Mini-Rant: Try A Dummy Load!

[WN9HJW]

Deleted

[KC2UGV]

After my last radio problem (20 meter power folding back) I have to agree. My first leaning towards figuring out the solution was transmitting into a dummy load (And getting full power).

It's one of those "elimination of variables" things. Troubleshooting a problem relies on eliminating variables, and a dummy load allows one to eliminate the coax and antenna (Or just the antenna).

[PA5COR]

I have 4 dummy loads, the most used is one up to 3 GHz and 300 watts.
Superfluous remark, but with the current level of new Ham's it might not be so superfluous anymore... ;)

[kb2vxa]

"Or at least think first."

Brain and brain! What is BRAIN???

[KG4CGC]

Last hamfest I attended, I must have jusy missed them all. Every table that looked interesting, I inquired about a dummy load and the answer from everyone was, "You just missed it. I just sold it." Somewhere that day, a lone ham was totin' home all the DLs. Either that or there was an inside joke going on that I was clueless to.
Ebay is my next area to look but they must show up in waves. Either they're there or they're not but either way I'm getting outbid on the ones I suspect are functioning. The ones I've shy'd away from don't get much attention. Mainly, if it's too good to be true then it must be.
I remember articles as a child about building DLs. I got a couple of old paint cans. What else do I need?

[KC2UGV]

Last hamfest I attended, I must have jusy missed them all. Every table that looked interesting, I inquired about a dummy load and the answer from everyone was, "You just missed it. I just sold it." Somewhere that day, a lone ham was totin' home all the DLs. Either that or there was an inside joke going on that I was clueless to.
Ebay is my next area to look but they must show up in waves. Either there or they're not but either way I'm getting outbid on the ones I suspect are functioning. The ones I've shy'd away from don't get much attention. Mainly, if it's too good to be true then it must be.
I remember articles as a child about building DLs. I got a couple of old paint cans. What else do I need?

Hunt around. I picked my up from a local club's swapsheet. For $5. My first (And only so far) Heathkit :)

[W3WN]

Last hamfest I attended, I must have jusy missed them all. Every table that looked interesting, I inquired about a dummy load and the answer from everyone was, "You just missed it. I just sold it." Somewhere that day, a lone ham was totin' home all the DLs. Either that or there was an inside joke going on that I was clueless to.
Ebay is my next area to look but they must show up in waves. Either they're there or they're not but either way I'm getting outbid on the ones I suspect are functioning. The ones I've shy'd away from don't get much attention. Mainly, if it's too good to be true then it must be.
I remember articles as a child about building DLs. I got a couple of old paint cans. What else do I need?
Mendelsson's had a bunch of solid state medium power (up to 300 W) DL's in their tent at Dayton. I think the cost was about $25 each.

I almost bought one... certainly would take up less space than the Cantenna, and I could mount it out of sight, but just saw no point to it at present. Now next year, if I have a little more shekels to spend...

[kf0rt]

What else do I need?

For the paint can variety, some 50 0hm resistors of the "big honkin'" variety, an SO-239 and about a gallon of transformer oil.

Some buddies made one of those out of a 20 gallon (?) drum once many years ago. Not sure how much it could handle, but RG-8 would get soft and spongy before you could detect the drum getting warm.

[KG4CGC]

For the paint can variety, some 50 0hm resistors of the "big honkin'" variety, an SO-239 and about a gallon of transformer oil.

Some buddies made one of those out of a 20 gallon (?) drum once many years ago. Not sure how much it could handle, but RG-8 would get soft and spongy before you could detect the drum getting warm.
I recall a guy on QRZ classifieds selling those resistors (or some such similar) for 10 bucks a pop and said he'd be at Dayton.
I'll keep looking.

[w3bny]

I got 3 of the 300w air cooled ones on a package deal for like 30 bucks and keep one them on a port of my antenna switch. Can swap over to DL straight from the transceiver with a snap of the switch. And I do have a MFJ bucket-o-oil too. If I have to do repeated testing.but yeah, I agree...dummy loads are cheap and your friend.

