I like warming up the counter for a while if not possessing an oven. Can't
remember if a Fluke 1911A has one, or not.
Steve Wedge, W1ES/4
I swear by my life, and my love of it, that I will never live for the sake
of another man, nor ask another man to live for mine.
-Ayn Rand.
All my computers have my signature with various pearls of wisdom appended
thereto.
--------------------------------------------------
From: "Garey Barrell" <[email protected]>
Sent: Friday, November 25, 2011 10:07 PM
To: <[email protected]>
Cc: <[email protected]>
Subject: Re: [Drakelist] T-4X Stability
Curt -
Excellent point. I missed the 'standard' in the first read of Eddy's
message. I always use an 'ovenized' counter and just .... well, you
know.. :-)
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>
Curt Nixon wrote:
Not sure anyone asked this, and I didn't see it in your initial post, but
was the 751A already warmed up when you tested the drake?
What is the frequency reference in the 751A?
I recently used a 751 which is essentially the same frequency determining
set-up for a freq measurement test and I can tell you, it isn't all that
stable either...and, it goes up and down with small temperature
differences over a span of only several minutes. Even when it had been
running in Rx only for over 24 hours.
So..keep in mind that the data you recorded is the net difference from a
moving reference.
After warm-up, I'm not so sure that the 751A is any better than the
Drake.
They are a lot better if they have the TCXO module added, but I didn't
see that mentioned.
Anyway, just curious what the reference conditions were.
Thanks
Curt
KU8L
On 11/25/2011 5:57 PM, Garey Barrell wrote:
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" <[email protected]>
To: <[email protected]>
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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