[Amps] Dummy Load Blues

[Gary Smith]

The method of keeping the oily goo off of the floor is identical as to how I have done it for many years.  Same heathkit Cantenna too.


73,

Gary...wa6fgi




>________________________________
> From: Jerry Kaidor <jerry at tr2.com>
>To: amps at contesting.com 
>Sent: Thursday, June 14, 2012 4:54 PM
>Subject: [Amps] Dummy Load Blues
> 
>Hello,
>
>   To mess with amps, a good dummy load is a must.  I went to my storage,
>and pulled out a Cantenna of unknown provenance that I had purchased about
>30 years ago at a flea market.  Not knowing what was in it, I assume it's
>poisonous PCB transformer oil.  I had kept the dummy load in a plastic bucket
>with a hole for the coax, sealed with coax seal.  Now I figured I'd
>dispose of the old oil, clean it out, and put in fresh mineral oil.  What
>a mess!
>
>   OK, the old oil is gone; it'll be headed to the local hazardous waste
>dropoff.  The guts are all washed out in hot water and detergent.  The
>heathkit can is toast - rusty and leaking.  The silver
>straps around each end of the resistor are broken.  So I can reconstitute
>this thing with new silver straps ( luckily I have some silver sheet
>laying around ).  And the can - can be replaced with an ordinary one from
>the paint factory.  Only trouble with that is - 1 gallon paint cans are
>now *plastic*, not metal.  I guess it'll still work, just the heat
>transfer won't be quite as good.
>
>   I also scored a 250W load cheap on Ebay.  Seller said it came out of a
>cell phone installation.  I popped it open - the resistor is the size
>of a postage stamp!  I was messing with one of my SB2-LA's, used that
>load - figured a momentary toot from the amp wouldn't hurt it.  I was
>wrong.  Apparently these little resistors are not only heat limited,
>but *voltage* limited.  I hit transmit, there was a small *pop* and a
>puff of smoke.  Hole burned right through it.
>
>   There are similar load resistors on sale on Ebay - 800W for IIRC $40. 
>But that's just the resistor, you have to bond it to a heatsink.  I
>have
>the heatsink from the defunct 250W load - I could machine off a big enough
>flat spot for the 800W resistor.... failing that, I have a really big heat
>sink in my junk.
>
>                          - Jerry Kaidor, KF6VB
>
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