HP-310A
Wave Analyzer
I found this HP-310 at W.J Ford Surplus in Canada. I am currently
using it as a VLF / LF Receiver.
I did this
picture of the 310 in black and white in keeping with the 1963 design
date of the unit!
The HP-310 is an all
transistor design that dates back to 1963. The unit I have works
beautifully. This is a true example of fine design. I checked the
unit out when I got it and it was still well within factory
calibration! For 1963, this is a very sophisticated design. It is an
upconverting superhet design (3 MHz IF), with a frequency range of
1000 Hz to 1.5 MHz. The signal level is rated at 10 uV to 100 Volts
input (selected by two range switches). The wave analyzer concept was
developed at HP to test voice telecommunications circuits. It may
also be used as a low frequency scalar network analyzer (it has a
built in tracking source). Dr. Barney Oliver (Chief Engineer @ HP)
designed a linear, air variable tuning capacitor for the 310 (and
it's predecessor the 302). This allowed for the mechanical tuning
counter seen (since the tuned frequency was a linear function of the
capacitors rotation) . HP also produced a motor driven "tuner" that
could be attached to the main tuning knob on the front of the
analyzer. Then, by using the recorder output connected to an XY
plotter (which HP also produced), a linear input versus frequency
plot could be produced. This was truly a automatic network analyzer,
produced in 1963! Another application cited by HP was the analysis of
low frequency harmonic distortion products.
The meter on the
front reads out absolute dB or volts of the tuned signal. A relative
mode may also be selected allowing the receiver to be set to a
fundamental signal and relative measurements made on
harmonics.
A January, 1963 HP
Journal article introduced the instrument.
The design is current
by todays standards. The narrow IF bandwidths were produced by
quadrature converting the signal to IQ channels at baseband where
narrow frequency active filters could be built giving bandwidths of
200, 1000 and 3000 Hz. The IF was then translated back to 3 MHz and
added together to remove the quadrature component. This method dates
back to the late 50's (Weaver, Proc. of the IRE, 1958) for SSB
generation. The method is still in use today in the DSP world by
Harris Semiconductor. Their digital HSP50016 Digital Downconverter
uses exactly the same principal to get very narrow digital IF
bandwidths!
The instrument used
HP's second generation "Glow FET" chassis. The inside of the 310
looks empty since it was built with transistors. All of the circuits
are built on plug in cards and in separate shielded
compartments.
All told, the
transistor count in the instrument is just 60 devices. Using OPAMP's
today the transistor count would be in the thousands! That's
progress? The 310 is designed with the usual 60's selection of
Germanium and Silicon transistors. If any of the Germanium devices
fail, I'll have to rebias the circuitry for Silicon
replacements.
I have found the
instrument to be just great at receiving WWVB with my 4 foot loop. It
has very good intermodulation performance for a "wide band" front
end, as it rejects all of the much stronger LORAN signals less than
an octave away in frequency. It is also very tolerant of the
fluorescent lighting in my workshop (It's better than my Sony
2010).
The 310 has provision
for AM, USB and LSB reception by the twist of a knob. A front panel
BNC easily drives headphones for listening. I have received AM
broadcast stations in Canada, Texas, and a low power AM station in
Boise Idaho (from my northern California location). The 310 easily
tunes around hetrodynes on crowded AM channels. The only deficiency
it has as a receiver is relatively flat audio quality. I intend to
improve that, with the inclusion of a 20 transistor audio amplifier
IC (well, that is progress, I guess).
HP's first wave
analyzer was the 302 designed in 1959, also a transistorized design.
Then came the 310. The 312 came along next and featured a maximum
frequency of 18 MHz. The 312 also sported a digital frequency
display. The 312 looks very much like an upgraded 310 (same chassis).
Next came the digital 3581 family. This analyzer dropped back to 50
kHz maximum frequency, but was much smaller. The last in the line was
the 3586 produced in 1980. The 3586 is fully synthesized and covered
50 Hz to 32 MHz. Digital techniques applied to Spectrum Analyzers
ended the need for Wave Analyzers and now cover the market that was
once held by these instruments.
HP310
SPECIFICATIONS:
Frequency
range.................................... 1 - 1500 kHz
Tuning
Accuracy.................................... 1% +/- 300 Hz
Frequency
Calibrator............................. 100 kHz (even and odd
harmonics, up the band)*
Selectivity...............................................
200, 1000 and 3000 Hz BW, 3dB
Shape
Factor.......................................... 2:1 (to -25 dB
down)**
IF Ringing
Immunity.................................. Very good (Butterworth
response)**
Voltage
Range........................................ 10 uV to 100 V full
scale (140 dB)
Voltage
Accuracy................................... 6% (on the meter)
Dynamic
Range...................................... >70 dB
Input
Resistance..................................... 10, 30 and 100 K ohms
(Depends on full scale input range)
Power...................................................
110/230 VAC at 16 Watts
Weight..................................................
44 pounds (it's that darn chassis!)
Front Panel
Controls:
Max Voltage Range,
Relative or Absolute, Range (in dB), Bandwidth, Mode (AFC, Normal,
BFO, USB, LSB and AM). Frequency (Fine and Coarse), Zero Set, and
Tracking (also AM Output) Amplitude.
The unit also
incorporated a "sweeping" AFC circuit to keep the signal locked in on
narrow bandwidths.
* The calibrator was
supposed to be a 60/40% duty cycle square wave, my unit is closer to
50% duty cycle, so I only get odd harmonics of the calibrator (I need
to fix this).
** HP did not
originally specify these things, these are my "Supplemental
Specifications".
Modified -
7Jan02