You will find the need to adjust the gain to a very low level as the the ourput from your radio will be much hotter than the mic input on the soundcard is expecting…but there is enough adjustment to makeit work
When I ran an IGate using an SDR dongle, I noticed a qualitative improvement by adding a bandpass filter for 2 meters. I made this one, maybe not suitable for transmitting, but there are also readymade commercial versions, SOTABeams for example.
3 Likes
Thanks WN3F I will take a look.
Ordered the USB sound card.
Goodluck.
The direwolf manual also contains the schematic for using a 555 timer as a watchdog on tx, combined with a level shift from the 12v on your radio to the lower voltage on the R Pi. So it is a relatively straightforward step to produce a digipeater (which of course would require an NOV to your license). Toying with the idea of setting up a digipeater myself.
Some years ago I made a portable APRS iGate that I use when I am on SOTA activations. Here is the reflector thread I wrote back then:
The iGate is still working fine …
73 Martin, OE5REO
2 Likes
I am operating an RX-only APRS iGate on a Pi3 with a (bit better) SDR dongle. As a frontend filter, I am currently just using an 88-108 MHz trap for the FM radio band. RX performance is okay but not great. If time permits, I will replace the SDR by a spare Baofeng or add a narrow 2m bandpass. As the SDR dongles are just 8 bit if I am correct, a barn-wide frontend will hence not work very well.
1 Like
I’m running a Pi2B with a pair of Nesdr Smart v4 - one is used for an APRS IGate, the other as an ADS-B receiver.
Both work OK, but the APRS one doesn’t recieve and decode as many packets as the IC9700 (not surprising) but it’s about 1/50th of the price. It picked me up no problem this evening on GW/NW-062 even though nobody seemed to be able to hear me 
Hi John,
I have been running an I-gate in the past. Gave up when I needed the radio for other purposes.
I would improve your set-up with a dedicated 2m FM radio. Even an older model picked up at a hamfest would likely do better than a (super broad) SDR dongle. Next thing to improve would be the antenna. Try to get ot out of the attic if circumstances allow.
73 Heinz
2 Likes
I am playing with an old FT-470 into a RPI 3. Technically it works, but I need to find a way of using a decent antenna outside so I can do some more tests. I also used the K5EOK notes as a starter. I have really only tried it as an igate rather than a digipeater. I also managed to set it up with an FT-817 which worked on tx as well as rx. Probably spent as long faffing around getting the Remote Desktop working as dealing with the radio bits… Paul
I had one of those when 1st licenced in 1990. It was awful with an external antenna on 2m. 70cms was fine but 2m was terribly for overload etc. It needs a filter of some sort to make it OK.
1 Like
I do have an external discone antenna which I could use but this is currently connected to my Icom IC-R7000. I would need to find a method of splitting aerial to two radios (other than splitting the coax)/Using a coax T-Piece,
Use the Icom R7000 temporarily on the I-Gate to see if this cures deafness! This would probably need some cables/adapters to be configured. You could later replace it with a cheaper radio for APRS use.
I did think that but until I get the USB sound card I don’t think the Pi will take the audio input directly?
It did need an external sound card. I ended up faffing around for ages with the software thinking it was an awkward driver issue…it was the audio cable…
2 Likes
Amazon have the sound card in their van and destined for me 
While awaiting the delivery and the time to build a new Pi config. I decided to do some testing.
Swapped the loft based aerial for the external discone antenna to feed the Pi/SDR.
Used the loft based antenna to feed the Icom.
On a laptop running AFSK1200 Decoder I connected the laptop to the Icom via an audio cable and using the FT3D went for a walk.
The laptop/Icom picked up the data bursts every 10mins as configured on the FT3D.
The Pi/SDR only picked me up at home at the start and at the finish back home.
I noticed that I picked up G7NIR-7 who was mobile in North Wales on the Icom/Laptop combo.
I will repeat the same test once the Pi is rebuilt to see how the results compare.
Good news. The USB sound card arrived and after a bit head scratching, I sussed the direwolf.conf file had been returned to default so I needed to setup again.
A quick test from the window ledge, the FT3D - m0vaz-7 is back sending APRS packets
Cheers all.
I’ve never quite found the time to experiment but thought the Dorji modules (with the right filtering etc) might make a suitable low cost solution. SV1AFN does one.
I think the module is in a few cheapo handhelds.
Wondered if there was any experience with them as either an igate or digipeater?
1 Like
Hi Alex
Thanks for the link to the VHF transceiver.
It might be a candidate for an Igate/Digipeater.
Currently hooked up to yet another scanner - this time a Uniden Bearcat (saves leaving the R7000 powered up)
I do have a spare Motorola GP300 VHF handheld that I think has no TX - this could be another option.