"Floyd Sense" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Nothing to disagree with there! I was going through the list archives the
other day looking for info on the fan, and ran across a couple of
recommendations to mount the fan so that the airflow was in, instead of out.
One of the proponents of that approach explained that the reason was that
the fan "blows more air out than it sucks in". Had he not made that
statement, I might have thought that there was some merit to the argument!
Thus far, I don't notice any drift other than during the brief warmup
period. I always get a charge out of reading the articles that talk about
how the TR7 isn't suitable for digital modes without some sort of active
compensation to stabilize the PTO. I spent many years operating RTTY with
gear that doesn't come close to the TR7 stability and can't say that I ever
noticed the difficulties from drift.
73, Floyd - K8AC
----- Original Message -----
From: "Garey Barrell" <[EMAIL PROTECTED]>
To: "Floyd Sense" <[EMAIL PROTECTED]>
Cc: "drake" <[email protected]>
Sent: Monday, November 21, 2005 10:36 AM
Subject: Re: [drakelist] TR7 fan recommendations
This comes up every once in a while....
The fan on the TR-7 should always be mounted to blow air OUT. A piece of
electronic equipment that is DESIGNED to be fan cooled has a cooling
_SYSTEM_. The TR-7 system is designed for the air to be pulled in
through the slots in the top and bottom of the cabinet and blown OUT via
the fan. Reversing this flow does not cool the entire transceiver as
effectively. As for the PTO temperature, the absolute temperature is not
particularly important, rather the change in temperature as the heatsink
heats and cools with transmissions. Blowing air IN forces the heated air
from the heatsink past the PTO area, causing the PTO temperature to
fluctuate. The dial lamp that some cite as a source of PTO drift is
actually a constant heat source that helps to stabilize the PTO area at a
slightly higher temp. There IS a "warmup" time for the TR-7 for this
temperature to stabilize.
73, Garey - K4OAH
Atlanta
Drake C-Line Service Manual
<http://www.k4oah.com>
Floyd Sense wrote:
"Floyd Sense" <[EMAIL PROTECTED]> made an utterance to the drakelist
gang
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I have a set of temperature probes and will take some readings near the
PTO with the fan blowing in and out to see what happens to the
temperature. Hard to believe that mounting the fan to blow in, rather
than out, would result in less PTO temperature rise.
73, Floyd - K8AC
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