'Heavy' or 'Light' mineral oil for Cantenna?

[Dave Mueller]

The mineral oil used in the "small", ie up to 1.5KW, Bird loads has a viscosity of 12 (CST @ 104 deg F).  I'm not sure if that's light or heavy.

There's two important specs: heat transfer capability and dielectric constant.  For intermittent HF use, I don't think you'll see the difference between either.  If you're going to cook the load at 500MHz and 1KW for an hour, then I'd worry.

For the small loads, we buy food grade mineral oil from the pharmacy.  They check out OK on the network analyzer up to 1GHz.

73,
Dave AA3EE

>From: Robert Myers <rsmyers at ROGERS.COM>
>Date: 2007/04/18 Wed PM 09:50:46 CDT
>To: HEATH at LISTSERV.TEMPE.GOV
>Subject: 'Heavy' or 'Light' mineral oil for Cantenna?

>Hi all,
>
>Question RE: Best 'Cantenna' (Heathkit HN-31) mineral oil type to use.
>
>I have an HN-31 Cantenna (the original one with the circuitry on top for
>measuring relative power).  
>
>I can fill it with so-called 'heavy' mineral oil (more viscous), or
>'light' mineral oil (less viscous).  I have both types available.  Both
>are easily bought at the pharmacy and elsewhere.
>
>Can someone tell me which would be the better choice of the two?
>
>[Note: I don't want to use transformer oil or anything else -- I just
>want to consider these two types of mineral oils for the moment.]
>
>Does anyone have a definitive answer?
>
>Thanks,
>-- Rob Myers,
>VE3JQL.
>
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