio]

It is the audio and RF return path.

[@johnallenrichter]

Are RF and AF signals both AC current?

[@AllAmericanFiveRadio]

Yes both are AC signals

[@rogeriozambotto8539]

Hi there...can I use this circuit with computer speaker? ty

[@AllAmericanFiveRadio]

The amplifier must be able to amplify small signals.

[@georgenearchou9390]

I just built this feeding it into the phone input of an old vintage amp. I get the audio signal with the diode either switched on or out. But do no believe I am getting RF is there a possibility of loading the test circuit with this design impacting the RF signal? I have used the same components, though the diodes I have are 34s not 34As but are germanium.

[@georgenearchou9390]

PHONO

[@AllAmericanFiveRadio]

In an audio circuit you will hear audio this the switch in RF mode, but the audio will be some what muted. Make sure your diode is good.

[@AllAmericanFiveRadio]

This circuit can only load a signal by 2.2M Ohms. If something is loading down the signal it could be your amplifier.

[@georgenearchou9390]

@@AllAmericanFiveRadio Thx for your prompt reply much appreciated. Both Diodes test OK with a multimeter. When I run a direct RF only signal from my signal generator directly connected to the probe I do not get any sound, only when I switched it to modulated to i get a tone and that is both with diode switched in and out and no real change in the volume.

[@AllAmericanFiveRadio]

@@georgenearchou9390 This circuit detects Modualted RF like in a AM of FM radio.

[@BJcanal270]

Thanks for sharing your knowledge

[@AllAmericanFiveRadio]

Thanks you, and your welcome.

[@celtichongy]

Excellent as usual AA5R, keep up the great tutorials and best wishes for 2017 Rick.

[@AllAmericanFiveRadio]

Thank you.

[@TheShawna1]

Could you let me know what the 2.2M ohm Does thanks.jim

[@AllAmericanFiveRadio]

In audio mod it has no purpose. I RF mod it is the RF return path.

[@jonathanhorne6503]

How important is the 2.2m Ω value? How low and high can you opt to use?

[@mikedegrande2936]

Does it matter which type of capacitor ?

[@AllAmericanFiveRadio]

Don't use an electrolytic capacitor.

[@berniken6511]

Hi Rick, a nice little circuit. I will be building this its just what I need. Thank you.............................Berni

[@AllAmericanFiveRadio]

Thank you.

[@TechTins_Projects]

Brilliant I will be making this.

[@AllAmericanFiveRadio]

Thank you.

[@ikonix360]

would a 1N5711 work as good as the germanium diode?

[@AllAmericanFiveRadio]

I think so. Thank you.

[@ikonix360]

@@AllAmericanFiveRadio you're welcome

[@eddieng4990]

Hi, can this signal tracer work test tube amp 500-600dc voltage thanks

[@AllAmericanFiveRadio]

The capacitors I used are rated at 630WV(Working Volts). If you need a higher voltage buy higher WV capacitors. What are you going to be testing?

[@eddieng4990]

i try to test tube amp, the voltage around 500 to 600v dc, i don't know about the signal tracer and try to learn it. thanks @@AllAmericanFiveRadio

[@AllAmericanFiveRadio]

What are the audio power output tubes? 6L6's

[@eddieng4990]

yes, 6L6 p/p 40 watt class A per channel thanks@@AllAmericanFiveRadio

[@AllAmericanFiveRadio]

@@eddieng4990 According to my GE Tube manual the Max Plate Voltage for a 6L6 is 360VDC. But I have seen from other sources an plate voltage of 400VDC for Class AB operation. When your signal tracing your checking the control grid (input) and the plate (output) of the tube. So the signal tracer should be OK because the capacitors used are 630WV (Working Volts). Usually the highest voltage is in the power supply and these signal to trace there.

[@Radio478]

Fantastic thanks 😊 👍

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@ronbercan1000]

good video. very helpful.

[@AllAmericanFiveRadio]

THANKS

[@Edmorbus]

Thanks for sharing

[@AllAmericanFiveRadio]

Thank you.

[@akepatinagaraju8564]

Thanks you sir

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@ragnarw.eliansson5299]

Very smart

[@AllAmericanFiveRadio]

Thanks

[@akepatinagaraju8564]

👍👍👍👍👍

[@AllAmericanFiveRadio]

Thanks

[@rflberg]

Try a Schottky diode

[@AllAmericanFiveRadio]

Thank you.