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FT 990 IF output

Posted: Thu Aug 23, 2018 8:07 pm
by Maerli
Hi folks
How I can connect the SDRplay with my FT990 and the MFJ 1708 SDR?
I have an IF output port (female RCA ) in the back of the radio

Thanks in advance
Mario
PY2DV

Re: FT 990 IF output

Posted: Fri Aug 24, 2018 10:22 am
by DK7OB
Is your FT-990 modified? We have an FT-990 at our club station and it has no IF output.

Regards,
Wolf, DK7OB

Re: FT 990 IF output

Posted: Fri Aug 24, 2018 12:18 pm
by Maerli
Wolf
Yes, its modified...I want to know if I need the mfj 1708 , or only the sdrplay...

Re: FT 990 IF output

Posted: Sat Aug 25, 2018 11:37 am
by DK7OB
I just looked up the mfj 1708. It is a T/R switch.

You don't need it as you want to connect your SDRPlay to the IF output and not the antenna.

Re: FT 990 IF output

Posted: Mon Oct 01, 2018 8:30 am
by g4jnw
Just out of interest how did you take the IF out of your FT990 and whats the difference between using the RX out thats already on the FT990?

Re: FT 990 IF output

Posted: Wed Oct 03, 2018 7:36 am
by DK7OB
I you want to use the RX out, you need a splitter because the RX ANT button on the FT990 simply opens the connection from T/R relay RX side to receiver input and makes them available as RX out resp. RX in externally. I use a Micro Circuits PSC-2-1 for this. This gives a 3dB loss, but that does not matter on HF.

Re: FT 990 IF output

Posted: Wed Oct 03, 2018 9:12 am
by g4jnw
ok if i use an Micro Circuits PSC-2-1 or similar (can't see them in the UK) where does the Micro Circuits PSC-2-1 go?

At the moment ive had my longwire into the so239 and a wellbrook loop into the rx in and the sdrplay into rx out, i get better results when putting the antennas straight into the sdrplay.

Re: FT 990 IF output

Posted: Wed Oct 03, 2018 5:01 pm
by Roger
g4jnw wrote:ok if i use an Micro Circuits PSC-2-1 or similar (can't see them in the UK) where does the Micro Circuits PSC-2-1 go?
Diamond makes a nice splitter and they are available in the UK from ham shops. I just did some tests on a good quality CATV splitter that was rated from 5 to 1000 Mhz. It worked quite well down to the 80M band. About 3.5 db loss and 20 db isolation between output ports. A cheaper alternative but make sure you get the type the CATV companies use not the cheap consumer units. Here is how you hook it up.
SPLITTER SDRPLAY2.png
SPLITTER SDRPLAY2.png (177.63 KiB) Viewed 5742 times

Re: FT 990 IF output

Posted: Thu Oct 04, 2018 12:19 pm
by g4jnw
Thanks have ordered the diamond splitter as in the diagram, i trust diamond so worth paying the extra. Thanks again

Re: FT 990 IF output

Posted: Thu May 09, 2019 8:05 pm
by D.C. Alden
I found this post very interesting. I also have a Yaesu FT-990 that I would like to interface with my RSP2. This seems like a simple way but I have a few questions.

What exactly is coming out of the RX Output connection? Is it a direct connection to the main antenna input or a signal from the receiver?

Does the splitter split the signal and then pipe it back into BOTH the RSP and the transceiver? In other words, are both receivers still functional?

It would be nice to have the option of turning down the volume on the transceiver and listening through the RSP or turning down the volume on the RSP and listening through the transceiver.

Most importantly, does this setup provide enough isolation for the RSP so that it is not damaged if I transmit with up to 100 watts? Does this eliminate the need to use something like the MFJ-1708SDR? Can I leave my vhf-uhf antenna hooked up to the RSP while transmitting (Asuuming a reasonable separation between the vhf-uhf antenna and the hf antenna)?

Are there any internal mods needed on the FT-990 or special settings on the front panel?

It’s an exciting prospect to be able to augment the very capable FT-990 with modern digital features!