Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: Prev 1 2 [3] 4 5 Next   Go Down
  Print  
Author Topic: air vs oil dummy load ?  (Read 4910 times)
KC4ZGP
Member

Posts: 1961




Ignore
« Reply #30 on: August 27, 2018, 05:45:57 AM »


Herr Booty Monster,

Alrighty. Welcome to the hobby. Anyone can learn anything. Get that license man!

An MFJ-259B. Alrighty. I use a RigExperts AA-30. Both great antenna tools.

Vector 4000. OK. Lengthen or shorten elements for other bands. Your MFJ-259B will guide you.

Palomar 300A amplifier. OK. Legal to use it if licensed to use it.

I have an idea. Build a delta loop or dipole for 27.185MHz, middle of the citizen's band. Examine differences via the
MFJ-259B. You'll have to 'dig' in the books to build either antenna.

That's ham radio. And like I said, get that license man!

Kraus

Logged
KC4ZGP
Member

Posts: 1961




Ignore
« Reply #31 on: August 27, 2018, 05:58:46 AM »

probably a stupid question , but ......
could a mfj-264 be submerged in a gallon of oil for longer duty cycle ?


Yes you can. The 'paint can' dummy loads are an MFJ-264 resistor element submerged in oil. Pennzoil
10W-30 or thicker will work. The oil just dissipates heat.

Have fun experimenting.

Kraus

Logged
W8JX
Member

Posts: 13268




Ignore
« Reply #32 on: August 27, 2018, 07:46:19 AM »

I would use straight weight SA rated 10w or 20w20 non detergent oil if you use motor oil
Logged

--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
KE6EE
Member

Posts: 2816




Ignore
« Reply #33 on: August 27, 2018, 08:14:00 AM »

Back in the day it was a club fundraiser to make "1kW" saltwater loads out of plastic gallon pickle jars from a restaurant, and the test criteria was full keydown from a TL-922 for 10 minutes which it easily handled.
Mark K5LXP
Albuquerque, NM
 


Salt water dummy loads remind me of my novice days when all I had was a light bulb dummy load. I had a long CW QSO with a ham in Germany using that "dummy load". It was a great grade school learning experience.

- Glenn W9IQ

Very amusing!

Using a metal container and some peanut or canola oil, a good fundraiser event might be to see who could fry a donut with a "dummy" deep fryer load.

I remember the light bulb dummy loads I used. Very exciting to see the
bulb brighten as I tuned the pi-network of my 807-powered rig. Such a device really should be called an "enlightened dummy load."
Logged
K6BRN
Member

Posts: 1352




Ignore
« Reply #34 on: August 27, 2018, 08:32:42 AM »

Mark:

So, you really think standing next to an open bucket of conductive salt water while running a KW of RF through it is a wise move?  One that could spill at a moment's notice, so that you are standing  in it's conductive contents in the middle of an electical wiring jungle and ever-present RF voltages   Or whose container could shatter if you were to use glass as the the pretty ignorant person in the link you supplied did?  And you think the impedance will be stable and well controlled?  And you don't think that salt and water reacts with metal to degrade it (you don't have a boat, do you?)

Are you applying for the 2018 Darwin award?

No - it's NOT a good approach and that's why you will NEVER see this done commercially, or even in OTC amateur equipment.  The potential liability is sky high and the performance will be predictably poor.  This is just a BAD idea with strong safety risks, which is why I'm just a little excited about it.

You should have a disclaimer:  "Don't try this at home" just to protect yourself from the liability of some hapless elf on this forum repeating the experiment and being electrocuted.

As I said... as a demo, hey, wow, interesting.  And stand back, please.  It's like Glenn's light bulb...  "Wow!  See it glow!".  Now put it away before you hurt someone and buy or build the real thing (using a safe and stable approach - NOT a coax dipped into water bucket or glass jar full of salt water).

Be smart.  Stay safe.

