Hello Technicians,
I need some help wit my OPTICUM LTP-04H Lot S/N:18-12-0:
I dissassembled it and I have som questions:
The crystal is on the backside. I removed it. It is connected to the 2 pads on the front (marked in the picture below).
1. Which pad should I use to insert the 24 MHz signal. The "Hot End" ? Which is it ? How can I find it with measurements ?
2. Can the crystal stay in place, when the "Cold End" is cut off ?
vy 73, Martin DL9SAD
OK, it seems that Opticum LPT-04H switched from RT320 to RDA367 chip...
Hi,
You marked 2 pads, i think it is the one closer to the RDA Chip. Inject your Reference there, test with a handheld Radio by transmitting on ~ 437.00 (*24 = 10489.2) and find the signal on your sdr program. If you find it, you picked the right pad.
Ideal zum neuen DownConverter V3d passt natürlich ein von AMSAT-DL fertig umgebauter LNB, d.h. modifiziert für eine Referenzclock direkt gespeist aus dem Down-Converter und dort durch einen hochstabilen OCXO oder TCXO+GPS erzeugt.
Weitere Details sind der Beschreibung des DownConverter V3d auf unser Webseite zu entnehmen.
Wichtig: die externe Referenz liegt nur am "WB" Eingang des Konverters an und muss dann entsprechend auch mit dem oben gekennzeichneten Anschluß des LNB verbunden werden!
Hier im Shop: https://shop.amsat-dl.org/produkt/qo-100-modifizierter-lnb/
Hi..
We got a few of these LPT04H lnb and the y show something strange.
When connected to 1 port it all seems good, bit high in the noise but very reasanoble..
But when i connect the 2nd port i and give power on that port the first port looses 3dB or more..
The freqency of the first port also changes..
There is no different witch port i start with but when connecting the second port to either NB (pluto) or WB (Minitiouner) the signals go bad on both ports.
The bias voltage is from the same source and just lowerd with some resistors and diodes...
Anny idea's...
Benno
Display More1. Which pad should I use to insert the 24 MHz signal. The "Hot End" ? Which is it ? How can I find it with measurements ?
2. Can the crystal stay in place, when the "Cold End" is cut off ?
Martin,
did you make this LNB work?
73, Paul
No, i think i fried it.
I broke the metal housing while removing the connectors. I would be very happy if someone could give me a hint where to buy which LNB that could be more successfully modified.
I've ordered two LT04H last year. Opened one and it uses a RT320M, 25 MHz X-Tal. Pictures enclosed. SN: 18-02-0 ...
Can anybody tell me the level of an external LO that I should apply (25MHz) to my triplexer?
Thank you.
At the moment we still have a larger quantity of the LNB LTP-04H from the 18-08-0 series, which are now being modified. We ask for some patience here
Any news on this?
Thanks
The Opticum Twin LNB LTP-04H up to the S/N: 18-08-0 xxxxx is in any case easy to modify.
For the S/N with 18-12-0xxxxx and 19-01-0xxxxx we are currently investigating whether a modification is possible with reasonable effort.
At the moment we still have a larger quantity of the LNB LTP-04H from the 18-08-0 series, which are now being modified. We ask for some patience here
Hello, I have a model 19-01-0xx. Any news about modification?
73's Gerhard
Opticum Twin LNB LTP-04H and S/N19-01-0xxxx is using RDA3567 and the crystal is on the backside. I think it is possible to cut one of the traces to the crystal right behind the Chip and before the via. LO input should be on the other trace, having a pad for soldering. Will try to modify and test.
This is the backside.
Tnx, so the two vias are the connection to the crystal and the two "pads" are the capacitors. I think is should be possible to leave the crystal, cut one trace and use the other "pad" = capacitor as part of a voltage divider / LPF. I did not find a data sheet of the chip, so I don't know which side is the output of the oscillator.
Today I have successfully modified the Opticum Twin LNB LTP-04H with S/N19-01-0xxxx.
I left the crystal on the backside. I have cut the trace beween "2" and RDA3567. I have cut the meander trace "3" and soldered 470 nH in between. At "4" I soldered 100nF to cut the DC path to the PLL. The reason is that I am using a L-C-L LPF consisting of 2x 220nH and 100pF instead of the usual series resonance filter.
At "1" I soldered 220nH. From the other side of this inductance I soldered 100pF to ground "5" and another 220 nH, building a LPF. The LPF was connected by a thin wire to the 100nF capacitor at "4".
The right F-Connector was used as WB connection of the AMSAT-DL converter with LO 24 MHz. Using just 1 meter of coax, the signal level on 24 MHz was sufficient to lock the PLL. Did no further level tests for the LO at the moment.
The cover has to be grinded between "1" and "5" not to have a short circuit.
Test with a little 10.5 GHz radar source was successful.
Tomorrow I will hook the LNB to my POTY and I hope I can report sufficient sensitivity and LO stability afterwards.
73's Gerhard
Yes indeed, no stock for weeks
73 de Frank PH2M
Ordered this LNB + the downconverter today 
, looking forward to get them using together with my IC-9700 + SG-LAB transverter 
Can anybody tell me the level of an external LO that I should apply (25MHz) to my triplexer?
Thank you.
No one. Ok. I've measured 800mVpp.
Hello,
I just modified Opticum LTP04H Twin LNB serial No.19-01-0xx
Left F connector for 25MHz reference (Leo Bodnar GPSDO, 8mA drive), right F connector for IF output (no mods).
The original 25MHz crystal left on its place (bottom side), just one track to RDA3567 cut, see photo. So the external reference is now fed via the old crystal.
I soldered the 1nF in ref input because I broke the original C when opening cover. Maybe it can stay as is, I don't know what its value was.
The 49.9 ohm is not necessary, it works also without.
Regards, Marian
