This is a simple low-cost design consisting of straight through SO239 input --> output with ferrite toroid wound RF sensor and some filtering on the DC input. It is fitted with a rear on/off switch and an additional 50 ohm BNC sample port for connection to modulation meter, oscilloscope etc. The BNC connection can also be used to inject low power (<1vrms) signals into the meter. It can also be used as a stand-alone RF sampler/sniffer - in this mode no DC power to the unit is needed.
The counter is housed in a quality ABS case made in the UK.
The counter is useful for accurately checking radio TX frequency - connect to dummy load or antenna. The 2x RF sockets are bi-directional and can be connected either way around. Frequency is displayed when radio is keyed up into transmit (after ~1 sec delay). Works best with carrier (AM/FM), SSB will read fine but needs a steady 'whistle' / microphone input. Note - the unit is not intended to be used as a precision lab instrument.
Calibration checked and adjusted against a GPS locked reference oscillator (GPSDO) at 10Mhz (see photo), and readouts checked against my Racal Dana counter - (correlation +/-5Hz).
Tested on 160m, 80m, 40m, 20m, and 10m bands and CB frequencies (27Mhz). RF power input has been tested to 50w FM/AM which is more than enough. Do not connect to output of a linear amplifier!
The unit has also been tested on the 2m band (VHF) and does give a accurate readout at low power (below 10w). Above that level, it may give spurious readings. I do not guarantee the unit for VHF/UHF.
12V DC supply required. Can be powered from 13.8v CB power supply, car battery, or separate 12v adapter. The counter module is rated up to a maximum 15v but not recommended for prolonged use. DC power lead included.
The unit is hand-built by me, and may have minor marks and scratches from handling, therefore I am listing this item as 'used'.
The unit you see in the photos is the one you'll receive.
A short video of the unit in operation is available on my Facebook page.
The test radios / Racal counter are not included in this sale!
Postage is Royal Mail tracked 48 or collection from Darlington.
Any questions please ask.
Also available in high quality extruded aluminium case - please see other listings/enquire.
Thank you
Lake Vintage Electronics