https://digirig.net/category/tips-tricks/

Have the DELCO folks read as much as they can stand to read on the DIGIRIG site.

It has lots of good information about audio in general, PTT in general, and audio cables.

Thank you for allowing me to evesdrop on last night’s DELCO meeting at Lima.

Here are a few quick observations.

Always be sure your antenna is not close to your sound card/computer.

Radio interference into the sound card cables is a major source of headaches.

I think last night the mag mount antennas were too close to the computers/sound cards.

Check to be sure that Windows (10/11) is “allowing” you to use the MIC device that represents your sound card. Windows “PRIVACY” issues are common and hard to find and change. Especially Win 11 setup.

Never turn on any “advanced” sound control settings that Windows suggests. These are often a signal processing algorithm that Windows engineers like - sort of similar to the noise “reduction” button on HF SSB radios.

And never never turn on AGC option under LEVELS.

I would always put toroid  filters on both ends of all audio cables and usb cables, to help prevent RFI (radio interference).

Here are some particulars I saw based on the radios DELCO has

On any radio that does not have a dedicated DATA socket, which is the Icom 4100 and 5100 you have to be very careful with the audio cables. First, your receive audio must be taken from the rear EXTERNAL SPEAKER (3.5mm) socket.  On some radios this is MONO but on some radios a sterero 3 conductor plug will still work. Now speaker audio can be 500 mV to 1000 mV output depending on where you turn up your VOL knob on the radio. That is way way too much audio for a sound card MIC input (50 mV). So first, unsquelch the radio (never turn on squelch) and just nudge the volume up a bit. Or, better yet, use a Y-splitter (Nadine had one) and connect one side to a real external speaker or headphone, and the other side to the sound card MIC input. That way you can hear the RX audio, if you so choose.

The Digirig has NO KNOBS -  to keep it small and cheap ($60).

So, unlike most other larger sound cards, there are no RX level volume knobs.

You likely will feed in too much receive audio into the MIC input on the Digirig if you have the audio coming from a EXT Speaker jack - but you may not have any options if there is no dedicated DATA socket.

HOWEVER, inside the Digirig, there is a small circuit board that you must alter.

Read the directions with every Digirig Mobile device.

There is a circuit that says ATT (attenuation for receive audio). It is your only hope to get the proper amount of receive audio into the MIC input on the sound chip.

The Digirig manual says to CAREFULLY cut the ATT trace on the circuit board with a sharp knife - gently. After a few light cuts, you OPEN the jumper, and now there is a high resistance resistor in the RX audio path circuit (maybe 100,000 ohms) which will reduce the receive audio level by 20 dB.

I had to do that on both of my Digirig Mobile devices.

Too bad these Digirigs do not come with an ATT plug.

Once you do that, you will have a 20 dB ATTENUATION of receive audio. It does not affect your transmit audio - only receive audio.

Now, the next thing you want to do is to get into the Windows Sound Control Panel (any way you can) and go to SOUNDS, and select the Digirig PNP audio codec, and select RECORDING tab.  Uncheck the AGC option (never never turn on AGC).

Then go to the LEVELS for MICROPHONE and select the lowest level - 0 dB.

That means “no gain” but the gain is fine. You can add up to +23dB gain by sliding the level slider to the right. It may read in percent rather than in dB.

Right click to change the labels - dB or %.  You want 0% gain or 0% level.

That can always be readjusted later on.

Now, with audio coming from an EXT SPEAKER jack (few hundred mV) you can select the amount of receive audio with the Windows RECORDING tab so that the VU meter in VARA FM reads about 2 O’clock (-10 to -20 dB) with background noise on any unused FM frequency.

Now - watch out. This is important.

When you get receive audio from a SPEAKER jack, you can NOT select 9600 baud on any MENU item in the radio. Although these BAUD terms originated with 1200 baud and 9600 baud PACKET signals, the MENU items may still refer to PACKET speeds. Always choose the 1200 baud “speed” - even if you are using VARA FM and not PACKET sounds.

That implies when you open the VARA FM modem, always choose the “NARROW” mode and not VARA WIDE.

OK so far?

Now, the tough one - transmit audio and PTT.

For PTT, with a Digirig, you MUST choose to send via a +voltage sent on the RTS pin.

That is the only option.

RTS is just a particular pin on a serial port. Inside the Digirig, it can detect the RTS pin and when it sees a + voltage, it trips a relay or transistor switch inside the Digirig, which closes the PTT circuit ==> the radio goes into transmit mode.

In other words, a COM port controlled by your software (VARA FM) will change your radio from receive mode to transmit mode. Simple - only if your USB cable has identified a free COM port for the Digirig. Usually this works well.  Last night it failed on two setups.

Probably because either a cable was “bad” (they are cheap) or the plug was not plugged all the way into the 4 pin socket (common error) or - more likely - the radio’s RF was getting back into the Digirig and causing problems on the USB port cable.

Often the transitter will LOCK on transmit when this happens.

So if the PTT is working (set in VARA FM to COM port and a number for the port) then the last step is to set the optimum TRANSMIT audio level.