Brian - K6BRN
Logged
W8JX
Member

Posts: 13268




Ignore
« Reply #35 on: August 27, 2018, 08:39:52 AM »

I remember the light bulb dummy loads I used. Very exciting to see the
bulb brighten as I tuned the pi-network of my 807-powered rig. Such a device really should be called an "enlightened dummy load."

I remember when I built my Heathkit HW16 about 49 years ago. It recommended using a light bulb (75 watt I think) as a dummy load when aligning transmitter.
Logged

--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
K8AXW
Member

Posts: 7042




Ignore
« Reply #36 on: August 27, 2018, 09:08:56 AM »

JX:  Right you are!  Have you noticed a tendency to overthink everything these days?  I fell into this trap several years ago when I wanted a circuit to perform a function which I now forget....spent hours designing a solid state circuit and before I could put it together I realized what I wanted could be done with a .....wait for it ..... a simple relay!

I said to myself. "Myself, what the hell's wrong with you?  KISS:  Keep It Simple Stupid!

In this case, experiment if you wish then publish your findings.  Don't ask, "what if?"
Logged

A Pessimist is Never Disappointed!
K5LXP
Member

Posts: 6169


WWW

Ignore
« Reply #37 on: August 27, 2018, 09:31:59 AM »

standing next to an open bucket of conductive salt water

It's not open, it has a lid.  That's where the connector and conductors are mounted.

Quote
One that could spill at a moment's notice,

Not with a lid on it.  Never made one with a bucket but the jars are designed to hold liquid for their original contents and seal quite well.

Quote
whose container could shatter if you were to use glass

Hasn't happened in a few decades so far.  Not impossible though I guess.  If you're accident prone, use plastic.

Quote
And you think the impedance will be stable and well controlled?

Yes, very much so.   The solution isn't terribly sensitive as far a concentration and as long as nothing evaporates (see "lid" above) then it just stays that way.  For years.

Quote
  And you don't think that salt and water reacts with metal to degrade it

I have observed that the copper turns dark (like a penny) but that's about it.  And if you use steel screws and nuts on the SO-239 they will rust eventually.  Nylon or stainless hardware takes care of that.  Or just use an extra large blob of silicone on the connector.

Quote
Are you applying for the 2018 Darwin award?

I didn't bother applying after I found out you have to do something much worse than running with scissors.

Quote
No - it's NOT a good approach

Never said it was perfect.  But for the time, money and complexity it sure works pretty good.

Quote
This is just a BAD idea with strong safety risks

No more risky than anything else you do with electricity.  Common sense and basic awareness will take you a long way.  As a product you have to design for the lowest common denominator, which is why you have to sell hair dryers with a label that shows a bathtub with a circle and slash over it, because there's someone out there that will try it.  But, this isn't a product.  Sorry if this is an affront to your sensibilities, feel free to trumpet my lack of caring and idiocy for suggesting such folly.  Meanwhile my saltwater loads on the shelf are a great curiosity and topic of discussion with visitors of my shack and come in handy for testing from time to time when I'm not busy running with scissors. 

Mark K5LXP
Albuquerque, NM
 
Logged
K5LXP
Member

Posts: 6169


WWW

Ignore
« Reply #38 on: August 27, 2018, 09:40:32 AM »

ratio of water to input power is directly proportional so 1 gallon at 1 kW would also boil in about the same amount of time.

As an empircal data point, there's a graph on my site that shows actual temperature vs 100W input with ~22oz of water which takes into account some degree of convection/conduction to ambient.  Haven't done the calculation but I wonder if that correlates to your 1gal/1kW conclusion.  When we built and tested the 1 gallon ones I'm not sure if it was exactly one gallon, might have been more (whatever the freebie restaurant pickle jars were) and I recall they never boiled after 10 minutes. 

Mark K5LXP
Albuquerque, NM
 

Logged
K6BRN
Member

Posts: 1352




Ignore
« Reply #39 on: August 27, 2018, 11:34:10 AM »

Mark:

I can't fix stupid.  Only you can do that.  It's your life.  But please do NOT try convince some poor hapless fool that a multi-gallon salt water dummy load built out of a plastic bucket (ummm... with a lid - GREAT!) from Home Depot is in any way safe or wise around the "shack".

