[Elecraft] XV50 heating report.

[Don Wilhelm]

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