Update :73 Silverface Twin

[Leo_Gnardo]

I tried my generator out. Hooked it to my dmm ,and got it to put out 50mv pretty steady. However if I went too much above that it was very erratic. Maybe caps ,or tubes aging in the unit ?

Your generator has a level (volume) control? Gets dirty & discontinuous with age & corrosion just like in an amp. Give the pot a squirt of pot cleaner (Caig F-5) & see if that doesn't straighten it out.

Also possible that a leaky cap is adding DC to the AC signal in any old equipment. Easy enough to replace with a fresh one.

[gtrplayr1976]

Your generator has a level (volume) control? Gets dirty & discontinuous with age & corrosion just like in an amp. Give the pot a squirt of pot cleaner (Caig F-5) & see if that doesn't straighten it out.

Also possible that a leaky cap is adding DC to the AC signal in any old equipment. Easy enough to replace with a fresh one.

Thanks Leo_Gnardo. It has an output control. It's a Heathkit AG-9A.

[g1]

I tried my generator out. Hooked it to my dmm ,and got it to put out 50mv pretty steady. However if I went too much above that it was very erratic.

DMM? What about your new scope?
It will show you whether you have a nice sine wave and just the level is changing or whether the sinewave itself is changing waveform.
Jump right in, the water's fine, no risk of damaging anything.

[gtrplayr1976]

DMM? What about your new scope?
It will show you whether you have a nice sine wave and just the level is changing or whether the sinewave itself is changing waveform.
Jump right in, the water's fine, no risk of damaging anything.

Yeah I was just trying to see if I could get 50mv out of it on a display I can understand. Now I can try with the scope .

[gtrplayr1976]

DMM? What about your new scope?
It will show you whether you have a nice sine wave and just the level is changing or whether the sinewave itself is changing waveform.
Jump right in, the water's fine, no risk of damaging anything.

This is what I got last night. I guess it works to an extent. I have the generator on a 0-1 volt scale. 10x multiplier ,Not sure where to set the frequency ,but I think I had it set at one on the center knob. The other was at 0. Reading 80mv on the scope ? Set on 20M with a 10x probe.

[Tom Phillips]

Good photos. They really help support the discussion.

…Not sure where to set the frequency ,but I think I had it set at one on the center knob. The other was at 0…

It appears that the Sig Gen frequency is set to 100 Hz.

Reading 80mv on the scope ? Set on 20M with a 10x probe.

Yes. But to be precise you are reading 80 mVpp. Which is 80 mV peak to peak. To convert to V rms, which is the scale used by your DMM you would divide by 2.828 which gives you ~28 mV. You can connect your DMM to the sig gen output at the same time the scope is connected and verify these numbers.

Experiment with the settings on the sig gen and scope to learn the effect of each control.

[gtrplayr1976]

Good photos. They really help support the discussion.


It appears that the Sig Gen frequency is set to 100 Hz.



Yes. But to be precise you are reading 80 mVpp. Which is 80 mV peak to peak. To convert to V rms, which is the scale used by your DMM you would divide by 2.828 which gives you ~28 mV. You can connect your DMM to the sig gen output at the same time the scope is connected and verify these numbers.

Experiment with the settings on the sig gen and scope to learn the effect of each control.

Oh I did last night. I had all kinds of squiggly lines on there What SHOULD the frequency be set too ,or does it matter when troubleshooting an amp ?

[Tom Phillips]

...What SHOULD the frequency be set too ,or does it matter when troubleshooting an amp ?

There is no "should" but for general testing work I use 400 Hz or 1,000 Hz.

[gtrplayr1976]

There is no "should" but for general testing work I use 400 Hz or 1,000 Hz.

So, if I set the multiplier at 10x ,and the first "cycles" knob at 40 ,or 100 ,that would be 400 ,and 1000 ? I'm not sure what the other "cycles" knob does unless it's used for very low frequency numbers 1-10 cycles ,but I think I had this one set at 1 ,and the other at 0 when I did this which would be 10Hz ?

[Jazz P Bass]

You can connect your DMM to the sig gen output at the same time the scope is connected and verify these numbers.

And you will want to set your meter to read Volts ac when you measure the signal generator output.
I generally set mine to output 100mv's for a guitar amp input.
Now a microphone input will need a lot less.
Something like 25-40 mv's.

[Jazz P Bass]

Have you downloaded the manual?
http://www.google.com/url?sa=t&rct=j...52164340,d.dmg
Here is the pertinent pages for operation of the unit.

[gtrplayr1976]

And you will want to set your meter to read Volts ac when you measure the signal generator output.
I generally set mine to output 100mv's for a guitar amp input.
Now a microphone input will need a lot less.
Something like 25-40 mv's.

Thanks Jazz. I had an issue going much past 50mv on this unit. It got erratic. It held 50mv pretty steady. I may try again to see how far I CAN go.

Have you downloaded the manual?

I do have the manual. I tried to set it as they suggest ,and I could get the DMM to read 50mv ,but the analog meter wasn't reading like they say.

[52 Bill]

So, if I set the multiplier at 10x ,and the first "cycles" knob at 40 ,or 100 ,that would be 400 ,and 1000 ? I'm not sure what the other "cycles" knob does unless it's used for very low frequency numbers 1-10 cycles ,but I think I had this one set at 1 ,and the other at 0 when I did this which would be 10Hz ?

The two lower knobs set the frequency and the upper left knob is the multiplier. It's kind of like resistor color codes.

Let's say you want to set the frequency to 450hz. Set the middle knob to the first significant number of your desired frequency, that would be 40. Now set the right hand knob for the second significant number which is 5. Finally set the multiplier knob to X10 and you get 450.

If the multiplier was set to X1 it would be 45, X100 it would be 4500.

[Tom Phillips]

...I had an issue going much past 50mv on this unit. It got erratic. It held 50mv pretty steady...

Have you cleaned the pots & switch contacts yet as discussed earlier? Test equipment needs maintenance service too.

[gtrplayr1976]

The two lower knobs set the frequency and the upper left knob is the multiplier. It's kind of like resistor color codes.

Let's say you want to set the frequency to 450hz. Set the middle knob to the first significant number of your desired frequency, that would be 40. Now set the right hand knob for the second significant number which is 5. Finally set the multiplier knob to X10 and you get 450.

If the multiplier was set to X1 it would be 45, X100 it would be 4500.

Makes sense Bill ,but does this put out a selected frequency along with selected voltage ? Say I want a 1KHz frequency with 100mv output ?