Posts by OM3BD

    The software uses 4800 baud default CAT rate. The USB port you can set under Setup/Hardware/Transmitter.

    Thank you for the reply, Frank.

    I've set the CAT rate to 4800 and set the Hardware/Transmitter to the correct USB port, but it is still not working. I've double checked all connections and believe they are correct:

    TX D pin to RXD on USB/TTL converter, RX D to TXD, TX GND to CTS, GND to GND.

    I must be doing something wrong, any suggestions?

    73, Bill

    In this version you can also use CTS. But it is a very very old version. I recommend to use Raspberry Pi 4B with last satcontrol software. There are many changes and improvements.

    Yes, perhaps soon I will buy a Raspberry 4, but for now I just have 3B.

    I made a cable from the DIN plug to the USB/TTL converter and connected everything as described. I set the CAT rate on the FT817 to 38,400. But it does not seem to be working, the program is not controlling the FT817. There is a red LED illuminated on the USB/TTL board.

    Are there some other settings I need to configure? I've never used a Raspberry before, but I know that on a Windows PC it is necessary to set the port, baud rate, etc., to make the CAT work.

    73, Bill


    I am operating successfully using a Raspberry and gqrx but would like to try SDR Console on Windows 10 laptop, using RTL-SDR hardware and SDR console 3.0.25.

    Following the instructions at, I think I have set up SDR Console correctly, and I am seeing signals from QO-100. I was just wondering if it is possible to see the band plan on SDR Console, as with gqrx. The band plan on the screen is quite helpful.

    Thanks and 73,

    Bill OM3BD

    Hi Bill,

    test it with your H155, i think it will be ok.

    Good luck

    73 Wilhelm

    Wilhelm, you are correct. I used an SMA to SMA-R adapter on the end of the 10m H155 coax, and now all is working fine. I have moved the shack inside and am very happy. Later I will replace the BamaTech on the new dish with the POTY/LNB combination, so that only one dish will be needed.

    Thanks to everyone who replied and helped me with this project! Hope to have a QSO with you on QO-100!

    73, Bill

    Hi Bill,

    the attenuation of your H155 is about 5db @2400 MHz and i guess the N Connector is a cheap part from LingLing (here for cheap chinese goods). So you only have 1/4 of the power on the feed. The H155 is not usable for 2400 MHz. The RL is only 15db @2400 MHz (SWR 1,43) Look at datasheet from Belden.

    73, Frank


    I knew about the 5db+ attenuation from the coax but did not consider the connectors, thank you for reminding me of those. I thought that a 6db loss would not be a problem, as it would give me 10w at the antenna, more than enough for QO-100. My friend also has 20w and the same 10m H155 cable and he has more than enough power.

    Thanks to Wilhelm I just learned that my main problem was that the my has an SMA-R connector. When this is fixed I'll try again and report the results. I'm not sure there is any coax better than H155 available here in Slovakia. If it is too lossy I'll have to order something online. What would you recommend? I've heard that RF240 is a bit better than H155.

    73, Bill

    It looks well made. A ruler will not be accurate enough. Do you have a 3mm drill bit for example?

    It looks like the problem is coax or connector, not the POTY.

    The POTY has an N connector, the Bamatech has an SMA. I have a 10m length of H155 with an N connector and a 0.5 length with an SMA. So I used the 0.5m with the Bamatech and it worked, strong signal on downlink, swr good. I used the 10m with the POTY and no success, could not hear my signal on downlink, high swr.

    Today I got an N to SMA adaptor and for the first time was able to try the 10m coax with the Bamatech feed. And the result was the same as with the POTY - nothing on downlink, high swr. This was quite a surprise because the 10m coax appears to be high quality Belden with professionally installed connectors. I'll have to find another coax and hope that works. I thought perhaps 10m was too long and lossy but my friend also has 20w PA and 10m of H155, and his signal is so loud he has to reduce power to avoid Laila.

    Anyhow, I'll try the POTY on a fresh coax and hopefully have success without having to resolder or bend.