[KB3LAZ]

Dummy load or loaded dummy? Just have your buddy stick his finger in the SO239 of your amp and they key up. You then have a loaded dummy, extra crispy. But yes every ham should have a dummy load.

[N8YX]

I've got a number of them in the shack - 4 DL1000 w/FA-7 fans connected to each of the station antenna tuners; a couple of small Diamond 30w units for use as a fail-safe on my amplifier feed-matrix switch and a Cantenna/B&W air-cooled pair for use on the test bench.

If your tuner has a "dummy load" (straight through) position, I highly advise picking up a unit which is rated for the maximum amount of power your station is capable of producing. Then connect the load up and use it when tuning your amp, for example. Saves wear and tear on your t00bs.

[ka4dpo]

I have a Cantenna that I got at a hamfest for $5.00 about 35 years ago. It's butt ugly in an old paint can with a Ballantine Ale sticker on it but it was the Best five bucks I ever spent.

[suddenseer]

Many new hams have this one...


























http://netbestshopping.com/RMA_zip/RMA_zip/25307.gif

[kf0rt]

A suppository?

[suddenseer]

http://www.walker1812.com/dev/photos/misc/rubberducks/duck07.jpg

[WØTKX]

DIY Paint-Can Dummy Load (http://www.k4eaa.com/dummy.html)

[w2amr]

For the paint can variety, some 50 0hm resistors of the "big honkin'" variety, an SO-239 and about a gallon of transformer oil.

Dump in a can of STP too, It will help keep them electrons sliding along. :yes:

[KG4CGC]

DIY Paint-Can Dummy Load (http://www.k4eaa.com/dummy.html)
Nice project. Who carries those resistors?

[kf0rt]

Nice project. Who carries those resistors?

1K, 3 Watt? Mouser seems to have a pretty good selection:
http://www.mouser.com/Passive-Components/Resistors/Power-Resistors-with-Leads/_/N-2gra1?P=1z0vkp6Z1z0vo2a

[KG4CGC]

Thanks. Should I add a 5% mix of KY to the mineral oil and STP in the can?

[WØTKX]

Astroglide.

http://www.threadbombing.com/data/media/2/animated99.gif (http://www.threadbombing.com/details.php?image_id=1422)

[W3WN]

I have a Cantenna that I got at a hamfest for $5.00 about 35 years ago. It's butt ugly in an old paint can with a Ballantine Ale sticker on it but it was the Best five bucks I ever spent.

The Ballantine sticker alone was worth that... I miss that brew...

[KG4CGC]

The Ballantine sticker alone was worth that... I miss that brew...
Ballentine (sp) did a short stint here in the South many years ago. Guaranteed that at least 2 out of 6 cans of a 6 pack would be flat. Don't ask me why. Short lived appearance but I did try it. Surprisingly, Goebel was around for a short time and was really good but only available at a small, obscure gas station in Taylors.

[W3WN]

Ballentine (sp) did a short stint here in the South many years ago. Guaranteed that at least 2 out of 6 cans of a 6 pack would be flat. Don't ask me why. Short lived appearance but I did try it. Surprisingly, Goebel was around for a short time and was really good but only available at a small, obscure gas station in Taylors.

Growing up, my Dad would always buy Rhinegold or Ballentine. One of the two was brewed down in Orange NJ, so it was always "fresh."

I think one of the two was revived... or at least someone bought the formula and was trying to brew it again... but it's just not the same.

I hear locally that Iron City and IC Light are actually drinkable, now that they moved production from the Lawrenceville section of Pittsburgh to the old Rolling Rock brewery in Latrobe. Makes a difference when your water source is "clear montain springs" and not city water out of the river sludge.

Meanwhile RR, which was sold to Anheiser-Busch (the brew not the brewery) is now brewed in Newark NJ. I hear it's not the same as it used to be since A-B bought them from InBev... who now owns A-B and has put RR up for sale, so you know where that's going...

[kf0rt]

Thanks. Should I add a 5% mix of KY to the mineral oil and STP in the can?

