Looking for RX front end schematic

[mattijs321]

I'm looking for a schematic to hook up to an untuned dipole antenna for 40 or 50 Mhz

I guess it'll probably be something along a three stage transistor with variable L and C in collector and/or emitter lines.
I guess that's the way it's done in RC rx's too seeing most have 3 variable L's on the pcb's.


The TX is a plain 50 or 40 oscillator (SG615P-50MHZ 50PPM — EPSON TOYOCOM — CRYSTAL OSCILLATOR, SMD 50.000000MHZ)
with a tether on the out pin.

I'm hoping to pick up the signal at about 100 meters from antenna.

Two dipoles will be used and phase will be compared with logic gates to obtain angle at which TX is relative to the two dipoles.

(it's for the water bottle rocket project i'm still working on...for those who contributed in that thread...and probably remember me completely srewing up ;) )

[RX5]

http://www.rcgroups.com/forums/showthread.php?t=667712

try THAT for front end... there are 2 RF amps there.. the 1.3W ad the 1.5W.... @ 50MHz also... pls post results... dont have THOSE transistors.... hope this helps

[mattijs321]

wait a minute, isn't that a TX ?? have to look over the thread more carefully

[RX5]

ooops :D

[mattijs321]

anybody?

all i need is the front end transistor schematic :/

[macquen]

anybody?

all i need is the front end transistor schematic :/

OK you ask I have.........................I originally sent wrong files these are ok

73 - steve - WB2TMR

[mattijs321]

shoot...i was hoping it'd be a little easier...is that a DIY RX ?

[AndyOne]

Modern designs use MOSFETs in the front end to get better crossmod performance the bipolar transistor design looks about 1970s vintage to me.

Andy.

[mattijs321]

maybe an RC RX front end isn't even what i need in terms of complexity.

I just need to receive an unmodulated 50Mhz wave from a model rocket with two dipoles and use those signals compared to each other to know at what angle the TX is.

[AndyOne]

The easiest way of making a direction finder is to use a receiver with two antennas in a switched arrangement, see this thread...

http://www.rcgroups.com/forums/showthread.php?t=374263

Any receiver that can resolve NBFM on the frequency should work.

Andy.

[vintage1]

maybe an RC RX front end isn't even what i need in terms of complexity.

I just need to receive an unmodulated 50Mhz wave from a model rocket with two dipoles and use those signals compared to each other to know at what angle the TX is.


Well about 30 engineers including for a short period, myself, did all that back in the 60's for something that became one of the few anti-missile missiles ever to have shot down a missile in actual combat. Google "Sea Wolf."

I think the project was in the tens of millions hen I left it in 1969, and by the time it was in production, billions.

Beam riding rockets are fun though, but it might be cheaper to put an ex-soviet one on the black market :D :D

We ended up with three separate microwave receivers, three carefully adjusted, and auto calibrating IF strips and a three way phase comparator so the rocket would know if it was 'on beam' or going off beam. Plus safety systems to autodestruct if it lost the beam for more than half a second.

There was a bit of a fuss when someone realised it would be just passing the ships bridge after half second and wouldn't be IN the beam at that point.

Fortunately that thought occurred before it was test fired.

[mattijs321]

The easiest way of making a direction finder is to use a receiver with two antennas in a switched arrangement, see this thread...

http://www.rcgroups.com/forums/showthread.php?t=374263

Any receiver that can resolve NBFM on the frequency should work.

Andy.

that's essentially what i am going to do...except i don't need to switch the antenna's or something to produce a beep...instead the two signals (from the two fixed antenna's) get boosted up to the point where they're block signals and then they get EXOR'ed, low passed and sampled to MMC

I don't need to track something to find it....i need to collect data about the path of a small rocket, so all the data interpretting is to be done afterwards in a mathematical model...not with with my ear in real time


what i'd like to have is the EASIEST way to get a dipole or even monopole antenna signal and filter it with the least components possible to obtain the clean 50mhz wave being sent from the rocket with a SNR that enables the rest of the schematic, with limited hysteresis, to do it's job...and to function ;)

I had some antenna basics a couple years ago, but i don't have the books anymore....and there are alot of FM and AM schematics on the web but i can't find simple balun data etc for 50 mhz and simple filters suited.

I could design a chebychev or something..but due to my limited experience with RF i don't know what components to use at that frequency

[mattijs321]

Well about 30 engineers including for a short period, myself, did all that back in the 60's for something that became one of the few anti-missile missiles ever to have shot down a missile in actual combat. Google "Sea Wolf."

I think the project was in the tens of millions hen I left it in 1969, and by the time it was in production, billions.

Beam riding rockets are fun though, but it might be cheaper to put an ex-soviet one on the black market :D :D

We ended up with three separate microwave receivers, three carefully adjusted, and auto calibrating IF strips and a three way phase comparator so the rocket would know if it was 'on beam' or going off beam. Plus safety systems to autodestruct if it lost the beam for more than half a second.

There was a bit of a fuss when someone realised it would be just passing the ships bridge after half second and wouldn't be IN the beam at that point.

Fortunately that thought occurred before it was test fired.

I imagine it was probably mostly analog...was the control system hard to develop ? Back in school i had a couple of hours of microstrip antenna's for rockets and i remember seeing an image of a rocket kinda like you are describing.

How were the parameters for the control system developed? Did it have a gyro or accelerometers or did it only have RF input fed into the control loop?