VX-4000v Data Jumpers: Nonexistent or optional?

[KS9X]

Picked up a few of these for APRS. Data to and from the D-Sub can either be 1200 or 9600; however I'm currently using an Easy-Digi which is neither meant for nor capable of 9600, and I'm not getting anything in or out. It won't trigger PTT and I'm not seeing anything other than myself on Xastir or YAAC. The service manual indicates that data I/O on the radio is switchable via a jumper at JP2006/JP2007 depending on which speed (it uses pins 13 and 17 regardless). There's a neighborhood of jumper locations from JP2002-JP2009 on the board but these are only solder pads. I only got a cursory look at the bottom of the board (truly, they don't make 'em like they used to) but can't find anything that stands out there e.g. pins/wires. Solder traces on the underside are a slim possibility but I couldn't get continuity between those two points and anything nearby that would make sense and not fry them. This is originally a VHF-C radio that didn't go below 148 MHz until I did the hex tweak to bring it down to 144; don't know if that's relevant.

• I can manually trigger PTT by shorting the appropriate pads on the side of the radio so I know that works.
• The rest of the signal chain is an RPi running the latest Direwolf with CM108 PTT functionality baked in, which talks through a CM108 USB fob. Direwolf CM108 PTT test program shows nothing wrong.*
• Direwolf config is basic iGate/Digipeater, not trying to reinvent the wheel.
• Direwolf is showing "Out" beacon messages and I will hear the data burst because the speaker is enabled--another thing I'm curious about which might be related--but neither Transmit nor Receive LEDs will come on (Receive will if squelch is off) and nothing breaks squelch at normal settings. Squelch is supposed to be off but I've experimented with various squelch settings in addition to that and unless I skipped one and didn't notice, it didn't have any effect.
• Antenna and feedline are all good end-to-end, quad-RG6 tuned-length to a vertical dipole and resonant at 144.390. Programmed other frequencies e.g. NOAA 162.525 and receive works fine.

What should be there if I want data out? And since nothing's there now, what should I jump JP2007 to in order to get data? Schematic didn't really tell me anything on this front.

*To the best of my knowledge, PTT in this current version does not require soldering anything to pin 13 to get GPIO 3 to work. I'm asking about this elsewhere just to be certain but haven't yet heard anything either way.

 

[tweiss3]

First, you should wire it for 9600, you can always run it at 1200 in direwolf.

Looking at the manual, it should have been wired as such
Pin 13 - Input to radio (TX)
Pin 11 - PTT
Pin 17 - Recieved output from radio (RX)
Pin 18 - Ground

For jumpers, jumper JP2006, it "should" be labeled on the board, but just be two solder pads. Bridge them with solder and it should make the the pins input & output start working. Without either jumper connected, nothing goes through pins 13/17.

As for getting the software to PTT, try in CE49 to change the PTT to invert and see if it keys.

 

[KS9X]

NOTE: It's been a busy week and I had this typed up yesterday morning but apparently didn't hit "Post Reply" hard enough. I've since gotten this sorted but I'm posting this anyway in case someone else needs the info to use the VXs for APRS with this setup; it's cheap and will probably become more prevalent.

While poking around various button-assignments and minutiae in CE-49, I discovered that PTT was already (or still) set to "inverted" thus torpedoing any other changes I might have made. Undoing that and assigning squelch control to the front panel so I could adjust it without having to keep going back into PC CLONE mode made a difference...

So, the Easy-Digi is set up to use the USB connection as basically a control line, and the data itself is at audio level going over dedicated send/receive 3.5mm cables. ***DO NOT USE AN UNPOWERED USB HUB FOR THIS*** or you're gonna have a bad time, especially with a Raspberry Pi. Use an externally-powered hub with the 5V taped off so there's no voltage feeding back in the wrong direction if you must, but a simple extension cable is the best idea, the shorter the better. The other side of this is that you're basically mixing line-level and mic-level I/O and it gets loud/noisy, to the point where Direwolf just doesn't hear anything but garbage. To that end, AGC needs to be turned off completely, and it's necessary to experiment with levels on the OS end.

Thanks tweiss3 for giving me the hints I needed to look at this from a different angle.

(Announcer): "PREVIOUSLY, ON 'THE VHF FILES'..."

First, you should wire it for 9600, you can always run it at 1200 in direwolf.

I thought about this but according to the service manual the difference on the radio end is the presence of filtering/limiting since, when set to 1200, it sends/receives in the audio range and 9600 does not. According to Clifford KF5INZ, the transformers in the Easy-Digi cut off at about 2700Hz; the range on the VX's data port at 1200 is 300-3000Hz so that's easily explained. It seems that the port is nominally capable of 9600 and adding the jumper engages a limiter. Since it's jumpered however, I get the impression the radio can do one or the other but can't downshift from 9600 to 1200 on the fly, because...

For jumpers, jumper JP2006, it "should" be labeled on the board, but just be two solder pads. Bridge them with solder and it should make the the pins input & output start working. Without either jumper connected, nothing goes through pins 13/17.

This is what I suspected as well but couldn't see what to jumper them to until I took a nice hi-res pic of the section of PCB where those points are located:

View attachment 114248

The flux/rosin/corrosion/whatever was there when I opened it (all 3 of the radios I bought have it somewhere) but more to the point, it appears the JP locations are jumpered to themselves: The solder bridges on 2005 and 2007 indicate this radio is already set up to do 1200. I'm an IT guy; I'm used to "jumper" meaning pins and a cap, or at the very least a solder bridge between two JP locations, not just one.

As for getting the software to PTT, try in CE49 to change the PTT to invert and see if it keys.

It didn't, but having it set to the default works wonders. I probably left it at "inverted" when I started running out of ideas. It got me to looking at the rest of the signal chain a bit differently however, so that works.

 

[tweiss3]

@KS9X Good deal. Good to know default PTT works. I have a pair of these sitting on the shelf that are going up for an upgrade to my iGate and adding a 9600 Winlink gateway.