    In the meantime, I am FINALLY qrv on QO-100 using the Bamatech feed and the 80cm dish for TX, and a second dish with just the LNB for RX. But since for now I just have it working with the 0.5m coax, I must bring the radio outside and sit next to the dish to operate. I had several nice QSOs today with good reports. But it will be better when I can sit inside in the nice warm shack.

    73, Bill

    Hi Bill

    The POTY spacing and dimensions are critical for it to work. 4mm spacing is a 25% error so far to far out. I would suggest re-soldering it with a temporary 3mm spacer to get it correct. Then you might need to bend a little to get best match. Starting from 4mm spacing would not be good. Perhaps you can show a more detailed image ? The critical spacing is the gap between the plates but also the way the connector is mounted matters. There should be no screws coming into the gap.



    Here are a few more photos. The prior owner says this POTY has been tuned and tested. I measured just under 4mm with a ruler, I don't have calipers, the measurement could be off. Also, the only available coax I have to connect the PA output to the POTY is a 10m length of H155, that probably loses half my output.

    I just tried the BamaTech feed again and it is still working, I see my downlink and swr is low.

    Select a display BW of at least 3 MHz and you should see a hump about 600 kHz wide and 3-4 dB sticking out of the noise floor left and right. This is the transponder passband and the 'stick out' value is the only one which is independent of the SDR software used.

    Yes, I am seeing the hump and signals are strong. Looks like the rx side of my setup is good.




    POTY high SWR?

    It finally stopped raining so I brought the radio outside and repaired the dish, which was not damaged. By fine tuning the azimuth and elevation, I was able to get better signals on rx, -35 on the beacon on the gqrx dBFS meter with just the LNB, -38 with the LNB mounted on the POTY (no lens). Is that about normal? I'm familiar with the dBm S meter scale on the web SDR but I've never before seen a meter with a "dBFS" scale.

    Anyhow, I was happy until I tried to transmit. I did not see my signal on the downlink. I opened the amp and I'm reading 0.34v on DRV, 3.3v FWD, 2.3v on REF. So it seems the SWR is too high. There was only 0.1v on REF with the BamaTech feed. So it seems there is an issue with the POTY. Is it possible to adjust it for lower SWR? And what are the mechanical tolerances? I see on the instructions that there is supposed to be 3mm between the reflector and the DE, on mine it is closer to 4mm, is that a problem. I'm also not sure the two pieces of metal are 100% parallel to each other.

    Thanks for any advice and 73,


    The simple way to fix the height change to grab one side of the mount firmly with one hand, the end of the boom with the other and bend the boom to the right spot. Most LNB supports for inexpensive dishes are suitably flexible to do this.


    Thanks, Mike. It has been raining non-stop for 2 days, if it would just stop raining for 30 minutes, I could take the radio outside and watch the meter for best reception as I adjust the dish.

    Yes, :thumbup:

    to lengthen is the better idea, and you have more place/distance with the POTY reflector disk to the feed arm.

    You have also a wider area to slide the POTY in direction to the dish reflector to find the best position for focus.

    Here is what I came up with last night. With this setup, I could hear the beacon and some QSOs, but signals were weak. On TX, I could not see my signal on the waterfall. So more work needed.

    My guess is that the problem is the position of the feed. The feed is now the same distance from the feed as it was in the original, where it was working well, but in the original the bottom of the reflector was touching the mount, now it is about 2 cm above, so it is not pointing to the same spot on the dish. Any way to fix this?

    73, Bill

    Ok, I see

    You can try do make a wooden or plastic 40 / 22mm excentric adapter.

    If you place the excentric exakt vertikal you only have to adjust the elevation of your dish.

    Mabye then is on the upper side of the holder enogh place for the N-Connector.

    Very clever! But even with no adapter, the female N connector barely passes. The male connector would not pass. Could I extend the arm so that the mount/adapter attaches lower on the POTY, away from the N connector, as in the drawing below?