The question was asked, so in a spare moment I
fired up the Tektronix Type 191 Constant Amplitude
Signal Generator and fed RF into the direct input
to the OHR DD-1.
Here are the frequency limits for a pure sine
wave input with voltage peak-to-peak values
and the upper frequency limit where the DD-1
display started to 'jitter'. I didn't get the
measurements down to nearest 0.5KHz on this,
so don't make or break this on these figures
alone, but they are pretty good and in the
ballpark:
Input [V p-p] Frequency at which jitter starts
100mV 22.0 MHz
150mV 31.0 MHz
200mV 34.0 MHz
250mV 36.0 MHz
300mV 38.5 MHz
500mV 47.0 MHz
1.0V 58.0 MHz
1.5V 62.0 MHz
2.0V 64.0 MHz
On page 10 of the assembly manual Dick Witzke
notes the input should be in the range of 75mV
to 1V RMS and up to 50MHz.
I use this puppy on the OHR-100 for 40M and it
works very nicely, although I'm not one that has
to have the frequency down to the last 100 Hz.
I write it down in the log book to 1KHz and that
is enough. An hour later after a QSO, noone cares
anymore.
This unit assembled using Kester 63/37 solder
cleaned with lukewarm water. :-) Can you get
CCL4 anymore? That stuff is nasty, real nasty.
Lost a friend in 1984 who used to clean computer
PC boards in a poorly ventilated area and to this
day I still believe the reason he got Luekemia
was due to this stuff. We used to use this stuff
in High School biology to terminate critters for
our required insect collection. One of the few
headaches that I have ever had in my life I got
from this stuff.
OK, I'm back to the super pixie writeup and work.
Film at 11.
dit dit
Chuck Adams K5FO CP-60 adams@sgi.com
http://reality.sgi.com/employees/adams_dallas/
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