[Heathkit] FS: Heath Cantenna - Caution About The Oil

Sun May 10 01:08:40 EDT 2015

>From the 1985 Radio Amateur's Hanbook, pp.34-17 to 34-19:

Selection of the coolant for the resistor involved a lengthly
investigation. The use of PCB transformer oils is illegal and involves
a serious health hazard. The investigation did identify several
modern-day transformer and heat transfer oils that could be used, but
none are available for purchase in any quantity less than a 55-gallon
drum. Transformer oil has lower viscosity. That means lower resistor
tepmeratures, but at the penalty of using an oil with a 140 to 150 C
flash point (vaporization temperature). Transformer oil is also treated
to remove water, but maintaining this dry condition is difficult and
expensive. Calculations of the fluid heat transfer show that turbulent
nature convection flow exists for rated power levels. The use of higher
viscosity oil produces higher resistor temperatures, but the gain in
flash point temperature is greater than the rise in resistor
temperature. Oils designed for heat transfer have flash points in the
230 to 250 C region.

  Heat transfer oils are composed predominantly of mineral oil. Highly
refined or medicinal mineral oil has a usably high flash point but at
an undesirably high cost. Heat transfer oils contain small amounts of
rust and oxidation inhibitors, making them preferable to mineral oils.
Heat transfer oils are not available in small quantities, but in at
least one case the very same product is relabeled and sold in 5 gallon
cans for service as a "turbine oil". That product is sold by TEXACO
distributors as Regal Oil R&O No. 46.

  Use of automotive and transmission oils is undesirable. They are
composed of a wide mixture of oils with different flash points. Motor
oil additives will damage the metal platings on an RF resistor. There
is no danger in the short term use of automotive oils, but the
long-term effects are a problem. Further, there are no economic
advantages with automotive oils, as they cost as much as turbine oil.

--from the "Super Dummy" construction article, designed by ARRL TA Dick
Jansson, WD4FAB.

On Sat, 9 May 2015 17:34:57 -0700, Chuck Penson wrote:

>With transformer oil the Cantenna will handle 1000 watts for 10 minutes. With mineral oil the 1KW rating drops to less than a minute. 

>Chuck / WA7ZZE 

>"Remain open to the possibility of the fantastic." -- Terry Hansen

>> On May 9, 2015, at 2:53 PM, RAY FRIESS <rayfrijr at msn.com> wrote:
>> 
>> Best thing to use in them is mineral oil.   Go to your nearest farm supply store, like IFA, and get a gallon.
>> 
>> 
>>> Date: Sat, 9 May 2015 16:59:08 -0400
>>> From: wd8arz at comcast.net
>>> To: heathkit at mailman.qth.net
>>> Subject: Re: [Heathkit] FS:  Heath  Cantenna - Caution About The Oil
>>> 
>>> =========
>>> Just an FYI
>>> =========
>>> 
>>> Original Heath Kit Cantenna's were built by the purchaser from Heath, 
>>> with instructions on filling it with Transformer Oil from your local 
>>> power utility if possible ...... and most were, as I did with mine.
>>> 
>>> Over the years we learned that the transformer oil was a toxic agent, 
>>> and was not to be handled, and it was recommended to remove it from the 
>>> dummy load. Removal of that oil and proper disposal was required, and I 
>>> did so with mine.
>>> 
>>> Replacement oil was normal over the counter mineral oil. It would derate 
>>> the power / time handling spec for the cantenna, but for those of us 
>>> running barefoot, that was a none issue.
>>> 
>>> =========
>>> Just an FYI
>>> =========
>>> http://www.epa.gov/region9/pcbs/faq.html
>>> ***
>>> What are Polychlorinated Biphenyls?
>>> 
>>> The manufacture of PCBs was stopped in the U.S. in 1977 because of 
>>> evidence they build up in the environment and can cause harmful health 
>>> effects.
>>> 
>>> Polychlorinated biphenyls (PCBs) are synthetic chemicals which are no 
>>> longer produced in the United States, but are still found in the 
>>> environment. PCBs have been used as coolants and lubricants in 
>>> transformers, capacitors, and other electrical equipment because they 
>>> don't burn easily and are good insulators. The manufacture of PCBs was 
>>> stopped in the U.S. in 1977 because of evidence they build up in the 
>>> environment and can cause harmful health effects. Products made before 
>>> 1977 that may contain PCBs include old fluorescent lighting fixtures and 
>>> electrical devices containing PCB capacitors and hydraulic oils.
>>> ***
>>> 
>>> 73 from Bill - WD8ARZ
>>> 
>>>> On 5/9/2015 3:37 PM, Walter Treftz via Heathkit wrote:
>>>> Got a Heath "Cantenna" dummy load out of an estate. Price: $25 pluspostage, with or without oil. Located in Hernando (Ocala/Inverness area) and if bought, can deliver free to a mutually-attended hamfest.(if using shipping, can wrap it inside several trash bags so the oil cango with it). Pix avail if I can get my kid (the family photo-bug) to take them.73 Walt (N4GL)(352) 637-1755
>>> 
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>>                         
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