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AmRadiant
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ok... many thanks!
In my country (italy) 2N3866 is very common... and costs about 1 euro.
But unfortunately 2N3553 is uncommon at all >:(
for 13.8 Volts supply... well I use that with 2N2219 (or 2N2218, too) without problems (heatsinked), so I presume that works ok with 2N3866... -
Ok, thanks!
I suppose that for higher output I must simply change Q2 and Q3 2N3904 with -for example- 2N3866, and use lower resistance for R6 and R8...
I use 13.8 Volts stabilized, so I presume I can cut away voltage regulator... -
hello all,
about this project:
http://www.electronics-lab.com/projects/rf/021/index.html
For my objectives only the first stage (oscillator T1) can be enough (100-150 mW at 13.8 Volts): so I must match this stage to antenna (50 or 75 ohm impedance).
What solution do you suggest?
1) using C7 L4 C8 instead C6 (but I think that impedance out from T2 is lower than T1... so I'm not sure)?
2) a socket directly to a coil from L1: I've tried from cold side, but from first wound power decrease significantly...?
Some ideas?
Thanks! -
many thanks ssa :)
Maybe a simple VK200 can do the work I think... like this project:
http://www.electronics-lab.com/projects/rf/001/index.html
that is very similar (well... enhanced ;D ) to the project above.. And I think I'll use a 2N3866 for T2. Maybe a madness, but I'll do some experiments (when I've a little free time) with a Peltier slab over heatsink for T2 and 28 Volts... I suppose that a simple fan isn't enough!
A little note about this project:
I don't think that is 'crappy' like someone said... remember that it can be made for about five-six euros and goes surely over 1 W rf power!
I've see (and assembled) project that use one only oscillator stage with a BC547 rated for 1 Watt at 15V :o ... and that is very crappy, not this one :D
Remember that, for irradiation, 2 watts or 3-4 watts is pratically the same...
So I must say that is the best projects with free oscillator, simple and cheap ever see. The first stage (that I've built) is fantastic, very versatile and incredibly stable.
But...
HOW ABOUT A LOWPASS FILTER?
maybe a lowpass 18 dB (PI) can be enough... but where can be put? above or below C7-L4-C8? -
Hello all, about this project:
http://www.electronics-lab.com/projects/rf/021/index.html
can you explain how to build L2?
I read:
RFC (resistance 1MOhm with wrapped around her inductor of enough coils from fine isolated wire. Scratch of utmost inductor and you stick in utmost the resistance making thus a parallel L-r circuit.)
:-\
but can exist a simpler way to build this? how can I substitute this REALLY critical assembling with some more practical solution?
Thanks!
P.S. the first stage of this trasmitter alone works very good as 150 mW - 12V transmitter, very stable and not critical at all. I've replaced 0~45pF trimmer with a 5-20pf one, and L1 with 4 turns 1 cm diameter (very wide turns): it works ok at 88 Mhz
FM impedance antenna matching
in Projects Q/A
Posted
ehm... yes, of course :D
with a dipole from TV antenna (using correct lenght for FM), the first stage from 2N2219 project seems to work very well about 800-1000 meters open space (13.8 Volts)... my tests.