TM-V71A sanity check before I cut ATT

[wh6ohm]

New Digirig Mobile user here. I’m trying this out instead of an older DRA card and believe I have everything set up correctly and I may need to cut the ATT connection as described on the site but I wanted to check here to make sure I have everything else set up correctly first.

My connections:
TM-V71A PC → Digirig Serial (green port)
TM-V71A Data → Digirig audio (9600 cable; black port)
USB-C → Windows 11 Laptop (COM3)
TM-V71A set to 9600 data speed

I tried testing via WSTJ-X and audio seems okay. I can control levels with Windows sliders and see changes.

When using VARA FM, I’m unable to connect to another station. Tuning with that station tells me that I need to adjust my audio. Here’s what everything looks like:

If I drop my recording level slider to “2”, it falls into the green VU range.

Additionally, my if I drag my playback device slider to 100, I “may” get an APPROVED stamp on the auto tune (-3db) but it seems hit or miss.

Can you offer any suggestions for an optimal configuration?

[K0TX]

In “custom” tab for Digirig’s recording device, do you have AGC unchecked?

[wh6ohm]

It is unchecked - I forgot to mention that one.

[K0TX]

If you are in low single digits for the recording device sensitivity and UV meter in Vara is still in the red, then activating attenuator should give you more adjustment range. You can always restore it with a solder blob if you decide to go back to non-attenuated input.

[wh6ohm]

Thank you. Any thoughts on the speaker audio levels not quite hitting the mark?

[K0TX]

With speaker output enabling attenuator makes sense because levels are much higher than line output from the accessory ports.

[TheDustyKey]

I am new to WinLink / VARA. Just sticking my oar in with what I know so far.

I have set up my V71 to use 9600 baud.

WH6OHM: “TM-V71A PC → Digirig Serial (green port)” - Not sure what you expect here. This cable doesn’t work at all as far as I know. See my other posts. It might work here, if the V71 doesn’t need to handshake with digirig for VARA. But it is not capable of handshaking with digirig 1.9.

TM-V71A Data → Digirig audio (9600 cable; black port)
TM-V71A set to 9600 data speed

digirig registers as COM8.

I built this adapter after seeing the huge signal levels from the V71. The L channel (Tip) has an inline 100K resistor. The other 3 channels are straight copper. I plug it into the digirig, and plug the cable into it. That way I don’t need to cut, solder, unsolder, resolder…etc.

** 1200 Baud (Pin 5 - PR1): Goes through standard radio audio processing, including pre-emphasis on transmit and de-emphasis on receive.
Expects lower I/O levels (around 40 mV p-p).
** 9600 Baud (Pin 4 - PR9): Bypasses the internal audio shaping (pre-emphasis/de-emphasis) and connects directly to the modulator/demodulator.
Expects a flat, higher-voltage input (often around 1-2 V p-p). 15 dB higher than 1200.

You can clearly see these levels in fldigi, because the 9600 levels will saturate (clip) the SIG display. I use the SIG display all the time to keep my fldigi RX audio p-p levels in recommended band.

I set up fldigi, which I am familiar with. I can trigger PT with fldigi and with VARA FM. I chose both NARROW (1200 bps, 1200 cable) and WIDE (9600bps, 9600 cable) in my VARA setup to test. I routinely use fldigi from my QTH, but have never connected to a VARA FM station from here. I am in a bit of a valley, and there are only 2 stations that I might hit, both questionable at any rate. So take all this as comment.

I see that you have digirig config as your Default Comm Device in the Sound dialog. I think it is recommended to run all these apps with digirig (SignaLInk, etc) config to be NEITHER Default Comm Device NOR Default Device, and let the app find the sound card in the table. You have done that I assume, though your VARA dialog is hidden by the Drive Level Cal dialog. With digirig config as Default Comm Device, it is susceptible to audio stream interference by Windows.

I don’t know if we are to select both L+R channels in VARA FM. digirig RX on L channel and TX on R channel, but all that might be handled by the time the signals leave digirig.

On 1200, 9600 I can trigger PTT on the V71. RX by another local radio and fldigi indicates good TX. On 9600, with the inline attenuator, VU meter is green. On 1200, without the inline attenuator, VU meter is green.

On 9600, if I tune the V71 to a NOAA station, I get fldigi SIG display in band. Closing fldigi (to release the COM port) and starting VARA FM, the VU meter clearly responds to NOAA transmissions, fluctuating in the green.

[TheDustyKey]

Update on using the V71 9600 port with the inline attenuator. I realize these notes are a) brief and techy, and 2) targeted toward V71 users. Ignore the strange formatting. It’s all just plain text.

