hmm , as there is a vox, there is a possibility to add a PTT line, I will dig up the schematic to see where a mod needs to be done.
Posts by on4iq
yes, the input power is dumped into the resistors ( and 6watts is a lot to dissipate), after this 50ohm/6Watts dummy a portion of the power is taken by the pot meter to drive the up convertor. I havent checked the min. drive needed when you bypass the vox ptt and make a hardwired ptt . But given the type of mixer, the MCL ADE-35 is rated at 50mW, ADE-35+.pdf (minicircuits.com), a lower drive below 50mW is definitely possible if you bypass the input ATT resistors.
there is input attenuator in the upconvertor, and the level can be set with pot meter (pwr adj potmeter)
(top middle of the pcb) So higher drive levels are possible.
[Blocked Image: https://www.dxpatrol.pt/images/mk4a.png]
did you try firstname.lastname@example.org ?
i got reply within 1 minute from Antonio
i got several gps running, the GS shows 4 or 5 sats, that is inside house next to the window.
The BG7 gsp shows 8 or 9 at the same spot.
The warmup time is not an issue to me, it takes 10 min. to setup my portable system.
And i start connecting lnb to GS and switching it on. So all is warmed up correctly by
the time i get all in place.
here is the answer ( always better to ask dxpatrol instead of bashing)
The battery is not needed in this case
because we are using Ublox-7N which has flash memory.
On the board we leave the battery holder in case we need another Ublox without flash memory.
The 8 to 10 minutes delay is not due to the GPS, it´s the OCXO oven Xtal oscillator that needs to heat to 60ºC and stabilize the internal temperature.
It´s a price we have to pay to have a clean stable signal in 10Ghz in any weather/room temperature conditions.
i asked Dxpatrol abt the battery
they are all the same, i have 3 of them.
Its the lo freq that sets the if downband.
There is not much spreading in NF and they should provide excellent RX, even with 60cm dish.
beware of these far east pigtails. I used one to and swr was really bad. Swapped it to jumper i got from cellular phone base station. Swr perfect. Would suggest you download last version of the gs manual and look at the cable chart
Actually the lnb still get its 12v in RX, but another LO In freq instead of the 25MHz goes above 30MHz (not at same level, bleed through the pin diode switching)
I had a simple approach to the thing, add another source of LO to the LNB, which doesn't change on TX, so plain simple fixed one.
(its just PIN diodes for rx tx switching, D4 going to C15 and IC1 divider and 25/30Mhz out to LNB LO input , the LNB LO input needs to be swapped to the other LO source.
Only thing is that me using 432MHz also on 2nd receiver as IF (same rx freq as TX freq on transmiter) wasn't an brilliant idea...
(but I do hear my voice :-o )
But the next thing will be adding a dxpatrol downconverter PCB in the box, so that in RX i can use 1296/144/28 as IF.
You could add a basic downconvertor with plain 25MHz source and get the 739MHz for your sdr rtl stick. Or find a small sdr radio with panoramic display (still looking for a decent one) e.g Malachite Malahit for one of the above mentioned IF freq's.
The dx patrol PCB will nicely fit in, just need to drill the extra holes in the backpanel. And I can choose to run the RX on 28/144/1296 (duplex radio), or go simplex and use a websdr, by swapping the LO output to the LNB , or even add a relay with front panel switch for the LO.
It is a very basic diagram 😀, I voluntered to rewrite the manual, and in v1.2 you will find clear indication that it is simplex station , and as per amsat request the operator must be able to rx his own signal (websdr or seperate downconvertor).
I am inprocess to make a modication available to add the extra RX on other band 28 144 or 1296. Just awaiting one more part to test run it, and see how easily it fits in the box..
Looks like DD1US Matthias has the solution already.
And limit your power so that its not stronger than the beacon..
as time passes the 1st mods on the grounstation have been done.
My unit has external ptt control added already.
At the moment i'm looking to mod the rx circuit to have the rx splitter inside so that the sdr stick can be put inside the box.
The backplane of the box has room left for a usb receptable.
Would be less cabling .. and an answer to the duplex question.
The RX setup (SDR-RTL stick) is used as wideband RX monitoring.
I see the whole band and where there is activity.
I see the tuners drifting over the band and see where they stop,.
And the unit does not violate any rules at all.
It all depends on how it is used, so down to operator.
(just like those transmissions that are stronger than the beacon)
If you use a nice sdr (with the added advantages) you play nice.
ps1: I have made ZERO QSO on the QO100 bird, playing just on RX for a long time.
ps2: when I saw the unit advertisement, it was clear to me that it was simplex unit.
I sold my seperate dx- patrol up down convertor (144/432) , which was full duplex, but to much cabling, GPSDO, seperate amp etc etc
Main reason for getting the DX-patrol GS, that it had all in a box, up/down/gpsdo, and its small, very small size to take in hand luggage.
I even got the dxpatrol helix antenna as the size compared to poty and LNB is smaller.
I considered DXTO from India (as that one has a 28MHz IF) which would have been cheaper on the IF rig , but price +taxes scared me off.
Now just need to get a small dish antenna that will fit the luggage as well (after the covid pandemic)
And to stay in the sat footprint when picking a location.
Hello, I got the new GS from DX-patrol monday.
A few remarks about the duplex, yes the unit is not duplex, so what.
advantage: if i turn on 70cm and hear a station in downlink, I know i am on the correct uplink.
I have been listening a few weeks on QO-100
I see the tuning carrier from a lot of stations going over the band till they are plus minus on the situation they want to work, not good
I hear a lot of stations up to a few hundreds of Hz above and below the station they want to work, not good
I hear a large number of stations who are extremely loud (just above the beacon level), sound to me they want to see when Leila kicks off,, not good
There is nothing wrong with QO100 simplex groundstation, on the contrary, the whistling and hola is not necessary anymore....
Have I got full duplex, yes (otherwise i could not see the whistlers going across the band).
How was it done?
I split the RX signal coming from the LNB to a SDR stick (the splitter has a DC by pass on one port so that LNB works OK)
Using SDR consoles V3 get radio and stick nicely synchronised.
A few more things about the QO100-GS:
- it is vox operated, 2 VOX (one for PA and one for transvertor), both inside
-there is provision for a hard line PTT, (F6-1 F6-2 connector), short them out for PTT.
One thing is that you might need to connect the external PTT of the amplifier to the F6-1 line aswell
The lock (from the OCXO takes just abt a minute.
The lock from the satellite takes a few minutes.
Now let the flames come