Hello guys need help installing aChinese frequency counter from eBay to my 142 gtl any help would be appreciated.
Model:
Model:
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Cobra 142 gtl frequency counter
- Thread starter kaos513
- Start date
We've been using the six-digit PLJ-6LED version. They come with unshielded wires for both power and signal input.
You'll probably want to obtain a 7808T 3-terminal voltage regulator chip to power the counter from 8 Volts. Running it from the radio's main 13.8 Volts may overheat the counter's on-board regulator.
Tap off of the radio's test point TP1 for the counter's signal input. A 100 ohm resistor between TP1 and your counter input will prevent it from loading down the radio's internal signal level. If the signal lead isn't fairly short you may need to use shielded wire. The lower the capacitance per foot this wire has, the better.
I have no idea what's involved with setting a display offset. If it's the same as the 6-digit, no problem. Just haven't tried the 8-digit yet. Couldn't come up with a good reason.
Besides, putting them into an analog VFO would be a waste of the extra two digits, considering the way the frequency will drift.
73
You'll probably want to obtain a 7808T 3-terminal voltage regulator chip to power the counter from 8 Volts. Running it from the radio's main 13.8 Volts may overheat the counter's on-board regulator.
Tap off of the radio's test point TP1 for the counter's signal input. A 100 ohm resistor between TP1 and your counter input will prevent it from loading down the radio's internal signal level. If the signal lead isn't fairly short you may need to use shielded wire. The lower the capacitance per foot this wire has, the better.
I have no idea what's involved with setting a display offset. If it's the same as the 6-digit, no problem. Just haven't tried the 8-digit yet. Couldn't come up with a good reason.
Besides, putting them into an analog VFO would be a waste of the extra two digits, considering the way the frequency will drift.
73
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Kaos was indicating an 8 digit RF sampling frequency counter (.1-1000 MHz) rather than a PLL/VCO/VFO sampling one (with adder or subtractor circuit to show the radio's apparent frequency).
The above mentioned frequency counter has a PIC16F648A microcontroller, and if direct sampling the PLL/VCO frequency (34 MHz), would have to be reprogrammed to subtract the carrier offset (7.8 + or - 2.5 KHz for mode) from the VCO frequency to display 26/27 MHz.
And also, would need an enclosure to mount it in, or where to put the display?
Oops, I didn't read the fine print on this unit, it has programmable adjustable offset.
The above mentioned frequency counter has a PIC16F648A microcontroller, and if direct sampling the PLL/VCO frequency (34 MHz), would have to be reprogrammed to subtract the carrier offset (7.8 + or - 2.5 KHz for mode) from the VCO frequency to display 26/27 MHz.
And also, would need an enclosure to mount it in, or where to put the display?
Oops, I didn't read the fine print on this unit, it has programmable adjustable offset.
Last edited:
Thanks will try it tonightWe've been using the six-digit PLJ-6LED version. They come with unshielded wires for both power and signal input.
You'll probably want to obtain a 7808T 3-terminal voltage regulator chip to power the counter from 8 Volts. Running it from the radio's main 13.8 Volts may overheat the counter's on-board regulator.
Tap off of the radio's test point TP1 for the counter's signal input. A 100 ohm resistor between TP1 and your counter input will prevent it from loading down the radio's internal signal level. If the signal lead isn't fairly short you may need to use shielded wire. The lower the capacitance per foot this wire has, the better.
I have no idea what's involved with setting a display offset. If it's the same as the 6-digit, no problem. Just haven't tried the 8-digit yet. Couldn't come up with a good reason.
Besides, putting them into an analog VFO would be a waste of the extra two digits, considering the way the frequency will drift.
73