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Recommendation for Audio Function Generator

J

j4570

Member
So I'm trying to pick up a few pieces of test equpment.

An Audio Function Generator is on the list.

What would you look for. I've seen everything from EICO 377 (tube based and most probably will need repair) to Heath IG-18 to RCA/VIZ WA504, etc.

What would you buy if you were a hobbyist with a few tube amps and AM radios?

What's a reasonable price for those units?

I serached the archives and found you pretty much need variable frequency so that rules out the new handhelds that are under $100.

Thanks,

Jason
 
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If you only need audio frequencies, then there are many options using PC and sound card - perhaps a buffer or isolation circuit. Second alternative is to find a circuit and breadboard it or find a kit (this is DIY!) I used Leader stuff and it seemed well suited for audio. Unless you need ultra low distortion, the requirements are not that stringent. Good hunting. Steve
 
If I did not already have the stuff, the PC and soundcard would be very tempting to get. You can combine several pieces of test gear on your PC nowadays and the distortion with a sound card would be much better than your average inexpensive gear probably. Heck, that is what most test gear is nowadays. Computers with appropriate hardware and interfaces. Except it may be alot cheaper to upgrade a PC program than whatever software is in the lab gear. But I am still one foot in old school I am afraid.
 
Working on tube gear with high voltage, I am somewhat nervous about hooking up my primary laptop to any piece of history with high voltage.

JW
 
OK then, use a coupling cap that is rated higher voltage than any voltage in the unit, to block DC. And if it needs it, an isolation transformer.
 
Function generators, in general, have higher distortion figures than pure sine generators. Function generators, however, have very flat amplitude response where pure sine generators require some fancy leveling circuit.

A function generator is fine for most troubleshooting and many give you a sweep function and/or modulation capabilities. This can come in handy. Most function generators go beyond 2MHz, this allows you to use them to align AM radios.

You just shouldn't use a function generator to measure distortion. The residual distortion of the meter will probably be higher than the equipment being tested.
 
avionic said:
Keep and eye on ebay or craiglist for a LEADER LAG-27 or -17..
http://www.audiokarma.org/forums/showpost.php?p=2623784&postcount=1

There is one listed on ebay now..No ,its not mine. I'm using mine.
Click to expand...

+1 on the LAG-27. Grabbed one in a pawn-shop a couple of years ago, has served me well since. I like how it's very easy to adjust it with good precision and the display is nice and big and accurate.

Here's mine, 2nd tier from the top, to the right:

attachment.php


az
 
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The old Eico 377 is a very respectable audio generator, but it's true that some restoration effort is likely to be necessary. They're cheap now because they were wildly popular in the day. Leader's LAG-27 is essentially a solid-state version of the same classic R/C oscillator circuit design that goes back to HP's earliest audio generators. It should be completely free of heater-induced hum in the output signal, and it probably has better square-wave shape than the Eico. Consider an HP 200CD if you want the best instrument in its class. Many of these old battle wagons are still working as if they were manufactured yesterday.
 
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