Oscope ?

[Leo_Gnardo]

I made an offer on a scope ,and it was accepted. It is a Tektronix 2213. Says it works ,but may need calibration.

That looks like it will do the trick! Good going. Hope it's "very affordable."

Do they have any more?

[gtrplayr1976]

That looks like it will do the trick! Good going. Hope it's "very affordable."

Do they have any more?

Well..I don't know..I paid $92 shipped ,and I think he does have another just like it. He was asking $99 or make offer. I offered $75 ,and he took it. You may be able to get the other cheaper.

[salvarsan]

Well..I don't know..I paid $92 shipped

Good score.

Pay attention to that little "CAL" point just right of the screen. That's your 1 kHz calibration signal. With a cheap pot, it'll get you pretty far without any other signal generator.

[Leo_Gnardo]

Well..I don't know..I paid $92 shipped

Well I know... dude, you scored! I got a feeling you're paying less than a dime on a dollar what it was originally. YUSSSSS...!!

Gonna have to rattle up another probe eventually. As a spare, and for those times you need to look at 2 things.

Terrific!

[gtrplayr1976]

Well I know... dude, you scored! I got a feeling you're paying less than a dime on a dollar what it was originally. YUSSSSS...!!

Gonna have to rattle up another probe eventually. As a spare, and for those times you need to look at 2 things.

Terrific!

Whew...that makes me feel better. I need to learn to look at one thing first

[gtrplayr1976]

Good score.

Pay attention to that little "CAL" point just right of the screen. That's your 1 kHz calibration signal. With a cheap pot, it'll get you pretty far without any other signal generator.

The red cal knob ? With a cheap pot I can do what ? Forgive my newbieness here.

[gtrplayr1976]

Would an adjustable resistor like this work for a dummy load as long as it was ranged correctly ? I found a 225 watt 100ohm like this. I'm guessing it's adjustable to 100 ohm ?

[Leo_Gnardo]

Would an adjustable resistor like this work for a dummy load as long as it was ranged correctly ? I found a 225 watt 100ohm like this. I'm guessing it's adjustable to 100 ohm ?

Given that the largest resistance you're going to need should be 16 ohms, a lot of that resistor will go to waste, plus you will have to discount the wattage rating by 84% at 16 ohms down to 98% at 2 ohms. You'll also be spending time & aggravation faffing around with that adjustment slide every time you need a different ohmage. Not recommended.

Thanks for the likes, my head's expanding! Gonna need a new hat now. Where can I get an 8½?

[gtrplayr1976]

Given that the largest resistance you're going to need should be 16 ohms, a lot of that resistor will go to waste, plus you will have to discount the wattage rating by 84% at 16 ohms down to 98% at 2 ohms. You'll also be spending time & aggravation faffing around with that adjustment slide every time you need a different ohmage. Not recommended.

Thanks for the likes, my head's expanding! Gonna need a new hat now. Where can I get an 8½?

Never thought of that. Crap. So would it be better if it were lower resistance would it be any better ? Maybe a 10 ohm 225 watt ?

[JoeM]

The cal point is a square wave. It's used to adjust the probe. There's a probe compensation, and with the cal point you adjust the probe for the best square wave. (flattest top). I'd still recommend a good signal generator.

[gtrplayr1976]

The cal point is a square wave. It's used to adjust the probe. There's a probe compensation, and with the cal point you adjust the probe for the best square wave. (flattest top). I'd still recommend a good signal generator.

I just bought a generator ,so hopefully it will be good enough for this.

[Leo_Gnardo]

Never thought of that. Crap. So would it be better if it were lower resistance would it be any better ? Maybe a 25 ohm 225 watt ?

Sneakin' up on it. 16 would be ideal, 15 or 20 probably the closest value offered. Still gotta move that darn slider every time. Also, it's a hollow cylinder, right? Good idea to mount it on a long piece of metal or thread rod so you don't singe whatever it's sitting on. That's why those fancy metal-finned resistors (Dale etc.) are a hit. Bolt to a metal plate or box and off you go. Parts Express MAY have some, and of course the usual suspects Mouser DigiKey Newark Allied, like that. Nice to find 'em on surplus for cheap.

One thing to think of too, if you make up a load box and test even medium power amps, they get very hot. Besides the 1000W rack plate arrays, I also made a couple "portable" ones in Hammond aluminum boxes. One day I ran a 100W + amp then went down to the kitchen to make dinner. After awhile I smelled something cooking and it wasn't my food. It was the load box, melted its rubber feet off and was charring the carpet on the workbench. Pee-yoo! I have that blackened area to remind me every day to not do that again.

[gtrplayr1976]

Sneakin' up on it. 16 would be ideal, 15 or 20 probably the closest value offered. Still gotta move that darn slider every time. Also, it's a hollow cylinder, right? Good idea to mount it on a long piece of metal or thread rod so you don't singe whatever it's sitting on. That's why those fancy metal-finned resistors (Dale etc.) are a hit. Bolt to a metal plate or box and off you go. Parts Express MAY have some, and of course the usual suspects Mouser DigiKey Newark Allied, like that. Nice to find 'em on surplus for cheap.

One thing to think of too, if you make up a load box and test even medium power amps, they get very hot. Besides the 1000W rack plate arrays, I also made a couple "portable" ones in Hammond aluminum boxes. One day I ran a 100W + amp then went down to the kitchen to make dinner. After awhile I smelled something cooking and it wasn't my food. It was the load box, melted its rubber feet off and was charring the carpet on the workbench. Pee-yoo! I have that blackened area to remind me every day to not do that again.

I found a 10 ohm, but if you were running a 100 watt amp with 1000 watt resistors maybe I should try something else..

[Leo_Gnardo]

I found a 10 ohm, but if you were running a 100 watt amp with 1000 watt resistors maybe I should try something else..

Nope that's not it. What I have for loads are 2 rack panels with an array of 20 resistors on each, 1000W per panel & a fan behind that (fan rarely used unless really big power amps are on test). Got the resistors half a buck apiece on surplus.

ALSO a couple of "portable" loads, each one a box with resistors inside, about 3x4x6 inches. One of THOSE singed my workbench. (insert DUH smiley here = me) Without heatsinking or fan those boxes can get hot. Don't find out the hard way.
Here's a nice 50W 1% 8 ohm @ Mouser, $5.08 ea. get 4, set up series & parallel pairs for 100W 16 & 4, and series/parallel for 200W 8 ohm. Affordable, and tough BUT you will have to bolt to metal panels to properly dissipate their heat. Any castoff heatsink or chassis or panel should do. You may be able to find similar R's for sale on surplus somewhere.

71-RH0508R000FE02 Mouser part #

linky:

http://www.mouser.com/ProductDetail/...P0g27agDHvk%3d

[Steve Conner]