Hello
I'm new here ,and i need some help or advice from you , I'm already done with success building PLL FM(88-100mhz) transmitter 4 stages the output power is 15W .
I need to increase the output power more , my friend gave me RF Transistors (MRF650) for free but it's use for UHF amplifier,
The MRF650 , 50W , up to 500Mhz

So the Question is:
Can I use the MRF650 as FM 88mhz-100mhz RF amplifier Transistor ?
And can you help me how to use it ?

 

Why not? MRF650 just has more bandwidth than you need.

 

Thanks for your reply
Look at the circuit , if l replace TP9380 Transistor by the MRF650 , will the rf amplifier work well ? Do i need to change the values of some of the capacitors or inductors ?

 

Compare the two datasheets and you will notice some significant differences.
The MRF650 is designed for 12V operation, not 28V.
The output capacitance is much higher.

 

What you have done is illegal and what are wanting to do is illegal in most jurisdictions. This thread should be locked.

 

What you have done is illegal and what are wanting to do is illegal in most jurisdictions. This thread should be locked.

Only if the signal radiates. He can drive a cable system with it. AKA closed circuit FM broadcasting.

 

Simple replacement of transistors is not good. Different transistors have different input and output impedances. Therefore, other matching circuits are needed (other values are capacitors and inductors).

 

Hello
I'm new here ,and i need some help or advice from you , I'm already done with success building PLL FM(88-100mhz) transmitter 4 stages the output power is 15W .
I need to increase the output power more , my friend gave me RF Transistors (MRF650) for free but it's use for UHF amplifier,
The MRF650 , 50W , up to 500Mhz

So the Question is:
Can I use the MRF650 as FM 88mhz-100mhz RF amplifier Transistor ?
And can you help me how to use it ?

In the US 88-100Mhz is used mainly for TV
for Europe http://rspg-spectrum.eu/wp-content/uploads/2013/05/rspg10_349_report_futureradio.pdf see page 32

I am not sure if government people in Us and Europe are happy with an extra transmitter @15Watt or more.

Picbuster

 

In the US 88-100Mhz is used mainly for TV
for Europe http://rspg-spectrum.eu/wp-content/uploads/2013/05/rspg10_349_report_futureradio.pdf see page 32

I am not sure if government people in Us and Europe are happy with an extra transmitter @15Watt or more.

Picbuster

Wrong. There are no TV stations at all in the 88-108 MHz. band. In fact the former VHF spectrum of 54-88 MHz (channels 2-6) and 174-216 (channels 7-13) MHz has returned to whitespace since the advent of digital TV broadcasting.

 

In fact the former VHF spectrum of 54-88 MHz (channels 2-6) and 174-216 (channels 7-13) MHz has returned to whitespace since the advent of digital TV broadcasting.

Not true in the USA. There are still plenty of VHF low-high stations on the air with digital stations. There's a lot of misleading information out there that says that all HDTV channels are UHF and it's just not true.
https://nocable.org/availability-report/zip/97266-portland-or
https://www.antennasdirect.com/hdtv-station-list.html

 

Those lists are kinda hard to read and it seems those remaining VHF-low and VHF-high stations are not widespread. Portland? Abeline? Backwaters.

 

Those lists are kinda hard to read and it seems those remaining VHF-low and VHF-high stations are not widespread. Portland? Abeline? Backwaters.

Not really all backwaters but even if it was that means the spectrum is not whitespace. Look at the POST DTV RF channels across the nation. The recent FCC auction that sold UHF spectrum is sending more stations to the VHF-high channels in some markets.

 

Most of EU cities the local FM band radios work at 88-108 MHz, typically few dozen stations at each city. Thus, this range is tightly used. Contrary, 56-88 MHz was and still is used for russian FM stations what created so large problems to near neighbour countries TV, that they ( I mean mainly three Baltic States) had no other way as to condemn the TV air 3rd channel (56 MHz). At least at my home my SDR stick shows the EMI from russian radio network at this frequency about quarter of local TV signal. The distance to russia boarder yet is about 300 km, thus their antennas seems be very high up-sky.

 

Backwater or not makes no difference. It is what the FCC rules specify. ALL BROADCASTS ON THE FM BAND MUST COMPLY WITH PART 15 OF THE REGULATIONS, OR, MUST BE LICENSED IF THEY DO NOT! >>>PERIOD!<<<< Any transmitter capable of transmitting more than about 200 feet exceeds part 15 regulations and thus must be licensed. A 15 watt transmitter will drastically exceed this limit. Of course it you are in a foreign country the rules differ. MOST ARE MORE STRICT! Usually, for the first offense (USA) the consequence will be equipment confiscation and a warning, but you may have a criminal record. Doing illegal things can really screw your life up good, so consider this before building unlicensed transmitters and broadcasting.

 

Wrong. There are no TV stations at all in the 88-108 MHz. band. In fact the former VHF spectrum of 54-88 MHz (channels 2-6) and 174-216 (channels 7-13) MHz has returned to whitespace since the advent of digital TV broadcasting.

you are correct I looked at the wrong line see https://transition.fcc.gov/oet/spectrum/table/fcctable.pdf page 20

Picbuster