I'm going to tap it tomorrow

[W3MPS]

I just finished figuring out a design for a 40 db tap attenuator. However, I can't quite seem to find a definite answer to my final dilemma in the design. If you put two 1/2 watt resistors in parallel, the cumulative power handling capability should be one watt, correct?

Ugh, It always seems like one project begets another.

I picked up an old Radio Shack CB base radio for a friend, only to realize it has been goobered with. Well, I'm almost done de-goobering it, but now I have to make sure it's on frequency. Cool, my MFJ-269 can help. Wait, now I have to attenuate the signal lest I smoke something.

Oh well, it is an excuse to make some nifty test equipment. Now if I can only find a decent used 'Scope for a good price.

[N8YX]

If you put two 1/2 watt resistors in parallel, the cumulative power handling capability should be one watt, correct?
Correct.

[N2CHX]

As long as they're the same value. The resistor with the lower value will pass more current and therefore the power it will dissipate will be greater than the higher value resistor, if they are different.

[W3MPS]

As long as they're the same value. The resistor with the lower value will pass more current...

Hmm, that's what I was afraid of. I'm mixing and matching to get the resistance values I need. I miss the old days when Radio Shack actually had a decent selection of components.
I'll put it together and see how it goes. Eh, it is a prototype anyway.

Guess I'll be ordering from Digikey for the revised design.

5W or more carbon film resistors? Heck yeah, turn all the knobs to 11!
DISCLAIMER: THE ABOVE STATEMENT IS NOT NOR DOES IS ADVOCATE GOOD AMATEUR PRACTICE AND AS SUCH SHOULD NOT BE TRIED AT HOME.

Thank you everybody for the input, I'll let you all know how it turns out later today.

[PA5COR]

Precision metal film resistors no option then?

[WØTKX]

Test them by measuring the surface temp... that will help "match" them.

[PA5COR]

Like Ouch! hmmmm, ouch! ? :rofl:

Ooops, too much info...:-D

[W3MPS]

Well, it works. Hooked up the tap and my 269, all channels were spot on and no blue smoke came out. I'd say I had at least $30 worth of fun putting it together and trying it out. The hardest part was finding the SO-239 connectors at Radio Shack. They were re doing the whole component cabinet and everything was in a huge cardboard box. As luck would have it, they were at the very bottom of the box.

Precision metal film would be the way to go. When I get around to ordering parts for the real deal, I'm going to say screw it and get the beefiest capacitors Digikey offers. Not that I would want to attenuate a kilowatt down to safe input levels for test equipment, but if I build something I'd rather over engineer it a little.

For a little screw around project, I'm quite pleased. I wouldn't want to put more that 30 or 40 watts to it, but it did what I needed it to.

[PA5COR]

Kudo's to you ;)

[Chris]

y u want 40db?

[W3MPS]

y u want 40db?

Why can't you fomulate a grammatically correct query?

[Chris]

y u give a shit how i tok u no wut i ment

[N8YX]

Why can't you fomulate a grammatically correct query?
Obvious post is obvious, and some folks might be posting from mobile devices with their $^%#%$^-small-a$$ed keyboards. Conservation of characters and all that... ;)

[W3MPS]

y u give a shit how i tok u no wut i ment

Sorry, grammar is a pet peeve of mine.

Although the more disturbing question is, why would I be giving turds away? And more importantly, what the hell kind of misconception am I operating under that I would think somebody would really like to have a nice, fresh, steaming pile from yours truly? :lol:

[HUGH]

It probably won't apply in this case but there is a maximum voltage rating for ALL resistors regardless of rated power or value. This is worth remembering for high-voltage power supplies such as the bleed resistors for example. This is why you may find chains of resistors instead of single values.

Happy St Valentine's day (I think that's the next thing).