VHF low-band TV transmitter circuits

[neazoi]

Hi, for educational purposes, I would like to study circuits and antennas of VHF low-band transmitters. However the information on the internet is pretty limited on that, unless I am not searching on the right places.
Any ideas of such circuits?
Thanks

 

[BigBoss]

What would you know ??

 

[Epontes]

I think I got what he mean.. happen the same with me..
I would like to get more information about everything about RF transmition..
For example.. how can I use a oscilloscope to measure the signal comes from a transceiver ?
let me explain you, I’m aircraft mechanic, and I need to know if the vhf transmitter is working.. one way to find it is use oscilloscope, of course, but how i use it with out damage?
thanks

 

[neazoi]

I think I got what he mean.. happen the same with me..
I would like to get more information about everything about RF transmition..
For example.. how can I use a oscilloscope to measure the signal comes from a transceiver ?
let me explain you, I’m aircraft mechanic, and I need to know if the vhf transmitter is working.. one way to find it is use oscilloscope, of course, but how i use it with out damage?
thanks

It is easy to do it. Attach a 50 ohm dummy load to your transmitter and then attach at the same point (t-connector) the scope 1M probe. This way you are doing the measurements on 50 ohms without damaging the scope

 

[vfone]

Especially for aircraft transceivers, is not recomended to verify its output transmitted power using an oscilloscope. You need an RF power meter.

For high output power transmitters, using a 50 ohms load, doesn't guarantee that the oscilloscope (used to measure the RF voltage across the load), will not be damaged if the voltage exceeds the scope spec limit.

 

[FvM]

I'm not under the impression, that the question addresses higher transmitter power, we rather expect a few mW.

If power transmitters are meaned though, oscilloscopes and probes have clear specifications for acceptable level, also in the VHF range. In case of doubt, you'll use attenuators. Standard attenuators have 1 - 2 W rating, for higher transmitter power, you'll refer to power attenuators.

The original question is about transmitter circuits and antennas, by the way.

 

[Epontes]

Thanks for attention.. the problem is, here, where I live this instrument is so expansive that my company doesn’t want buy it. Than, sometimes I have to
get by.. one more time thanks for attention, I have less then 24H subscribed in this site and all you are help me so much.. let’s go on help each one.. peace !!