#466 VC3165
All about the Victor VC3165 frequency counter.
Notes
I’ve been using the Victor VC3165 frequency counter for some time, and it’s proven a very reliable bit of kit. I’ve used it mainly for signals from DC to a few hundred MHz, though it’s range does extend to 2.4GHz.
I purchased mine from Instruments World Store on aliexpress.
What follows is an overview of the operation and a bit of a look at the internals of the unit.
Enclosure
The instrument uses a standard enclosure. Front and rear panels are well layed out, although the gate control knob below the channel inputs can be inconvenient to get to with leads attached.
The unit I received had some button labels only in Chinese, so I’ve stuck on my own labels in English. A manual is available electronically in English which helped!
A look inside the case:
Function and Counter Modes
The function key selects between 3 modes. The input channel used depends on the mode:
| Function | Coupling | Freq. Range | Gate time min | Gate time max. | Channel |
|---|---|---|---|---|---|
| 1 | AC | 1GHz-2.4GHz | 1kHz | 100Hz | B |
| 1 | AC | 50MHz-1GHz | 1kHz | 10Hz | B |
| 2 | AC | 2MHz-50MHz | 1kHz | 10Hz | A |
| 3 | AC | 100Hz-2MHz | 10Hz | 0.1Hz | A |
| 3 | DC | 0.01Hz-100Hz | 0.001Hz | 0.001Hz | A |
AC/DC Switch
In mode 3, the AC/DC switch selects between low frequency AC signals and verl low frequncy DC signals (DC measurement is required for anything under 100Hz).
Gate Control
The gate control knob adjusts the gate time (range depends on the mode). This can be important for correctly locking on to a signal with the required accuracy.
- short gate time: faster measurement, but resolution is lower
- longer gate time: slower measurement, but higher resolution
Power Supply
The VC3165 has a low noise linear power supply. Mains power is stepped-down with a transformer with primary windings switchable for 220V/110V.
The approximately 9V AC is regulated to 5V with a KA78R05 low-dropout voltage regulator.
Main Board
I haven’t traced out the circuit, but interesting to note that it appears to be a version of a conventional CMOS counter design, with an AT89C4051 microprocessor in control.
The main clock source is in a shielded housing. This may even be a temperature-controlled “crystal oven” but I’m not sure. There’s been some thought put to providing good shielding:
- top cover is lined with a ground plane
- each input front end circuit is in it’s own shielded housing
IC listing:
- AT89C4051 CMOS 8-bit microcontroller with 4KB of flash
- 74F74PC dual D positive edge triggered flip-flop, asynchronous preset and clear
- 74LS373N octal transparent latch
- 74HC393N dual 4-bit binary counter
- 74HC153N dual 4-line to 1-line data selector/multiplexer, non-inverting outputs
- 7555 CMOS 555 timer
- LM393 Dual Differential Comparator
- KA78R05 5V low-dropout voltage regulator
The front display board has a Microchip CF775-04/P (I think a PIC variant) specialised for display control.
Credits and References
- 110V/220V New Style Top Quality 0.01Hz - 2.4GHz Precision Frequency Meter Frequency Counter VC3165 - from Instruments World Store on aliexpress