I'd probably just stick with the mineral oil.

Neat little project, though, and I like the idea of using a quart can. 60W worth of resistors and all that oil cooling, should be a perfect little load for any "modern" 100W transmitter. Cheap and easy to build. Did some digging into higher wattage resistors, but they all seemed more expensive than the parallel idea.

Probably a non-issue, but I'm wondering if 5% tolerance is good enough...?

[KG4CGC]

Growing up, my Dad would always buy Rhinegold or Ballentine. One of the two was brewed down in Orange NJ, so it was always "fresh."

I think one of the two was revived... or at least someone bought the formula and was trying to brew it again... but it's just not the same.

I hear locally that Iron City and IC Light are actually drinkable, now that they moved production from the Lawrenceville section of Pittsburgh to the old Rolling Rock brewery in Latrobe. Makes a difference when your water source is "clear montain springs" and not city water out of the river sludge.

Meanwhile RR, which was sold to Anheiser-Busch (the brew not the brewery) is now brewed in Newark NJ. I hear it's not the same as it used to be since A-B bought them from InBev... who now owns A-B and has put RR up for sale, so you know where that's going...
It will be another homogenized swill for the masses. I remember enough of RR to recall that you could taste the rice.

[N5RLR]

Back on topic... :-P

For the *ahem* adventurous: Saltwater Dummy Load [click] (http://www.qsl.net/k5lxp/projects/SaltLoad/SaltLoad.html) 8)

http://www.qsl.net/k5lxp/projects/SaltLoad/s_807Load.jpg

[KA5PIU]

Hello.

You can buy the resistors from the website.
And, yes, pure mineral oil is the way to go, 100% nontoxic that way.
In fact, spray the resistors with food grade epoxy after soldering with plumbers "lead" and washing the flux with water and a good drying job.
Use a food grade "paint" can and you are all set.

[n2ize]

Dummy load = light bulb.

[KG4CGC]

Dummy load = light bulb.
If this were 1944, then I would agree.

[n2ize]

If this were 1944, then I would agree.

It's basically what I use when I test any transmitter in the 100 watt ( and sometime higher) category. Of course, most of my equipment dates back to the 40's - 50's.

[KG4CGC]

It's basically what I use when I test any transmitter in the 100 watt ( and sometime higher) category. Of course, most of my equipment dates back to the 40's - 50's.
And thus, you are technologically compliant with the era of your gear.

[n2ize]

And thus, you are technologically compliant with the era of your gear.

This place is a combo of 20th century 1940's - 50's with a smattering of the 12th century mixed in.

[KG4CGC]

This place is a combo of 20th century 1940's - 50's with a smattering of the 12th century mixed in.
In otherwords, it's dark and dank with the occasional glow of, radio.

[AA0CX]

I'd been looking for one too. Finally just bought one!

[KG4CGC]

I'd been looking for one too. Finally just bought one!
Congratulations! Which one did you decide on?

[KA5PIU]

Hello.

And for your light bulb needs.
http://www.ferrowatt.com/products.php#9
I have had woodworkers produce wooden boxes that I have mounted just such light bulbs on.
I have also produced both telephones and radios based on DIY guides published by the USDA in the past.
In essence, I am a farm kid, one who first learned this in a communist country, but a farm kid.
So building, or rebuilding, radios has great appeal to me.

[W1GUH]

What's fun is to have an analyzer and a dummy load and hook up the dummy load with jumper picked up at random at a hamfest. Then expect to see a nice, flat 1:1 from DC to daylight. But I didn't, I saw a wierd pattern of impedances and SWR's. After a few WTF's? I noticed I'd gotten 72 ohm coax. DUH.

The trouble with using a light bulb is the photons emitted from tungsten while excited by RF are "different" than ordinary, 60 cycle AC photons and have been known to cause weird effects in laboratory rats. They get all freaked-out with wild eyes and sometimes engage in deviant behavior. I'd say, play it safe and use those bulbs for what they were intended for.

One explanation why BA collectors can sometimes seem so deviant.