1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Dummy Load plans and pics please ;) My Cantenna finnaly rotted through :(

Discussion in 'Home Brew' started by WINKDOGG, Dec 3, 2019.

  1. WINKDOGG

    WINKDOGG President CFO & CPFO WorldwideDX Radio

    Joined:
    Feb 21, 2011
    Messages:
    194
    Likes Received:
    225
    Like the title says I had a very old rusty Heath-Kit 1000 watt Cantenna dummy load but it finally started leaking and showed a dead short ;( I disposed of it for obvious reasons but im mad I did not pop the lid and keep it for a rebuild ;( . I have found some plans and they are ok but Im just wondering should I buy a new one , a kit , or scratch build one ? I ran the cantenna for 20+ years with a gallon of transmission fluid in it and it was great but the time has come for a fresh dummy load ! I have seen some salt water diy loads but mostly rated around 200 watts at 50 ohms . Im looking to build a 1500-2000 watt peak dummy load from the parts pile ! If its just cheaper tom buy one , guess what I may still build my own lol



    Any links , thoughts or ideas would be great ! Im hoping to get a nice set of plans and I will do a build video and post it for all to see ! I have a shiny new 1 gallon paint can , pl259 chassis connector as well as assorted high power resistors , solid copper wire , and all types of goodies to build it with but would like a tried and true setup I know I can trust!

    Thanks again as always , 73's 4-2-Zero Brian in NJ
     

  2. Dmans

    Dmans Sr. Member

    Joined:
    Jan 22, 2017
    Messages:
    691
    Likes Received:
    613
    WINKDOGG,
    Build your own but use mineral oil in it. (Available from a drug store)
    Or keep a fire extinguisher handy!

    Good Luck

    73
    David
     
    S&W357 and Captain Kilowatt like this.
  3. BJ radionut

    BJ radionut Supporting Member and 6m addict

    Joined:
    May 9, 2008
    Messages:
    2,618
    Likes Received:
    2,177
  4. blasphemy000

    blasphemy000 Active Member

    Joined:
    Mar 31, 2017
    Messages:
    69
    Likes Received:
    102
     
    Shockwave likes this.
  5. kopcicle

    kopcicle Sr. Member

    Joined:
    Feb 17, 2016
    Messages:
    1,536
    Likes Received:
    2,068
    https://www.ebay.com/itm/1650W-50Oh...969872?hash=item2f0518bb90:g:UO8AAOSwaP5cm0rk

    I think it goes without saying that you would need a YUUUUUGE heatsink.

    Note: Because of the need for a good sized flange for a heat path the possibilities for more economical 50 Ohm parts in series/parallel are limited by total capacitance. It might be better to simply series resistors and use a broad band transformer for higher wattage. This has the additional advantage of placing a high wattage 4:1 or 6:1 transformer in the shack for other purposes .
     
    #5 kopcicle, Dec 3, 2019
    Last edited: Dec 3, 2019
  6. Road Squawker

    Road Squawker Sr. Member

    Joined:
    Jan 19, 2011
    Messages:
    1,782
    Likes Received:
    1,214
    You will get a lot of strange looks from the cashier if you buy a gallon at a drug store,..... and pay waaaaaay to much.
    Walgreens 16 oz for $6.00.. about$45/gal

    Get it from an Ag. type store like Tractor Supply,...... its a lot cheaper ($20.00/gal) and they sell it by the gallon all the time.
     
    Wildbill63, sunbulls and 2NC995 like this.
  7. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

    Joined:
    May 1, 2013
    Messages:
    4,565
    Likes Received:
    4,474
    $130.00 FOR ONE RESISTOR? Buy the new CanTenna for $45.00 of $50.00.(Very old price)
     
    #7 Tallman, Dec 3, 2019
    Last edited: Dec 4, 2019
    binrat likes this.
  8. blasphemy000

    blasphemy000 Active Member

    Joined:
    Mar 31, 2017
    Messages:
    69
    Likes Received:
    102
    If you really must do it yourself. The video I posted above is a design that works perfectly fine, and as far as I know, is very similar to the Heathkit can internals. I never had mine open. That 100W, 50 Ohm, carbon rod resistor will handle 1000W ICAS when submerged in mineral oil, no problem at all. Those resistors are pretty cheap too if I'm not mistaken. Unless you're doing high power VHF or UHF, it's doubtful that you need any type of specialty resistor.
     
    Captain Kilowatt likes this.
  9. Dmans

    Dmans Sr. Member

    Joined:
    Jan 22, 2017
    Messages:
    691
    Likes Received:
    613
  10. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    15,933
    Likes Received:
    8,553

    That's crazy. I bought two 100 ohm 800 watt resistors for twenty-something each off Ebay. Less than $50 for the pair delivered.
     
    2NC995 likes this.
  11. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

    Joined:
    May 1, 2013
    Messages:
    4,565
    Likes Received:
    4,474
  12. Shockwave

    Shockwave Sr. Member

    Joined:
    Sep 19, 2009
    Messages:
    3,138
    Likes Received:
    1,802
    My original Heathkit can top and resistor are now in its third new can of oil after 40 years. The can takes about 20 years for the bottom to rot out depending on humidity in your shack. Oddly enough, it's drifted down in value to about 45 ohms after all this time. It's the one that was used with the least regard to rated specs... Still close enough to use for most applications.
     
    blasphemy000 likes this.
  13. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    3,254
    Likes Received:
    3,375
    A fresh 1-gallon can is all you need unless it was operated with the oil level below the resistor. That would probably damage the resistor. A check with a meter will reveal that.

    73
     
    2NC995 likes this.
  14. Pioneer621

    Pioneer621 Member

    Joined:
    Mar 14, 2009
    Messages:
    56
    Likes Received:
    21
    This thread made me check my Cantenna bottom, not sure I ever have since buying it from a hamfest. Looks like the bottom of mine may have leaked in the past and someone soldered it closed?

    Mine was cheap and although the guy said it worked fine, when I got home the resistor measured 80 or 90 ohms and did not give a good SWR at all, makes sense if it leaked and was ran like that. I installed 20 1-watt carbon resistors just to use it (that I already had), but they have held up to abuse over the years. I think the biggest amp I ran into it was a Maverick 250, lots of other smaller amps, have not fried the resistors yet.

    The top lid looks reasonably okay, so if it does leak I'll just swap the can. I'm in the process of moving and happened to have this on the basement steps and wanted to see if the bottom was rusty.

    I'll have to make sure I keep an eye on this for leaks, something I never thought about before to be honest.

    IMG_2807.JPG IMG_2820.JPG
     
    Chevboy0167 likes this.

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!