Modifying a 1.2GHz Video Receiver

I have the impression that the only the box will be useful. The 1.2 GHz is far away from FM radio that operates between 88 and 108 Mhz. That potmeter will not provide the miracle I guess.

Would there be any way to modify the tuner box? It can be connected to a normal TV areal aswell.

You have a video and audio output available. If you have the voltages required, you might be able to use a TV HF tuner next to it and start from there. It has roughly the same appearance. The inside of the box shows a lot of " Lecher line plumbing" These parts are quantified by size for specific frequencies.

There is not a lot of choice between "popular adopted" HF connectors. That is why they show up on various applications.

But remember TV is

1. HF reception (tuner or channel dial)

2. MF (mid- frequency) detection and separation + standard adaptation

3. Separation Video and audio.

Unless you have a complete TV lab instrumentarium, placing the points on the i's will be a challenge.

Oh well, nothing is ever that simple. I thought I had myself a nice radio scanner. I also noticed that connecting it to the house TV areal makes the signal sent from the transmitter worse. Even when I take the transmitter outside. How can a bigger professionally fitted areal make a signal worse than that recieved with the tiny one on the back of the unit?

Antennas and transmitter/receivers are generally matched to their frequency- range.

The physical antenna length and the wave length have a common relationship.

The wrong antenna size will automatically reduce the reception quality or quantity or even block the signal.

So a higher frequency would mean a smaller areal?

Indeed.

You might be interested in an antenna calculator.

Go to Crompton.com antenne length or google it.

For standard antennas Lambda/2 or Lambda/4 is used a lot as reference. Lambda is the wavelength.

(Dish antennas may cut to Lambda/10)

Is someone else home?

What is "not a prayer" and specific IF please? Thanks

I gave a GA for not a prayer which was Anonymous Hero's way of saying that your project as stated is doomed to failure. Even if you could detune the local oscillator far enough to reach the standard FM band (88MHz - 108MHz) the multiple IFs (intermediate frequency tuned circuits) would make the amplifier of little to no use. If instead, you tried to detune the local oscillator to a frequency close to what it is already operating, it may give you some interesting results. I am not sure just what those would be. If your unit is working fine and has a purpose that you still maintain, I would try to keep it just as is as it has been tuned to a specific application. If you have no need for it and are willing to detune it to the point that it will not work for its intended use, then go ahead. It will make a neat toy until you tire of it and its lack of useful purpose. Chances are that once you detune it, you may have a hard time retuning it. Just my honest opinion.

Well said. Add to that you will need some sort of RF test set or RF tools to perform the alignment (and the expertise to use them).

The IF stands for Intermediate Frequency. In a superheterodyne receiver they are the internal stages that create beat frequencies for the process of demodulation.

For example, most receivers for FM use an IF frequency of 455 kHz.

Definition of IF

Thank you, same as we call "midden (middle) frequency - IF sounds more to the point.

The varicap used for tuning has a limited withstanding voltage so don't expect much wider range. Also IF of a Ghz tuner could be quite high and even trying to change it requires filter topic knowledge and special equipment. Not good odds for this project. S.M

Oh, everything is so complicated. This reciever came with a wireless camera kit and the camera got broken due to me connecting it to a battery with the wrong polarity. The little video transmitter inside the camera still works so I took the camera apart and if I connect the transmitter to a battery and a composite video source, it transmits video. 10mw i think it is. The transmitter takes a current of 25 milliamps.

Provided you haven't messed with it yet, you can still get another camera and use it. De-tune it, then maybe throw it away. As Anonymous Hero says, you will need test set, tools, etc. to re-tune the set, not to mention a manual or schematic of the device and knowledge of the IF tuned circuits. If you haven't messed it up, it can still be useful in a homemade security system. Hook up another cheap camera to it and transmit the signal to a hidden remote VCR unit. With this kind of setup, criminals are either caught on tape (for later prosecution) or they give some consideration to just passing your property by of they can see the camera units placed around.

I havent done anything with the tuner at all. I added a small nut and bolt to a mosfet inside to transfer heat to the casing because when the receiver gets connected to a 12v battery, a lot of heat comes from the mosfet.