[R-390] Re: Pearl tube shields

[b w]

You may find it easier to buy one of the hand held RC plane temperature=20
sensors. They run about $25 and are used to get the temps of running=20
engine parts. It should be fairly accurate if held around the tubes at=20
various spots.



Barry non-Hauser


>Interesting thread: reducing operating tube temperatures is one maneuver=
 that will definitely prolong their life. Note that there are TWO types o=
f IERC shields, one that merely slips over the the JAN socket, and one th=
at actually mates mechanically to a special add-on sleeve bolted to the s=
ocket. The latter has an advantage in that a large area thermal connectio=
n is made to the chassis for conduction of heat away from the tube. This =
arrangement makes the most sense for those tubes below the chassis in the=
 R-390 series, and not all that advantageous for those above the chassis.=
 As Roy correctly points out, a fan is far more important to dissipate he=
at away from the tubes. On the market today are 80cm ball-bearing fans th=
at are incredibly quiet that can be mounted strategically to dissipate he=
at... most useful for those of us that have the unit housed in a cabinet.=
 My preference would be to mount the receiver in a ventilated rack with b=
oth top and bottom covers OFF.
>
>Stictly speaking, this group (of all groups) ought to take the trouble t=
o actually document operating temperatures of our units in a scientific w=
ay. After all, we are compulsive types, and prefer to pay attention to de=
tail.  Inexpensive battery operated LCD temperature monitors can be acqui=
red from shops that sell customized computer case accessories for around =
$16-$22. These come with small temperature sensors that can be mounted an=
ywhere on (or inside) a shield. Such results would be an interesting post=
 for the ambitious members in this group....=20
>
>Another point that has been brought up earlier, is to leave the unit on =
all the time, not only for temperature stability, but to avoid power surg=
es through thermally vulnerable portions of our tubes. My own practice is=
 to use a Variac to power up, with a thermal delay for B+, as described b=
y another list member.=20
>
>W. Li
>Mercer Island, WA
>_______________________________________________
> =20
>