20260314 test: “levels” are Windows Sound levels. fldigi BPSK125. Waterfall=500 Hz. W1(0|1)=Windows 1(0|1).
SignaLink pots: TX=mid, RX=mid, Delay=10%.
TX W11 F6A+SL levels=-10 dB > W10 V71A+digirig 1.9 @9600 w inline 20 dB att levels=+3 dB
Tune OK.
Send beacon: OK, but SL needs small DELAY to avoid dropping TX when fldigi goes silent during TX stream.
When TX includes TxID, RX stream also gets “noise” preamble and postamble, in addition to full copy.

TX W10 V71A+digirig 1.9 @9600 levels=+0 dB > W11 F6A+SL VOL=09:00 levels=+5 dB (SIG 100%)
Tune OK.
Send beacon: RX SIG 100%. Same comment. TxID adds junk to RX panel text.

TX W10 F6A+SL levels=-10 dB > W10 V71A+SL @9600 levels=+3 dB
Tune OK.
Send beacon: SIG 100%. Same comment. TxID adds junk to RX panel text.
***** Important note:
Initial testing TX W10 V71+SL > W11 F6+SL.
It seems that V71 audio is present simultaneously on Pin 5:PR1:40 mV p-p and Pin 4:PR9:2 V p-p.
The V71 uses one of these for transmission, depending on the setting of #518:DATSPD.
DATSPD can be changed without cycling V71 power (PC baud rate needs power cycle).
When I used SL jumpered for 1200, with the V71:#518:DATSPD:9600, the RX SIG was ~10% FS.
When I changed to V71:#518:DATSPD:1200, RX SIG was ~105% FS, which I reduced to 100% with the F6 VOL.
When I changed the SL jumper to 9600, the RX SIG was still 100%. (#518:DATSPD:1200)
When I changed to #518:DATSPD:9600, the RX SIG was 120%, which I reduced with F6 VOL.
When I changed to #518:DATSPD:1200, the RX SIG OFF scale HI, which I reduced with F6 VOL=08:00.
I returned the V71 to #518:DATSPD:9600, F6 VOL=12:00.
TX W11 F6 > W10 V71 (#518:DATSPD:9600, SL jumpered 9600). Acceptable SIG level. Slight DC offset, seen in other HT transmissions.
*** Leaving the V71 in 9600 (raw audio) results in a very *** noisy no-signal spectrum ***.
*** fldigi SIG is over 100%. fldigi FFT shows broad spectrum half way up the vertical axis.
When a signal is present, the V71 sends a clean signal to the computer. SIG and FFT immediately show expected clean signals.

Summary: 9600 works as well as 1200, using the home-built inline attenuator. I suspect it will work with the Lite, too. I have one, and will be testing that so I know. The 9600 audio is noisier, but quiets right down once a signal is RX. We still need to be skilled as operators to properly adjust our radios, Windows sound drivers, and fldigi to obtain the best audio stream. I opine the underused fldigi SIG display is your friend.

[wh6ohm]

WH6OHM: “TM-V71A PC → Digirig Serial (green port)” - Not sure what you expect here. This cable doesn’t work at all as far as I know.

I guess I’m confused then because that’s the set of cables for the V71 (https://digirig.net/product/kenwood-tm-v71a-cables/). Are you saying for my application (VARA) I only need the data cable?

Using fldigi to test is a great idea and I will check the other settings you mentioned, thank you. I was able to get much better signal after cutting the ATT jumper.

[TheDustyKey]

I apologize for the delay…/grin/ I remember writing and mailing letters !

I have not found the digirig “green” cable for the TM-V71 to work under any circumstance. So you might as well tuck it in a drawer.

Now for VARA. Yes, just the audio/PTT cable will work with VARA for 1200 and 9600 baud ports.

I didna cut the ATT jumper, but I did make the adapter above.

Unlicensed VARA transmissions are limited to 1200 bps. If you fork over the license fee, you can reach a very respectable TRX rate using the 1200 baud port. True, you will reach a higher speed on 9600. But I have yet to find anyone local…or anyone not just testing VARA FM…who needs the increased speed. I was headed that way until I did my tests, and now I will stick with the 1200 port until a need arises for the higher speed. I also decided not to buy a license until I see that there are sufficient nodes for me to TRX with. Even at that, VARA on HF is likely to be more useful to me here, and that might prompt me to buy a license. Curiously, a web search for the place to buy a license came up empty. (Yes, I know of the link in the app.)

So I returned all my gear to the 1200 setting, and retested all the audio stream settings so that I have current values that I know deliver undistorted audio. (My testing showed that the Kenwood F6 distorted audio as audio level increased. I used the Sound dialog to lower the output as I monitored the transmission on another system. The Tune tone had some distortion and a DC offset. Reducing the audio into the F6 mic removed the DC offset and distortion.)

Speaking of cables, I have not found any software that uses the green cable that comes with the digirig set for Kenwood HTs. I’m tossing that with the other one into a drawer.