What are you trying to do? You can probably achieve what you want to do with an op-amp.

Albert i have a very little signal of few mV 22.5 mV that i need to livel it lets say by 10 times , no current needed, few mA is okay .

radium98 wrote: ↑Fri Oct 07, 2022 9:25 am Albert i have a very little signal of few mV 22.5 mV that i need to livel it lets say by 10 times , no current needed, few mA is okay .

Radium

You could look up "RF Antenna Amplifiers" There are thousands of examples available!

Whether you choose to use a Bipolar or Jfet? Most designs are pretty linear, simple to construct and have a decent gain!

Just keep an eye on the "Ft" for your required bandwidth!

yellowbeard wrote: ↑Thu Oct 06, 2022 4:31 am All of the advancements like this, the MiniVNA and HackRF One are a part of a revolution brought about by software defined radio. The computer Johnny's are doing man-sized jobs in the field, and I used to curse them out when they started taking over the pages of my favourite electronics magazines. It's a far cry from the days of old with bottles, rollercoasters and variable toast racks.

I know exactly how you feel YB!

Whilst this tech is useful us oldies, I am glad that i grew up learning the "traditional" way of doing things!

I have noticed recently that "Pirates" with excellent coverage lack on audio quality due to computerised systems, They seem to sound MP3ish!

I hate to brag! But my "Oldskool" transmissions sound Warm like a fresh vinyl outta the sleeve!

Sinus , the problem is that voltage is coming from an Swr signal . it is not Rf .
thanks.

radium98 wrote: ↑Sat Oct 08, 2022 1:07 pm Sinus , the problem is that voltage is coming from an Swr signal . it is not Rf .
thanks.

As Albert said, probably the easiest and usually most convenient way, is to use an op-amp. You can define the gain you want, with the feedback network.

Thank you Shedbuilt

0.1-2000MHz RF Wideband Amplifier High Gain 30dB Low-noise Amplifier LNA Development Board

https://www.aliexpress.com/item/32964116656.html

rigmo wrote: ↑Tue Oct 11, 2022 10:33 pm 0.1-2000MHz RF Wideband Amplifier High Gain 30dB Low-noise Amplifier LNA Development Board

https://www.aliexpress.com/item/32964116656.html

It's useful as a buffer amplifier after an oscillator, but not for much else.

Albert H wrote: ↑Wed Oct 12, 2022 1:44 am It's useful as a buffer amplifier after an oscillator, but not for much else.

what would you take for more?

Albert H wrote: ↑Sun Oct 02, 2022 11:46 pm The way we used to do it (way back in the mists of time) was with an Absorption Wavemeter.

An absorption wavemeter was my instrument of choice too, for a long time. I tended to use an analogue radio, with a decent front end, in conjunction with the wavemeter. The radio, tuning across the broadcast frequency, tells a lot about the close in “noise” and spurii, with the wavemeter to look over a broader spectrum, and at the harmonics. Later on, I bought one of the TSA1000 Spectrum Analyser attachments - to use a scope in X+Y mode, as a spectrum analyser.

I was lucky. My first Spectrum Analyser (that I've still got) was an HP 141T storage 'scope frame with various front-end plug-ins. I've got the HF one that goes to 120 MHz, a VHF one to 1 GHz, and a microwave one that goes to 22GHz. Later on, I got an Agilent one, and an Anritsu (cheap job, but OK). I also have a Marconi Mod Meter, an HP Network Analyser, several Dummy Loads, Bird and Green power meters, and various counters, multimeters, HF voltmeters, lots of 'scopes of various kinds, and much more..... Over many years, I just seem to have accumulated several workshop's worth of Test Gear, usually bought from second-hand brokers (Stewart's of Reading used to be a favourite), and I've been selling off a few of the older, less convenient bits of gear....

As soon as I got into electronics - back in the 60's - I realised that an oscilloscope was an engineer's "eyes", and that was the very first bit of kit I bought. I got a Telequipment D52, which (at the time) was pretty sophisticated because it was a true dual trace instrument. I learned a lot from actually seeing the action of circuits graphically.

I still find it hard to believe that people want to try to build broadcast gear without any test gear!

Albert H wrote: ↑Thu Oct 13, 2022 3:20 am I still find it hard to believe that people want to try to build broadcast gear without any test gear!

Indeed. I learned quickly that I would get nowhere without test gear, which led me to things like wavemeters. It's probably less obvious to those starting out these days, because of the availability of working designs, kits, modules, many of which are "no tune". Most of these are also deceptively simple, where simple but good stuff, especially broadband, is deceptively difficult to design.

sinus trouble wrote: ↑Mon Oct 03, 2022 12:44 am You could also do it with a decent scanner?

It can be done!, you would want a clean transmitter to compare it against, it depends on the power of the transmitter, it is quite slow, may lead to mechanical failure of the scanner if it is done often. You would set it to wideband mode, jumping up in 1mhz tuning up above the fm band, what you would be looking for was something with just the transmitted audio on, not something which is a mixture of other signals.
It would quicker using a tiny sa, you see the spectrum straight away, you would use it with the telescopic antenna that comes with it, you would not connect it directly to the transmitter as cher would say thats not the way. You would set the transmitter up with the aerial you would be using the power, you would want to see nothing between the harmonics, a lot of extra uniform signals means a mismatch with the antenna, maybe under volting the rf amplifier. Having a little scanner is quite useful for seeing the signal strenght, mine is like an old friend, I wouldn’t be without, you can also tune to signals in the airband, see what frequencies are used.

A transistor perhaps?

Hii radium98.
That mens you are looking for a 30dB amplifier. In what frequency band?

Hi zulu53 it is solved , thank you . I was needing to amplify signal coming from swr coupler to feed a little protection .

yeah for something really low power you could use a transistor, I managed to amplify the signal from my signal generator with a general purpose one..

Thanks