Posts by DG9BFC

ANYBODY WANTS TO PLAY QO100 BINGO ?!?

wie hoch?? VOLLDAMPF

verzögerung ist quasi nix (keine 800ms)!!

problem is that you installed the genuine fw from AD (0.38) ... that is "too new" to work with the datv fw by evariste

in older installs i used fw31 from analog devices and then installed 2103 from evariste (quite similar to the 0303 version)

now i am using the very new fw from evariste (0.3-31) that does not has the web page anymore but can be controlled from "node red" gui

fw can be found here

beta – Google Drive

also read the wiki

Home

PlutoSDR softwares using custom hdl design. Contribute to F5OEO/pluto-ori-ps development by creating an account on GitHub.

github.com

da kann man sein Signal schön verhunzen wenn man diesenTx Filter FALSCH einstellt .. genau dann entstehen diese Geistersignale

am besten auf 50% stehen lassen und NICHT weiter reduzieren ... ja ich weiss durch Reduzieren bekommt man mehr Ausgangspegel (aber eben auch Geistersignale die man nicht will) ... je nach eingestellter Bandbreite im Pluto (576 oder 768 oder was auch immer) kann man durch reduzieren dieses Tx Filters mehr Ausgangsleistung erzeugen .. aber wenn man das falsch einstellt gibt es unerwünschte Nebenaussendungen

je nach Bandbreite gibt es da werte die gut fuktionieren und einstellungen mit fürchterlichen Werten

wenn man nicht genau weiss wie man das einstellt FINGER WEG (also 50% default belassen)

meist braucht man diesen erhöhten Pegel nicht und die default Werte passen

why didnt they add a series cap between input and transformer?? cause the puto was not planned as an rx tx device for us ... but as a "toy for students" to play in the classroom with only the rubber ducky antenna

hier findeest du die Fw von Evariste

https://github.com/F5OEO/pluto-ori-ps/wiki

damit funktioniert die Ptt steuerung

im Pluto ein 5V Relas verbauern and GPO 0 und 1

Am besten du nimmst gleich ein 2 poliges Relais und schaltest mit einem Kontakt die Vorstufe und mit dem anderen Kontakt die Ptt von der SG-Lab Pa

dann ist beim Booten die Vorstufe aus und die Vox der Sg-Lab pa spricht nicht an

obwohl die Pa eine Vox hat IMMER auch die PTT benutzen ... sonst kann man zB kein FT8 mit geringem Pegel machen (weil die Vox nicht anspringt bei kleinem Pegel)

Nimm einfach die datv fw .. da hat evariste auch eine neuere geschrieben (von diesem Jahr im August)

siehe hier

https://github.com/F5OEO/pluto-ori-ps/wiki

mit der fw funktioniert die ptt einwandfrei (habe ich hier seit Monaten im Einsatz)

dazu eine Schaltung mit 2 Transistoren und einem 5V Relais und fertig ist die Laube

gruss sigi dg9bfc

Quote from G0MJW

Peter,

Experimenting is always a good idea. A patch antenna with a single feed that is perfectly circular can't produce circular polarisation. There needs to be something else. I settled on the dual resonance method. The original POTY (it was not called that, that was Remco's idea) used an ellipse but that's hard to make, so I tried an approximation to an ellipse. A circular patch with notches, circular with tabs and the square with cut outs. The square was good enough and is easiest to make with simple tools, so that's what I ended up with. Other iterations had directors, choke rings and so on. Another way to do this dual resonance trick is with a feed and a tuning capacitor, but I found that really hard to get just right. G3RUH managed it but not with the waveguide. Achim did manage it but I don't know exactly how.

What wasn't obvious early on is were the simulations accurate? I was taking huge liberties with the meshing in the simulation and with the full version of CST we could probably design a more forgiving, broader band patch. In the end, its only when something is reproduced in hardware that you can be sure it works, or not. So, keep on cutting and trying because if it works in hardware, even without simulation, it works.

