Using a Frequency Counter with a Zenith Trans-Oceanic?

[vortalexfan]

Hello everyone, I had aquired a while back a Heath-Zenith (Heath Kit) Frequency Counter to use with an older Radio City Products Signal Generator (which I have since replaced with a Hewlett-Packard Signal Generator, that has a built-in Frequency Counter.)

So I had the thought that maybe I could use my Frequency Counter with my Zenith Trans-Oceanic Radio to figure out where I'm at on the tuning dial (especially when tuning in the SW Bandspread) but I have no idea where I would hook the frequency counter up to the radio to track the tuner, I had tried hooking it up to the input on the tuning condensor but that didn't do much good as it just showed nothing but gobledygook on the frequency counter (the "frequencies" that were showing up on the frequency counter were nowhere near what the bandspread was supposed to be tuning in.)

Anyone have any experience with attempting something like this and know where I should hook the frequency counter into the radio to get it to show where the tuner is tracking?

Any help would be appreciated.

The Zenith Trans-Oceanic Model in Question is a G500 from 1950 (the first miniature tube model.)

[kf4rca]

You would connect to the oscillator output. BUT, that is going to read 455 khz. high (or low depending on design).
A while ago there were kits available that had the offset built in. Here's a link for more info:
https://www.instructables.com/Add-a-...nications-Rec/

[vortalexfan]

Originally Posted by kf4rca

You would connect to the oscillator output. BUT, that is going to read 455 khz. high (or low depending on design).
A while ago there were kits available that had the offset built in. Here's a link for more info:
https://www.instructables.com/Add-a-...nications-Rec/

So I'm guessing its a very similar setup to how a signal generator works?

Because basically isn't a Signal Generator just a tuner minus the front end and amplifier stages?

So is there any way to use an already built Frequency Counter to do this function, or do I have to use the units that the person in the link used, like is there anyway to make that offset circuitry and use it with an already pre-existing (built) Frequency Counter?

[old_tv_nut]

I would say it's a minor nuisance to do the subtraction or addition of 455 kHz, so just go for it.

A signal generator is equivalent to the local oscillator part of the tuner. The tuner also contains (at least) a "mixer" stage. The mixer multiplies the oscillator wave with the signal wave, converting the signal wave to IF frequency. In the usual AM radio, the local oscillator is tuned by the dial to a frequency that is above the desired signal frequency by 455 kHz, so the signal is converted to 455 kHz range for the IF to amplify.

For a very thorough discussion when you have the time, see wikipedia: https://en.wikipedia.org/wiki/Superh...er%20frequency.

[kf4rca]

Found this on Ebay:
https://www.ebay.com/itm/38362912255...Bk9SR7at5s_aYA

[vortalexfan]

Originally Posted by old_tv_nut

I would say it's a minor nuisance to do the subtraction or addition of 455 kHz, so just go for it.

A signal generator is equivalent to the local oscillator part of the tuner. The tuner also contains (at least) a "mixer" stage. The mixer multiplies the oscillator wave with the signal wave, converting the signal wave to IF frequency. In the usual AM radio, the local oscillator is tuned by the dial to a frequency that is above the desired signal frequency by 455 kHz, so the signal is converted to 455 kHz range for the IF to amplify.

For a very thorough discussion when you have the time, see wikipedia: https://en.wikipedia.org/wiki/Superh...er%20frequency.

I have a Zenith Royal 2000-1 that has a tuner output RCA jack on the back so that one can make an AM only radio into and AM/FM Radio (like my Magnavox Berkley for example that has an FM Tuner hookup on the back) and I was wondering if that would be a way to hook into a frequency counter for a radio?

[Electronic M]

Originally Posted by vortalexfan

I have a Zenith Royal 2000-1 that has a tuner output RCA jack on the back so that one can make an AM only radio into and AM/FM Radio (like my Magnavox Berkley for example that has an FM Tuner hookup on the back) and I was wondering if that would be a way to hook into a frequency counter for a radio?

Nope. Unless you want to count the instantaneous frequency of the musical notes of your songs or maybe some tiny IF frequency leakage...The audio output is not an Osc test point...It should be obvious to you.

[vortalexfan]

Originally Posted by Electronic M

Nope. Unless you want to count the instantaneous frequency of the musical notes of your songs or maybe some tiny IF frequency leakage...The audio output is not an Osc test point...It should be obvious to you.

OK, thanks for the heads up.

[old_tv_nut]

Originally Posted by vortalexfan

I have a Zenith Royal 2000-1 that has a tuner output RCA jack on the back so that one can make an AM only radio into and AM/FM Radio (like my Magnavox Berkley for example that has an FM Tuner hookup on the back) and I was wondering if that would be a way to hook into a frequency counter for a radio?

I take "tuner output" to mean this is either amplified RF or IF from the mixer. It has to be one or the other if you are going to send it to an FM detector.
Whatever it is, it's not the constant high level local oscillator output. You need to measure the local oscillator frequency and subtract 455 kHz from that to calculate the station frequency you are tuned to.

[Electronic M]

Originally Posted by old_tv_nut

I take "tuner output" to mean this is either amplified RF or IF from the mixer. It has to be one or the other if you are going to send it to an FM detector.
Whatever it is, it's not the constant high level local oscillator output. You need to measure the local oscillator frequency and subtract 455 kHz from that to calculate the station frequency you are tuned to.

I own the same model of radio and can assure you that the RCA type TUNER jack is a line level audio output for an external amplifier. The inside of the back flap even has the schematic printed on it...I took a picture and used the pencil to point out the jack at the first audio stage.

It's possible if there's no low pass filter to remove the FM MPX stereo ultrasonic carriers you MIGHT be able to plug an accessory FM MPX decoder from a early 60s console, connect it and get FM stereo demodulation, but I haven't tried it or looked for said filter.

What's interesting is it can function as an audio input too. I've been able to tune to a silent channel then back feed the tuner jack through an adapter on the headphone jack on my phone and use my Zenith as an amplified speaker for my phone (it's the secret behind how I played a specific piece of music on that radio in a YouTube video).

[vortalexfan]

Originally Posted by Electronic M

I own the same model of radio and can assure you that the RCA type TUNER jack is a line level audio output for an external amplifier. The inside of the back flap even has the schematic printed on it...I took a picture and used the pencil to point out the jack at the first audio stage.

It's possible if there's no low pass filter to remove the FM MPX stereo ultrasonic carriers you MIGHT be able to plug an accessory FM MPX decoder from a early 60s console, connect it and get FM stereo demodulation, but I haven't tried it or looked for said filter.

What's interesting is it can function as an audio input too. I've been able to tune to a silent channel then back feed the tuner jack through an adapter on the headphone jack on my phone and use my Zenith as an amplified speaker for my phone (it's the secret behind how I played a specific piece of music on that radio in a YouTube video).

OK, I wasn't sure, because I know some of the early add-on tuners like old Pilot FM Tuner from the late 1940s worked where it wasn't necessarily a line-level output that it was outputting to the radio it was being connected to.

[kf4rca]

They sure did make a lot of them.
What you could do is add a digital display, an S meter and a BFO and you would be all set to listen to the pirates on 6925 on Friday and Saturday nites!
You certainly would have enough space in the bottom where the batteries used to sit.