Steve -
I think 30 minutes is a reasonable 'warm-up' time. IF the radio is in a controlled environment.!!
Take one out of the garage in winter and plug it in, it's gonna take considerably longer before
everything reaches equilibrium. You have some sizable chunks of iron and steel in there that can
absorb quite a bit of heat. From 60 degrees to a 'nominal' 75 degree ambient on top of normal
internal heating would take a while, perhaps an hour?!? :-)
Plus as Evan said there will be a delta from transmitting as well. A fan makes a BIG difference in
this if you are into long transmissions or TTY, etc. This is one reason why the TR-7 fan is used to
exhaust hot air from the PA right out the back rather than blow it in all over the radio, including
the PTO, with each transmission.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Steve Wedge wrote:
I always assumed it was a 30 minute warmup, because I seem to remember the alignment procedures
spec 30 minutes warmup before doing an alignment.
Steve Wedge, W1ES/4
"I can't complain, but sometimes I still do."
- Joe Walsh
If the above message appears, it came from Steve's Son of Laptop!
----- Original Message ----- From: "Eddy Swynar" <deswy...@xplornet.ca>
To: <drakelist@zerobeat.net>
Sent: Friday, November 25, 2011 2:32 PM
Subject: [Drakelist] T-4X Stability
Hi All,
The manual for my T-4X states that stability is "LESS THAN 100 CYCLES AFTER WARM-UP". My question
is simply this: how long, exactly, is an accepted period of "....warm-up"...?
After all of the hoops that I've jumped through in stabilizing the PTO in my rig (re-buiding it
almost, actually!), I decided this morning to actually measure its drift. I used my ICOM 751A
transceiver (in general coverage mode) as the frequency "umpire", and tuned it directly to the
Drake PTO's output frequency of 5454.0-KHz. Both rigs were in the basement overnight, where the
ambient room temperature was 59F. I measured the frequency a total of SIX times, i.e. (1)
immediately at the start of the test, (2) 3 minutes into the test, (3) 15 minutes into the test,
(4) 30 minutes into the test, (5) 1 hour into the test, and finally (6) two hours into the test...
Here are my results:
(1) 5454.0-KHz (cold start);
(2) 5454.0-KHz (unchanged from cold start);
(3) 5453.5-KHz (downward drift of 500-Hz from cold start);
(4) 5453.0 KHz (downward drift of 1-KHz from cold start);
(5) 5452.8-KHz (downward drift of 1.2-KHz from cold start), and,
(6) 5452.8-KHz (unchanged).
So---it looks like the rascal that I have here stabilizes after a good hour of steady warm-up,
which leads me to suspect that maybe "warm-up" to the writer of the manual was, in fact, just
that, i.e. one hour...?
No matter, it was a most interesting exercise---and I sure would be curious if my rig's
performance might match that of some of the other T-4Xs that are out there...although I dare say,
probably not everyone has as thick a hide as I do in being able to withstand a 59F ambient room
temperature...! Hi Hi.
~73~ de Eddy VE3CUI - VE3XZ
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