Posts by PA1EW

    Tnx Heiner!. I am very happy with the setup. As expected the Kuhne MKU upconverter is perfect for this purpose and the Helix-dualfeed does also a good job. There is a RF-splitter in the box that will be used to connect to a SDRplay RSP2, but not used here to keep the setup simple as can be seen.

    Hope to work you and many others during my upcoming vacation when I will take the portable station along.

    73 Ed

    First field test at a demonstration last Friday at our VERON Maastricht Radio Club with the portable QO-100 full-duplex setup was very succesful.

    Initially tuned the 70cm RX to 435,800MHz (EB-frequency 10489,800MHz) and the beacon could soon be received with a clear and strong signal.

    Clear view to the sat with 20W from the MKU2424A into the 60cm offset dish producing respectable Up/Downlink signals. Even just on battery-power!.

    Fellow HAMs were surprised about the very good quality, like a local repeater hi,hi.

    73 Ed PA1EW/P

    i2NDT Hello Claudio. The (very old) box is made out of a lightweight "plastic" and was available many years ago at a local electronics shop. I am not sure if this still can be found.It was unused by me for a long time, but now I finally found a good use for it...!.

    It measures 22 x 22 x 31cm.

    73 Ed

    DD0KP Hello Heiner, Looks like a great solution!. Though, I am curious about possible extra attenuation to the 2.4GHz patch radiator from the PVC material?. I recall reading some negative reports about PVC for this use.

    When possible, please tell us what you measure without- and with this PVC cap.


    73 Ed

    A75GR Hmmm..., I was already wondering about heating up with transparant covers and so it seems to be a real challenge with these temperatures 8)

    Good luck with the protective cover as you describe.

    Anyway, it is an impressive construction that will give good signals over QO-100!.

    73, Ed PA1EW

    df2et Hi Florian, well done!. The new installed reference input connector looks really good.

    I did not open-up my modified converter yet, but thanks to your clear pictures I can see how the two side halves are separated. So, only unscrewing the 2 lower frontpanel + 2 backpanel screws will make the sides to separate, I guess?.

    Anyway, I am very happy with the modification as the standard stability, without external reference, seems sufficient for most work. Hope that Kuhne will provide soon some information about this extra feature. I will probably make use of it later.

    73 Ed PA1EW

    I want to present my design for a single-dish portable station as described below and partly shown in the pictures. For me it should meet the following requirements:

    ·       Easily detachable construction (transport by car)

    ·       Single offset dish 60cm, dual band feed

    ·       Stable tripod mounting

    ·       Comfortable adjustment of dish heading

    ·       Compact “radio-box” to carry two full-duplex transceivers + SDR

    ·       12V operation (battery) possibility

    A new adapter bracket (picture 1) was constructed to mount the Triax 64 dish in a stable way to the tripod pan-tilt head. The dish's own (elevation)adjustment is fixed and not used. Another bracket (left side in picture 4) is added to carry the plastic box with Mini-GPSDO 27,841846MHz + 30MHz low-pass filter + battery pack 5V.

    As my modified Octagon LNB was readily available to be combined with the 5,25 turns LHCP Helix, I choose this for the moment above the patch-feed to be used as dual feed. The Helix/LNB mounting has been improved from the quick-and-dirty tape-construction to the detachable- and adjustable Helix-reflector mounting as shown in picture 2 & 3.

    The construction allows also for LNB skew-adjustment rotation at any time. Releasing the two wingnuts (pictures 2 & 3) on the sides will then allow for LNB –focus adjustment, the Helix reflector is moved too. The Helix reflector is held in place also by the front-section of the Octagon LNB.

    Last item to be finished is a compact housing for the FT817 (144MHz TX driver) and a TM-455E (435MHz RX). The modified MKU2424A (=B) up-converter will be placed on top. A compact 13.8VDC/22A SMPS supplies the power when 230VAC is available, when not, a 12V gel-battery could be used. Hook-up for SDRplay RSP2 is also foreseen. Hope to work you soon via QO-100 with this portable station!.

    I am curious who has similar- or totally different portable constructions, please let us know and show.

    73 Ed PA1EW/P

    om0aao Hi Viliam, when looking at the middle photo with the assembled patch, I can add two more things that possibly affect performance:

    • grounding contact of the N-connector body. It seems to be on "stand-offs" and would be better when attached over a large contact-area
    • the black isolating/support (material?) in between the radiator and reflector may cause degradation. Small Teflon bushings would be better perhaps.

    73 Ed

    So, today I managed to test and compare the dualband-patch antenna in the same 60cm offset dish.

    The patch radiator was placed in focus, like where the Octagon LNB was before. I compared, one after the other, the results from the previously shown dualband helix-LNB with the patch-feed and found for both systems similar signal-levels from my uplinked signal. Only a difference of abt 0.5dB for maximum signals with each feed. Measured SWR of the patch in the focal point a bit under 1.3, so that's fine.

    (Pictures of patch-feed were taken after the test setup was removed)

    73 Ed

    My Kuhne up-converter 2424A was returned this week after succesfull modification. I made some contacts that showed improved stability, even with the higher power-levels.

    So, now i could start testing my dual-band helix feed, together with a portable setup with 60cm offset dish on a tripod. Everything experimental and only practical tests done today.

    Several parts are re-used from the home-station. Downlink (Octagon LNB with mini-GPSDO and IF 435MHz ) was first set up and dish heading optimized. Using temporarily RTL-SDR for this test.

    Last test was TX Uplink-only (RX via Amsat-UK webSDR) with the combined dual-feed at a power level of abt 10-12W ( estimated 10W at the feed). FT817 used for driving the upconverter. First results showed strong uplink of some dB above the FSK-beacon, so a nice signal. Real measurements still to be done but this seems to work OK for portable use, as intended.

    Checking the up-and downlink combined (full-duplex) will follow after finishing the (compact) portable equipment construction that will serve demonstration purposes as well. My dualband patch-feed is also waiting to be tested. Hope the weather stays OK...

    73 Ed

    Very nice!. Perhaps you can consider, instead of the bag, using a suitable transparant cilinder (PE-PP) with top-cap slid over the whole dual band feed and leaving the under-side open. With this in place you are still able to view the beautifull internals and avoid condensation being built-up.

    73 Ed

    Did anyone test the new performance of a modified 2424 A, without using the external reference?. I am curious if one can use up to full power without degradation by "FM-ing".

    My unit is to arrive tomorrow and can't wait to have it back..

    73 Ed

    DD0KP Thanks Heiner, I am very curious how my patch will perform. Once I have the Kuhne up-converter back I can start testing ( and getting back on-air!).

    I think when your helix was properly built it should work as good as the patch. Anyway, whishing you good luck with the new patch-feed!. I now can see some pro's and con's and some depending on preference as well.

    73 Ed

    G0MJW Yes, it is silvered indeed. Just a very thin layer applied with rubb-on chemical process from a bottle with (toxic!) liquid containing silver. I used this also on my helix copper wires. It is more for the "looks" and perhaps does a good job regarding skin-effects.

    73 Ed