[TowerTalk] insulating oil (also PCB issues) was Re: HN-31 Heathkit Dummy Load

Jim Lux jimlux at earthlink.net
Tue Apr 4 18:16:13 EDT 2006

At 02:34 PM 4/4/2006, kb0fhp at comcast.net wrote:
>Personally, the use of quench oils used in heat treating also works 
>well.  It is typically a high grade paraffinic mineral oil, with oxidation 
>additives added for this severe duty.  These can be obtained from either 
>supply houses like Brownells (a gunsmithing supply company), Quench oil 
>manufacturers (like Houghton International - my employer), or small oil 
>supply distributers (usually found locally).  The oils can also be 
>obtained either new or used (which would work fine) from a local 
>commercial heat treater.
>Does any one have the viscosity specifications of the transformer oil used 
>(cSt or SUS)?


9.1 centistokes @ 40C, 2.3 cSt at @100C
55.8 SUS @ 40C, 33.9 SUS @100C

For comparison, USP White Mineral Oil seems to be available in SUS at 100F 
from 55 to 1000, so Diala AX is about the same viscosity (at 40C) as the 
least viscous USP White Mineral oil.

I suspect that the "mineral oil" rating for the Cantenna loads is based on 
a more viscous mineral oil (baby oil, etc.  seem to be in the 150-300 range)
For instance the various kinds of Drakeol(tm) range from 35 to 105 cSt at 40C

As far as quenching oils goes, you'd know better than any of us, but my 
handy-dandy reference chart gave 20 cSt @40C for Shell Voluta H201 
quenching oil (that's the least viscous.. some have viscosities up to 
243cSt at 40C (VH401), so they're somewhat more viscous than transformer oil.

I won't say that Diala AX pours just like water, but it's pretty fluid 
stuff.  A lot less viscous than, say, motor oil or cooking oil.  Maybe like 


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