Signal Generator: Which one to buy ? What to look for in a signal generator ?

[HP8903B]

Thanks for the great tip Mooly.

I plan to get the a function generator.
Perhaps the HP 209A

 

[veteran]

209A parameters are almost the same as the GAG-810

 

[HP8903B]

What would be a fair price for a good condition HP 209A ?

 

[HollowState]

What would be a fair price for a good condition HP 209A ?

I would say between $150 & $200. I sell them to dealers at that level.

 

[HP8903B]

That is about the price of a brand new GAG-810.

In terms of performance, how do the two compare ?

 

[HP8903B]

I like the fact that the GAG-810 has attenuation.
Most amplifiers do not have attenuation.

On the other hand, the HP 209A can sweep the audio range in 3 steps.
The GAG-810 takes 4

 

[HP8903B]

Hollowstate,

Do you have a HP 209A for sale ?

 

[HollowState]

The Hewlett-Packard is a commercial instrument made in America. GAG is South East Asia. The 209A has a low distortion mode switch on the rear panel for low frequency sine waves (audio) that's down near .05% measured, and will provide sine and square waves concurrently at the standard 600 ohm impedance. Flatness is ±0.5% over the audio range.

 

[HollowState]

Hollowstate,

Do you have a HP 209A for sale ?

Not at the moment.

 

[HP8903B]

Thanks for the info.

I will be patience and wait for a HP 209A.

Does anyone have any other suggestions ?

 

[HP8903B]

Just to make sure I understand right.

The computer option has very low distortion, much lower than the function generator.
Is this true only in sine wave ?

The function generator generates square waves much better than the computer option.

 

[HP8903B]

Hollowstage,

Could you tell me more about the Leader models that you mentioned.
Seems like the Leader LAG-120B is comparable to the HP 209A.

 

[veteran]

Just to make sure I understand right.

The computer option has very low distortion, much lower than the function generator.
Is this true only in sine wave ?

The function generator generates square waves much better than the computer option.

You're right. This is the 5kHz square wave generated by my sound card

 

[HP8903B]

haha, that's not square at all.

 

[HP8903B]

What do you guys think of this Leader LAG-120B on ebay:
LEADER LAG-120B AUDIO GENERATOR | eBay

What are some potential problems with this unit and how likely ?

 

[theoldtrout]

I've been using a Radford LDO4 [and others] for years. Low distortion, good square wave and an oscillator stop facility.

 

[nigelwright7557]

I picked one up cheap on ebay.
Has worked well for 5 years now.

 

[Salas]

haha, that's not square at all.

Ringing (not that much as in #33) is inherent in digital synthesis. The DDS instrumentation ones do filter the ringing but they lack in rise time as you push them higher to their limit VS analogue ones due to LPF. Talking under 500$. Full rise time is still available on their TTL output which is not filtered and you will be able to see the inherent ringing. Very good stability in PPM over the years and great functionality is the other side of the coin. Very good signal quality is offered by TTI-Thandar made in UK in medium to low prices (relatively, as generators go), they do good analogue still.
If using soundcard FFT for THD which is great for that, there are many cheap enough good solutions for nicely shaped square waves up to 1MHz from instruments that go to 3 or 5MHz. Their THD won't be better than -50dB though.

 

[HP8903B]

I picked one up cheap on ebay.
Has worked well for 5 years now.

You mean the Leader LAG-120B ?

 

[HollowState]

Hollowstage,

Could you tell me more about the Leader models that you mentioned.
Seems like the Leader LAG-120B is comparable to the HP 209A.

Leader is OK, Made in Japan, but is probably the best if the Asian imports. I've never owned one, but I have had some of their other stuff.