signal generator

[bonealone]

Hi all, wondering what is good to look for when shopping for a signal generator for amp work. What is a decent price? (one that will compliment a Tex 2245A scope). Thanks!

[PRR]

> one that will compliment a Tex 2245A scope

My tone-boxes never have anything nice to say about my 'scopes.

[sluckey]

Do an eBay search for "hp function generator". I use an HP 3310B. It's a '70s model. Very versatile and goes very well with my '70s TEK 465B.

HP will compliment your TEK very well, although, if you want to match period-wise, go for one of the later models with push buttons.

...Steve

[bonealone]

PRR.........why did I know you would come up with something like that? (and to think they call ME the king of sarcasm at work)!

[PRR]

> signal generator for amp work. What is a decent price?

MSRP $81, $69 if you shop around....

http://www.cs-sales.net/bk3001.html sale for $69, may be low stock

http://www.byramlabs.com/product_info.php/products_id/7533 $69

http://www.alliedelec.com/ or http://www.mouser.com/ search for "BK 3001"

http://www.fotronic.com/b+k%20precision/3001.htm

Global Specialties has re-issued the 2001A, a fairly sweet box if someone else pays for it (~$200). Try Mouser.com and search for 105-2008

[bonealone]

Thank you sir, I shall indulge myself upon the research. (gives me something to look for anyway, and something else to spend money on)!

[tbeck]

Here's another inexpensive one. I've had one of these for at least 17-18 years, I use it regularly for testing amps.  They still make them. Easy to use, not super precise, but then this is guitar amp work, not rocket science.  If you want true precision, you'll have to spend way more money, but I think that's kinda pointless for the intended use.
http://www.mcminone.com/search.asp?keyword=72-505&btnSubmit.x=5&btnSubmit.y=4&btnSubmit=GO

[madison]

How about this?

http://www.e-dsp.com/software-functionsignal-generator/

[PRR]

> Here's another inexpensive one.

That Tenma Hand Held Audio Generator is the same guts as the B&K, with a less sexy brand, at a lower price. Good find.

> How about this?

Software Function/Signal generator, there's several free and cheap out there. All need a PC at the workbench. I don't have room even for a flaptop, I don't like having a 3 Volt $600-$2,000 laptop jacked into my 567 volt tube amp, GHz CPU garbage contaminates audio. Actually I have done PC-based testing on audio gear, and it can do some amazing stuff, but as tbeck says "not rocket science".

[PRR]

http://www.garnetamps.com/book.htm

Obviously a staged shot, but I can well believe that this gear was used by Gar "Garnet" Gillies. The signal generator is right-center. These EICOs were adequate for any gitar-amp poking. They mostly burned-up their power transformers, easily fixed.

[Direwolf]

While searching the forum for signal generators, I found this old thread. I was wondering if anyone has used one of the kits to build a simple sig gen? Velleman makes one and there are some others. Here are a couple of links. If anyone has an opinion on these, I'd like to hear it.

Thanks!

http://www.ramseyelectronics.com/cgi-bin/commerce.exe?preadd=action&key=K7000

http://www.altex.com/Velleman-Signal-Generator-Kit-MK105-P146415.aspx

[PRR]

The Velleman K7000 looks like a total bargain (and Ramsey are good people too).

Impartial review:
http://www.epanorama.net/phpBB3/viewtopic.php?f=12&t=18225

Manual:
http://www.velleman.be/downloads/0/illustrated/illustrated_assembly_manual_k7000.pdf

Tweaks:

Around hi-volt tube amps, C4 should be 600V rated, they probably give you a 100V part because that's ample for "all modern electronics". Also if you use a 4-inch speaker, there's no reason for C4 to be over 0.05uFd. If you can't fit a 0.05u 600V cap on there, make "C4" a wire jumper, and mount a 0.05u 600V cap between "IN" and your input jack.

Same 600V for C5. We might want to inject at a high-voltage point; anyway mistakes happen.

Also add 220K in series with the C4 input cap, with a switch to short it. The K7000 has a 50K input impedance, poking it at tube circuits will load-down the signal. 220K in series will reduce loading and get sensitivity in a more practical range for tube-work; the switch lets you get high sensitivity when you need it.

RV2 could probably be a 100K audio-taper for better adjustment range.

An oscillator-kill switch is probably a good idea.

You want battery power for zero-buzz.

[Direwolf]

Thanks PRR. I worked on RT-524/246s in the Marine Corps and got pretty good at diagnosing problems with a sig gen and an o-scope. Guitar amps are different to an extent but it really is all the same and since I'm building amps, why not build test equipment, too?

By the way, have you read Gar Gillies book? If so, what is your opinion of it?

[birt]

http://www.geofex.com/FX_images/q+dosc.gif

and i also use one of these: http://www.glowbug.nl/valve/GM2317.html