Frequency counter easy internal hookup info needed

[Techno1]

Is there a cheap frequency counter out there that will work on all the cobra president uniden radios that use the mb8719 and mb8734 pll.

Looking to wire one internally in the radio and have it sit on top. Of course a cable will be needed to connect inside and then also power the counter.

Need it to read the channel on radio in receive and transmit mode.
I know there will have to be an offset for the freq counter. I do see the ones on ebay from china will one of these work.
Are there any directions out to install one of these?

148gtl
2000gtl
washington
radioshack490
grant and other such radios.

thanks for any help

 

[nomadradio]

A frequency counter that shows a straight display of the input frequency will only work if it's tapped into the radio's antenna output, and only in AM transmit with a steady dead carrier. As soon as you modulate, the reading will fluctuate.

A frequency display, tapped into the radio's internal frequency-control circuits will read all the time, receive and transmit. To do this, it has to have the arithmetic built in so it can add or subtract the so-called "offset" between the channel frequency and the radio's internal synthesizer frequency.

Here's an example of a popular item found on fleabay, the "SanJian" brand model PLJ-6LED frequency display.

https://www.ebay.com/itm/3352210422...d=link&campid=5336136228&toolid=20001&mkevt=1

It has two pushbuttons that control a setup program. You can put the correct offset for your radio into it, along with proper arithemetic for high-side injection around 35 MHz like the radios listed above, or low-side like Galaxy/Connex and other radios.

Just a couple of gotchas. No enclosure. There was a guy selling a laser-cut plastic case a few years ago to fit these, but I haven't seen his stuff offered for a while. You need to install a 8-Volt regulator chip in the radio to power this thing. It's meant for a low power supply voltage. Simply hooking it straight to a solid-state radio's 13.8-Volt DC source can overheat the counter's voltage regulator chip.

And you have only one offset to work with. In the models you mentioned, this offset number changes slightly from AM to LSB to USB. The PLJ6 will read correctly for only one mode, and show an error a few kHz on the other two.

An external box means the shielded cable carrying the radio's internal synthesizer frequency out to the counter may be long enough to cut down the signal level too low for a stable display. The longer the cable, the bigger this risk. And mounting it inside the radio keeps this part of the hookup short.

Never have seen a detailed step-by-step for doing this to the radios you mentioned. For us it's always been a figure-it-out-as-you-go proposition.

73

 

[Techno1]

Nomadradio

thanks for the reply and info.

I figured that a long cable would be a problem.

Im just working on a new channel kit a microchip mod that will expand the 8719 and 8734 plls radios from 26.495 to 28.325. Teststing on a Radio Shack trc490 same as a Washington at this time.
Only tuning need is equal power and receive no frequency tuning as its a pll mod with a pic chip.
Kit will even go higher 29mhz but radio will not broadband for all the channels and thought building all this is a small box with a freq counter would be good not needing a cheat sheet for channels Just info on the switches to give all the extra channels.

the kit is pic controlled and no crystals.

Remove either the 8734 or 8719 pll stow away not needed, install a socket plug in module and mount switches on radio.
Or plug cable into the socket and mount small box that has the switches on top of radio. box is very small and will have a ribbon cable out the back that will connect inside of radio. All channels controlled by a 3 pos rotary switch and 2 toggles for a 10kc missed channels.

So if i could incorporate a freq counter would be great almost like the old Redco digiscan just no scan the mod will be fixed channels/bands.

I have one circuit working now and will be real easy to install.
You can always unplug cable and reinstall the original pll and radio back to stock.

Guess Ill have to think about the freq counter and just make a good road map.

thanks again