Simple VHF Amplifier??

[panic mode]

do you mean 145,650 MHz (145.6GHz? Or MHz?)

he is from Europe there is no decimal point, it is decimal comma.
for someone used to write in that format (ie. pi=3,14) it may be all too easy to forget that
on the other side of the world people are used to using dot (pi=3.14).

QRP is good example of using low power to get long connections. getting far with little radio power is actually not a problem, challenge is obstacles. at frequencies sufficiently high (100MHz is high) radio waves propagate more or less straight (line of sight). this is why you will not hear FM radio (88-108MHz)from town that is 200km away or on other side of the world - even though they use powerful transmitters, you only pickup local stations.

HAMs often get connections around the world using only low power and reflections of ionosphere - when working with lower frequencies (up to some 20MHz or so and when ionosphere is low. that is why you get more AM stations, specially at night when ionosphere is lower (and incidence angle changes).

I am not surprised about getting 230km range at 1 or 1.5W, but getting that range using 143MHz would need line of sight. imho there is either a depression between both locations that are 300m above sea level or some other factor that was not mentioned (perhaps another repeater?).

 

[ericgibbs]

This link gives the global use of the decimal point or decimal comma.

Note: the UK is a dp.

https://en.wikipedia.org/wiki/File:DecimalSeparator.svg

 

[panic mode]

ok fine, i should have put "continental Europe"

 

[Willen]

-QRP is good example of using low power to get long connections. getting far with little radio power is actually not a problem, challenge is obstacles. at frequencies sufficiently high (100MHz is high) radio waves propagate more or less straight (line of sight). this is why you will not hear FM radio (88-108MHz)from town that is 200km away or on other side of the world - even though they use powerful transmitters, you only pickup local stations.

-HAMs often get connections around the world using only low power and reflections of ionosphere - when working with lower frequencies (up to some 20MHz or so and when ionosphere is low.
I am not surprised about getting 230km range at 1 or 1.5W, but getting that range using 143MHz would need line of sight. imho there is either a depression between both locations that are 300m above sea level or some other factor that was not mentioned (perhaps another repeater?).

-What is the theory of QRP? What is it? I am googling too. It is so interesting to me.
- I know, due to reflection of ionosphere, low friquency can travel to all around world. But here is 143MHz and high friquency cannot reflect on ionosphere. In straight line of sight without obstacles, 1.5 watt tx can transmit 240 KM!!! It is totally new thing to me......

 

[panic mode]

the idea is to use small power to make long distance connections. ideally the small power shall be 5W at transmitter output or less.
antennas are the key. so they go to great length to make sure the antenna is high gain and matched perfectly.

 

[Willen]

the idea is to use small power to make long distance connections. ideally the small power shall be 5W at transmitter output or less.
antennas are the key. so they go to great length to make sure the antenna is high gain and matched perfectly.

I think they use Yagi or horn antenna (?). If so, can I convert my 1 watt Fm tx into a QRP by modifying my verticle dipole antenna into high gain antenna?

 

[panic mode]

in 100s of MHz Yagi is used commonly as high gain directional antenna. at those frequencies line of sight is restriction. QRP as i know it let you communicate with someone on the other side of the planet using only few watts. this works at lower frequency bands like 3.5 or 14MHz and antennas here are large. you can find more at
https://www.dxzone.com

 

[Kryten]

he is from Europe there is no decimal point, it is decimal comma.
for someone used to write in that format (ie. pi=3,14) it may be all too easy to forget that
on the other side of the world people are used to using dot (pi=3.14).

QRP is good example of using low power to get long connections. getting far with little radio power is actually not a problem, challenge is obstacles. at frequencies sufficiently high (100MHz is high) radio waves propagate more or less straight (line of sight). this is why you will not hear FM radio (88-108MHz)from town that is 200km away or on other side of the world - even though they use powerful transmitters, you only pickup local stations.

HAMs often get connections around the world using only low power and reflections of ionosphere - when working with lower frequencies (up to some 20MHz or so and when ionosphere is low. that is why you get more AM stations, specially at night when ionosphere is lower (and incidence angle changes).

I am not surprised about getting 230km range at 1 or 1.5W, but getting that range using 143MHz would need line of sight. imho there is either a depression between both locations that are 300m above sea level or some other factor that was not mentioned (perhaps another repeater?).

There are noe other repeter in between but I get furhter line of sight becouse of elevation...

 

[ericgibbs]

hi,
This explains the Earth curvature LOS , line of sight

https://www.davidsenesac.com/Information/line_of_sight.html

 

[davenn]

I am not surprised about getting 230km range at 1 or 1.5W, but getting that range using 143MHz would need line of sight. imho there is either a depression between both locations that are 300m above sea level or some other factor that was not mentioned (perhaps another repeater?).

definately dont need LOS at 145 MHz for those sort of distances

D