Posted by
Johnny Siu on
Jun 15, 2010; 1:27am
URL: http://elecraft.85.s1.nabble.com/XV50-heating-report-tp5178072p5180051.html
Hello Don,
Thanks a lot for your effort and the informative report.
I agree with you that the PA module should survive under the test condition. However, I am not sure whether such a continous high working temparture will eventually shorten the working life of other components.
I trust Elecraft will be happy with your effort as well. Your work has greatly reduced Elecraft's work load though they should officially confirm that the XV transverters are perfectly ok to work under their advertised rated output (even too hot to be touched).
As suggested by some of the Elecrafters, a retro kit with internal fan similar to XV432 may be a solution to address this issue.
Through years in this reflector, I very much appreciate your contribution in solving my elecrafters problem.
TNX & 73
Johnny VR2XMC
----- 郵件原件 ----
寄件人﹕ Don Wilhelm <
[hidden email]>
收件人﹕ Elecraft <
[hidden email]>
傳送日期﹕ 2010/6/15 (二) 12:04:57 AM
主題： [Elecraft] XV50 heating report.
I had promised several here in the Elecraft reflector some temperature
rise data for the XV50 a week ago, but had to delay it due to a failure.
Here it is now.
Conditions: XV50 plugged for 5 watts drive = 20 watts out (attenuators
were dissipating heat).
This is a new XV50 with vent holes in both the bottom
and top panels.
Operation tested at 10 watts - keydown 1 minute, idle
for one minute (simulated FM
operation) CW was actually the mode used.
Ambient temperature 23 deg/C.
Measurement made with temperature probe of Fluke 179
mounted below heat spreader -
The probe end was secured to the bottom panel with a
solder lug temporarily placed under a heat
spreader mounting screw.
Interval# Start temp End Temp
1 23 47.1
2 45.0 51.6
3 50.1 55.8
4 52.9 59.0
5 55.4 60.9
6 59.0 63.3
7 61.0 65.0
8 63.0 68.8
9 65.0 70.4
10 66.7 71,2
11 68.3 73.0
After a 1 minute cool-down, a 2 minute keydown was measured
69.0 80.5
The time for the temperature to drop from 81 deg/C to 60 deg/C was
measured at 4 minutes.
The receive sensitivity was measured at ambient and at 60 deg/C - the
difference was less than 2 dB which is within the range of measurement
error. Spectrogram was used for this sensitivity measurement with a
-140 dBm signal injected from an HP8640 signal generator. The
difference between the signal amplitude and the receiver noise floor at
the filter passband peak was measured to determine any change in
sensitivity.
Whether this data indicates a problem or not is not for me to determine
- the XV50 has no temperature rise specified. Yes, it does get hot with
the 1 minute on, 1 minute off cycling. Too hot to comfortably touch.
Whether this cycling time is typical of your operation is also not for
me to determine. A greater non-transmit time will allow the XV50 to
cool between transmit cycles and limit the temperature rise.
Mitsubishi specs the *operation* case temperature range to be -31 to 110
deg/C which is higher than usual, but in their datasheet notes at the
bottom seems to recommend that the temperature be kept below 60 deg/C,
so even that data is not consistent. You will have to draw your own
conclusions about the differences in the datasheet.
73,
Don W3FPR
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