Easy way - set the LEVEL to very low (-30dB is lowest) and press the VARA FM TUNE button. The radio should go into transmit mode - but low TX audio.

Listen to your own signal on an HT. You might hear a very faint single pitch 1500 Hz tune. Then graudally increase the audio level (to -20 dB, then -10 dB, all the way to 0 dB) until it sounds “about as loud as your own voice would have been had you plugged in a real mic to the radio”.  That is a first approximation for proper audio.

Goldilocks - not too soft, and not too loud.

VARA FM TUNE is as loud as your own voice - rough guide.

Now, for a rig with a 6 pin DATA jack (Nadine has a Yaesu) or the Icom 880? which also has a dedicated DATA jack - it is all much easier (usually).

The Digirig has a four wire AUDIO cable that carries the RX audio, the TX audio, a PTT wire, and a ground. That is four wires - and that is why the cable has FOUR (Tip, Ring1, Ring2, Sleeve) pins on that 3.5mm plug.  At the RADIO side of that cable, you likely have what is called a round “6 pin MINI DIN plug”. It is common to many radios and the pins do the same function on Yaesu, Knwd, Icom radios!!

Pin 1 is always transmit audio

Pin 2 is always gnd

Pin 3 is always the PTT (ground it to transmit)

Pins 4 and 5 always carry receive audio: pin 4=9600 baud (wide) and pin 5 = 1200 baud

The Digrig cable itself is wired to either pin 4 or pin 5 - it cannot be wired to BOTH!

Digirig has cables for each - sold separately of course.

My cable was labeled 9600 (so receive audio came from pin 4).

If you get receive audio from that cable (pin 4 or pin 5) then you do not need to plug in an external speaker - and you do not have to worry about where the VOL knob is set on the radio - and you don’t usually have to worry about the radio’s squelch knob.

That makes it EASY. Usually pin 4/5 audio bypasses the radio’s SQUELCH knob - but not always.

The dedicated FM radios that have that DATA socket are thus easier to set up for digital modes with any external sound card. Knwd had the popular Knwd V71A and D700/710. I had an Icom 2720 and 2820.

Yaesu has odd 10 pin ports for data, but Yaesu sells a 10 pin to 6 pin “adapter” and I think Nadine owns one. Cliff in Phila ARES has a Yaesu fT6000 and his is working fine with a DRA sound card - consult Cliff KC3PGT.

The Digirigs are small, cheap, well made and have a COM port (for PTT)

Also Dennis K0TX is very helpful.

His web page is full of suggestions.

BUT there is no instruction MANUAL - bummer.

The SignaLinks are more expensive (over $120) plus cables but these do have those RX level knobs and TX level knobs. However, the SignaLink has no COM port. It MUST use its own audio as a VOX (voice actuated relay) to achieve a PTT signal. It works, yes, but it is much trickier to set up with Winlink modes (ARQ) so I do not recommend SignaLinks to rookies or ARES radios. See a QST article April 2022 on a Baofeng and Sound card I wrote up as a test.

The best sound cards (my opinion) are made by MastersCommunications.

These are called  “DRA” (digital radio adapters) and there are many models for many radios. I have six of them right now.

Almost all of us in Chester ARES/RACES have one.

These achieve a PTT (send) by neither VOX nor COM port. 

But PTT works fast and VARA FM recognizes these as RA adapter for PTT.

You don’t need to know how they work…. way too messy to explain.

There are hamfests coming up soon (Warminster in May, Kimberton in August) and your DELCO folks can pick up a sound card if they need one.

I do not suggest you use the soundcard DEFAULT in a laptop.

Yes it can work, but you don’t want Windows sounds into the ham bands.

I also have a few older Rigblasters that can work with any radio with the correct cable.

One problem that gets messy:

SignaLinks have a 16 pin jumper block inside that MUST be set by wires or a plug that match the CABLE and RADIO.  But once set up, they work fine.

The Digirig has ONLY a 3.5mm (4 conductor) socket for both RADIO (audio) and SERIAL (CAT control).

Thus, you need the proper RADIO cable or CAT cable to fit your radio.

Watch out - there are cables that have the right plug, but the wiring is different for a 8 pin modular RJ45 plug for Icom vs. Yaesu.  The RJ45 mic plugs are NOT the same for different manufacturers!!!

I’ve played with most HF/VHF radios and a dozen sound cards. They all work. But rookies will struggle especially when forced to use a MIC jack for TX audio, and a SPEAKER jack for RX audio. PTT is its own problem.

For any DELCO ops who want to learn VARA HF SSB this is a different ball game.

There are a few local HF SSB gateways on 80/40/30/20 meters.

You may want CAT (rig control) and much different VARA HF modem.

Then Winlink controls the PTT function, not VARA.

We should hold more sessions where folks try to use their own radio for VARA FM on 2m.

We can also practice HF for those General class hams who have HF SSB radios.

80m is very popular for regional EMCOMM.

Saturday mornings are good for me.

VARA is gaining popularity with a new app called VAR AC (written by a ham in Israel) and it is FREE.

best wishes,
Barry k3eui