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| fourfathom:
I've got a bunch of homebrew test gear. The photo shows a 10W RF attenuator, a resistive 4-way splitter, and a Time Interval Counter (TIC) of my own design and build. The TIC has this inside: * A 100MHz internal clock (a PLL inside a gate-array), which can be locked to either an internal 10MHz TCXO, or an external reference (such as the Bodnar GPSDO I usually use). * Four inputs, AC or DC coupled, 50 Ohm or 10 Meg termination, >100 MHz input response. Any of the four inputs can be used as the external reference clock * Selectable divide-by-ten prescaler, settable 32-bit divider for each of the four measurement channels, Rising/falling edge selection * Timestamp capture for each measurement channel, 10 ns resolution. Event / Interval / Period / Frequency calculation and reporting * An internal NCO / mixer / filter which provides high-resolution measurements of narrowband high-frequency inputs (example: < 10 milliHz resolution of a 10 MHz input at a 10 Hz measurement rate) * OLED display (the photo shows the screensaver, a scrolling sinewave to reduce OLED pixel burn) * USB "serial port" control and reporting interface to external programs. About 50 measurements per second max reporting rate (serial port limitations) The chart photo shows a frequency vs temperature measurement I made this morning, testing the TCXO in a ham transceiver. The chart shows a frequency of about 100 Hz; this is actually the difference between the 25 MHz TCXO and the internal NCO. This shows that the TCXO frequency is varying by about 3Hz. I used a modified "Reptile Incubator" with a homebrew controller as a temperature chamber. Notice the frequency "retrace" as the temperature cycles up and down. I've got lots more homebrew gear, but I had these photos handy. |
| paul@yahrprobert.com:
--- Quote ---GPIB / USB adapter. --- End quote --- Very nice GPIB adapter. What design is that? It looks similar to the Galvant design. |
| dobsonr741:
DDS function generator based on AD9833, VCA822, TLV5618, Raspberry Pi Pico. Controllable by SCPI and a UI, has a bonus +/-3V programmable voltage source with 12 bit resolution. Attenuator down to -60dB. |
| MrYakimovYA:
8 channel thermometer. DS18B20 as a sensor. Raspberry Pi Pico (clone) inside. |
| MrYakimovYA:
High Resistance Standard. For calibration of a picoammeter that I'm developing. Upper red banana jack was replaced with BNC later. |
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