Mike

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it was me who brough mike to the idea of the square with the cut corners (i have no lathe so peters feed was not easy to reproduce on the kitchen table) .. i calculated in sonnet lite and mike calculated in cst studio ... and end result was near identical

rest is history

difficult to build and tune ?? yes a bit ... but when exactly made shows a good circular pattern and is near spot on

i use big spring loaded clamps to hold the two plates pressed against the spacers (i use 3mm stainless steel rods) not only gravity

that helped a lot to have exact distance

fifth harmonic is 12ghz (5x2.4) and can desense (with lower power) or kill the lnbs first transistor stage

and 12 ghz is easy travvelling inside the waveguide (its build for 11 to 12ghz .. not?!)

an overdriven and clipping amp produces higher fifth overtone

so stay low in power and stay linear (plus a lowpass filter inside or behind amp)

that lowers the signal on 12ghz that otherwise... see above

with a better lens and a better position you can improve your rx and tx signal

either hack away from a commercial rocket lnd or print your own (drop me a mail if you need a print file)

reflector should almost touch the lnb clamp

try to avoid angled connectors (they produce more loss as half a metre cable bent in a nice wide open curve)

greetz sigi dg9bfc

oder eben eine selber drucken oder von einem befreundeten ömer drucken lassen

and ... how does that poty work?? in principle it is a too long and a too short dipole as a cross ...both fed with the same current

now what does a too long or too short dipole represent?? a radiator with a coil and a radiator with a cap inline

and what does a cap/coil do?? they shift phase

now ... if proper designed and tuned one element shift phase plus 45 degrees and the other shifts - 45 degrees .. voila 90 degrees difference (but with equally currents!!) and we have the circular polarisation

and we do see that if the difference between the upper and lower resonances are around plus minus 2-3% (around 50 to 70 megs or 25 to 35 megs above/below working frequency)

means the mechanical dimensions should NOT be changed and the feeding point must be at the absolute exact position to feed the elements with the right phases and current (and have the 50 ohms on that spot also with not reactance added) ... not easy but it can be solved with ... build it EXACT ... and finetune in very small steps with looking on the vnas smith diagramm (not to mention use a short cable and tune the cable out with osl calibration etc)

a hint .. in several poty i made i had to slightly get the long edge near the feedingpoint a tiny bit closer to the reflector .. about half of a tenth mm only or so

greetz sigi dg9bfc

ps yes if proper tuned the circular polarity is good! and a single resonance spot does NOT mean both elements are tuned to the same single resonance .. BOTH TOGETHER form a single resonance with circular polarisation (see explanation how the poty works at the beginning of this text)

if that dip is at the working frequency AND if that is at the top of the rollercoasterloop then it is perfectly tuned

install it ...

with such a high return loss you will see the return loss will go down a bit from your 50 or 55 peak cause you see the reflections from the dish back into the feed and any slight bending will detune that very deep notch ... a bit of distance change and the reflections come back in a different phase related to the tx energy and you see that deep notch again (will vary a few db depending on distance) ... if you have made your reflector from a not too thick copperplate then you should reinforce it a bit (i glued a HPL sheet at the back for a few feeds i made for cf dish)

does the switching back and forth work on all fw versions?

using evariste 2103 here with a patch for easier datv settings

... cant wait to try it out here

dg9bfc sigi

you can add a rim to the reflector (say a patch feed driven tubular waveguide) ... that can WIDEN the angle for f/d 0.25 to 0.3

and ... as deeper the dish as more you have to look that the feed is at the phase centre ...for a patch with rim that means to place it a bit more away from the dish

i have the same problem with picture freeze after a second but audio still works

any hints what it may be?

beaon decode works fine but i see that on several ham signals its difficult to find a lock

and even if locked not always a picture is shown

hm ich sehe das heute auch .. bild nur der obere teil .. ton läuft (dvbs gui und vlc player)

und wenn man die poty antenne RICHTIG abgeglichen hat ist die auch schön zirkular

only way is an lnb with external reference (gpsdo or at least on ocxo or tcxo in shack)