iw5bsf Hi Roberto, I measure my directional coupler and it is suitable for 1.2 GHz and 2.4 GHz only. In 5GHz it has hi SWR. In 5&10 GHz there is no difference between coupling and directivity. I was blind and happy with my directional coupler ...
Posts by SV1BDS
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Hi, it seems OK now ...
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PA3FYM Hello Remco, this is my SWR plot of my POTY feeder. I do not see the second null near 2.4 GHz. Any comments ?
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Hi,
I have mesured the V PtoP at UHF 1 W and it was about 300 mV. I replaced them with BAT85 and it was about the same.The danger is that if PTT line is disconnected you will burn the circuit ...Nice ideas about mixers. I used MAX2671. PCB is available. I measured 50 dB down two tone test at -22 dBm output.A nice solution is also ADE25MH but it is not found cheap at eBay any more .... SV9RYG have you think to go to an SDR solution like Pluto ?What solution do you think about GPSDO ? Have you seen the Lars GPSDO? It is easy to get 25 MHz from it for ADF4350/1 and LNB.Any way how do you think to get 25 MHz from GPSDO? It is a critical point and some solutions does not work !!!
I hope good results in your exams !!!
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A good proposal for TR switch without relays is link.
What mixer are you plan to use for Tx (HCD)?
Why you use split operation mode - I think there is no reason as you operate half duplex?
You can use also ADF4350 which is cheeper.
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Dear om:
If it is possible, please, send the grc code for work with it?
My email is: petorrin@euskalnet.net
73,s de Jabi, ea2aru.
Also to sv1bds at yahoo dot com if possible.
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Hi, my proposal is to try triangle matching like Link. I have try both and triangle is better.
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Hi,
The only point that is under investigation is if available 2.4 GHz filters are drop image from 70 MHz IF from your 7300. Also ADF4350 can be used that costs less. In your block diagram you mention 100 MHz GPSDO but usually are 10 MHz. ADF4350,1 require 25 MHz that are required also for LNB if drived externally. A GPSDO can be build with Arduino using Lars design.
UPD: The filter I use is not suitable . LINK this it seems OK.
UPD2: see also this LINK
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Hi,
Just for the history my first QO100 transmission was with a laptop controlling a ADF4351 at 2.4 GHz , two amplifiers producing 3W and a homebrew helix powered from two lead acid batteries !!!
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Geia soy
Have a look here : LINK
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Hi,
A 50 bps test at QO100.
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OE3GBB Hi Gerhard, I have not yet succesfully send CODEC2 data via DQPSK or even QPSK, even locally. I noticed that they use 15 (14+1) carriers instead of one that I trying. Is QO100 phase noise so high that it does not permit to use one high speed carrier ? It has been tested one high speed carrier in QO100?
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OE3GBB I found the reason for increased BW, the data was unpacked and I treated as packed so I reduce BW by 8 !!! Now for codec2 is 1.8 KHz BW. I test it with loopback successfully but in QO100 it doesn't work. In loopback it is a lot of dB more sensitive.
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OE3GBB I build codec2 & gsm local tranceiver (50 dB attenuation at Pluto) using OFDM gnuradio building blocks. The bw was 15 & 25 KHz. It was working with 10 dB SNR. There a lot of work to reach 1.5 KHz of freedv... There are used about 25 gnuradio blocks. I use BPSK for headers and QPSK for payload. I was not loose voice even with 1 KHz frequency drift !!!
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Hi,
I try to reduce output power with no success. I try to reduce drive to the Pluto and it was successfull !! The possible reason is the overdrive of internal Pluto mixer and not of the final amplifier.
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SV1BDS George I am using the SF2124e SAW filter at the PLUTO out.
I test it at 430 MHz. Anyway why a filter will improve IMD of two 1 KHz tones?
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Try to reduce the Pluto output power by at least 10 dB from full scale. This should improve a bit..
I will try it.
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Hi,
It has been noticed spurious transmitions left and right from Pluto using GNURadio and SDRConsole. I try to do at dummy load tests using OFDM & GNURadio. I notice spurious about 10 dB down left and right. So I create a simple GRC for two tone test. It seems that the firsts IMD products are less than 20 dB down !!!
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Hi,
Testing 8PSK local with an SNR similar to QO100 and real to satellite. 18-53 is localy and 38-56 via QO100.