• Salve IK4IDY, questa dual-band e' fatta apposta per avere polarizzazione VERTICALE in salita e circolare destra ( inversione della sinistra ) sul disco, giusto per lavorare il sat come si deve......tutto qui.....73!


    Hi IK4IDY, this dual-band is made to have VERTICAL polarization in ascent and circular right (inversion of the left) on the disk, just to work the sat as it should ...... all here ..... 73 !

  • Hi folks,

    thanks for the positive reactions.

    As soon as the price is fixed and orders can be made, I will announce it here as well.

    The first series of duoband feeds will have only one polarization plane for 10 GHz. But generally two levels of polarization are possible!

    The duoband feed is made of aluminum and it is expected to be anodized.


    Peter, DJ7GP

  • Hi,


    Its not so difficult to build simple feed for 13cm uplink. During two last evenings I was made a simple 5 turn helix feed. I'm planning to use it for P4A uplink with second 80cm dish. At this time I havent swr bridge for advanced measurement, but I was made a simple test with Kuhne MKU UP 2424A. It probably seems that my homemade helix feed has low broadband swr.

  • Hi Raf,

    I am just building nearly the same solution and want to insert a small rocket LNB so that this could be used with one dish for RX and TX.

  • Hi Heiner,


    Its a good idea to make helix feed with integrated LNB. I was thought about this solution however its not easy to do even with MKU LNC - external diameter 40mm. Im afraid also about internal influence between 10w RF in helix and sesnitivity circuits in LNB inside helix coil. It may damage sensitive electronics inside LNB. For stationary work I will use two antena system. For rx 100cm dish with Kuhne MKU LNC and 80cm with homebrew 5 turn helix for txing.


    For portable holiday work Id like to build integrated solution - 60cm dish with 4 turn helix and this LNB inside:


    https://www.dimaxa.de/empfangs…dlb-sinl20-multi-opp.html


    This lnb has 23mm mount diameter. Easier to adapt it inside helix coil then lnbs with 40mm mount diameter. This lnb isnt so expensive like MKU LNC, cost only 6,90E and if will be damaged during first TX test i will not cry for it.

  • Hi Remco,


    It look nice... interesting. For portable holiday operation helix feed not need even enclosure. What is the size of this dish? Did you test it for receive eshail beacons? How about influence between helix rf power radiaton and LNB safety?

  • The dish is (I believe) 64cm, but the effective surface is the width (will measure it later). I also receive the beacons with this setup, around 20 dB SNR (in 2500 Hz BW),

    so a little weaker than my other setup.


    I tested the setup a while ago while looking at BADR 4 with 11W @2400 MHz and found little degradation, in a sense that the noise floor 'danced' up and down for ca. 2 - 3 dB on my SSB signal.

  • I also use a 130cm dish for RX and 80cm for TX,


    The first reason is easy, if the TX dish is small then easily more RF power could be generated. (If you have the PA ;) )


    On the RX side it is complicated to get better reception.



    73 DB8TF

  • SP9VFD Raf I am just discussing with the company b.e.s.t. in Germany. They have rocket LNBs with PLL!!!

    If you disassemble the plastic enclosure the diameter will fit into the helix. Will get some information from them this week and will post it here. the most issue is to find a dish where the position of the LNB is more away from the boom as usual. for examle here a picture.

    With this it is easy to fit the reflektor for the helix. I have ordered a dish for less than 16Euro including S&H.

  • Why are you using the smaller dish for transmitting???

    We do not have a real operational experience yet. I will provide max 20W from the shack through Adrew CNT400 feeder 6m lenght. Including connectors and line losses, helix feed at focal point of 80cm offset dish will get more then 10w. According to official pre demands and requareiments it will be enough eirp. Maybe even to much more then necessery. In my opinion at this pre operational time more important is to have better reception. My choice 100cm dish for downlink will improve reception in hard weather conditions which sometimes we have in south mountains part of the Poland.

  • I am always interested in affordable PLL LNBs but I prefer the 4-port type so I can use one connector for reference input, and still have output for Ham Radio and for normal satellite usage.

    I have one here: SR-3604 or clone (unsure).

    I still need to convert it to external reference input. I'd like to find some solution so that it continues to work from the internal reference when no reference is supplied.

    (so I can watch TV with the reference turned off)

    I would be nice to have the datasheet of the chip (KTD1051 see http://www.ktdel.com/en/Product/Details/1653 ) but the manufacturer does not reply to mail, as seems usual in the far east.

  • pe1chl It looks like that the KTD1051 is similar to RT320 from RafaelMicro. I think you should find 2 chips inside because the SR-3604 is a Quad LNB. The dividing faktor shouls be 390 for low band and 424 for high band.

  • Yes, there are two of them, but there is only a single crystal between them.

    I would like to convert one half to external reference (1 connector for ref in and one for IF out) and the other half to remain on the crystal.

    My hypothesis is that the crystal is used with the oscillator in one of the chips, and the resulting signal (probably one pin of the crystal) is linked to the other chip.

    That is the connection I want to cut.

    But it would be helpful to know the local circuit for the crystal used in standalone mode and which pin is input and which is output.

    (usually the crystal oscillator in such chips takes the form of an amplifier to which the crystal is connected from output to input, and a capacitor on the input)