And a flimsy plastic bucket of several gallons of electrified salt water next to energized RF electronics and AC lines IS more dangerous than running with scissors.  But than, a Darwin candidate wouldn't know that.

On a qualitive note, a person who had made good choices in life would probably never need or consider building what is essentially a portable electric chair into their operating position.  They could afford the hundred bucks  +/- needed to buy or build a safe one.  Thomas Edison pretty much proved what could happen over a century ago with AC and water.  You really do not have to repeat the experiment.

As a sanity test, try proposing your approach at work and bring in an OSHA rep to give it a "thumbs-up",  They could probably use the comic relief.

Once again - SAFETY OVER STUPIDITY.

Best Regards,

Brian - K6BRN
Logged
K6JH
Member

Posts: 526




Ignore
« Reply #40 on: August 27, 2018, 12:58:47 PM »

I would use straight weight SA rated 10w or 20w20 non detergent oil if you use motor oil


Wow! An oil thread on e-Ham!

I would go for Mobil-1 synthetic myself.  Cheesy
Logged

73
Jim K6JH
W9CN
Member

Posts: 137




Ignore
« Reply #41 on: August 27, 2018, 01:32:48 PM »

I would use straight weight SA rated 10w or 20w20 non detergent oil if you use motor oil

Wow! An oil thread on e-Ham!

I would go for Mobil-1 synthetic myself.  Cheesy

Mobile 1 rocks.  Especially if you live someplace where it gets to negative temps in the winter.  It doesn't turn to molasses at 10F below.  I have four vehicles with over 120K on them all running Mobile 1. 
Logged
KM1H
Member

Posts: 5550




Ignore
« Reply #42 on: August 27, 2018, 01:37:03 PM »

My first experience with a dummy load and wattmeter was with the B&W 334A that was used at National Radio almost 10 years after I was licensed, built many Heathkit rigs for myself and others plus a couple of KW amps while still in HS. Lightbulbs and OTA were the only methods available to the po boys back then.

Carl
Logged
KM1H
Member

Posts: 5550




Ignore
« Reply #43 on: August 27, 2018, 01:48:03 PM »

Quote
Mobile 1 rocks.  Especially if you live someplace where it gets to negative temps in the winter.  It doesn't turn to molasses at 10F below.  I have four vehicles with over 120K on them all running Mobile 1.

Looooong before Mobil 1...not Mobile, the cold weather formula was a quart or two of kerosene or diesel added to the non detergent 30W in the crankcase; this was also mentioned in owners manuals.

It was always fun getting a 6V vehicle started at -20F or so and especially the always gummed up flathead Ford V-8's. When I moved up to MA/NH a 8V tractor battery and adjustable regulator were a big help. Kind of rough on headlights but they were only $.10-to .25 in a junkyard.

In the early 2000's I used a 12V battery to start a 54 Ford F-350 with a V8 Y Block and a transfer switch to 6V for driving.

Carl
Logged
W9CN
Member

Posts: 137




Ignore
« Reply #44 on: August 27, 2018, 02:34:02 PM »

Quote
Mobile 1 rocks.  Especially if you live someplace where it gets to negative temps in the winter.  It doesn't turn to molasses at 10F below.  I have four vehicles with over 120K on them all running Mobile 1.

Looooong before Mobil 1...not Mobile, the cold weather formula was a quart or two of kerosene or diesel added to the non detergent 30W in the crankcase; this was also mentioned in owners manuals.

It was always fun getting a 6V vehicle started at -20F or so and especially the always gummed up flathead Ford V-8's. When I moved up to MA/NH a 8V tractor battery and adjustable regulator were a big help. Kind of rough on headlights but they were only $.10-to .25 in a junkyard.

In the early 2000's I used a 12V battery to start a 54 Ford F-350 with a V8 Y Block and a transfer switch to 6V for driving.

Carl

Autocorrect strikes again with the Mobil/Mobile.
Logged
Pages: Prev 1 2 [3] 4 5 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!