Rig is Icom IC-706 MK II G, software WSJT-X, Digirig connected easily, receives great, when transmits it cuts off after one second. When connected to dummy load transmit seems to work fine. Antenna used is simple 40 M dipole that I have used for years with MFJ tuner, with no problems. Ultimately I want to use this in the mobile to do POTA. Mobile antenna is Hamstick, ball mounted on rear quarter panel of mini van.
since it works with the dummy load, weâre looking at the antenna âsystemâ.
most likely it is RFI knocking out the computer/usb/digirig âchainâ.
try turning down the power, on the radio itself, to as low as it will go and see if it makes a difference.
other things to look at:
relocate the pc/usb/digrig assembly as far away from the tuner as you can.
remove the tuner from the radiation chain and try tx on just 40m (if your 40m dipole is resonant @ the FT8 freq)
hamsticks on my truck bed have worked very well.
hamstick with the âcoilâ right next to the van panel may be really difficult to tune up.
(tune up by whip length, not a matching unit)
good luck
kb0wlf
Thank you so much for reply. My attempts at transmitting have been at 40 W, I will go down a bit and give that a try. Actually I am not using a tuner in the mobile, a Dodge Caravan, and the low end of 20 M band is my best. I did tune using the whip length. Today I ordered a LDG 1:1 Unun which might take care of the RF problem. Thanks again, will keep you updated.
73, Kenny, KA3DCO
qsl
if you can get a stable tx cycle at lowest power (on the radio, full audio out from the software) then you can work out from there.
the 1/4 wave hamstick style antennae do a good job with enough metal on the âgroundâ side.
caravan has that
kb0wlf
Good evening, many thanks for your interest and know-how. This afternoon I made another attempt running 10 watts and still same thing, transmit one second and shut off. I have ordered device from HRO to remove common mode currents from antenna coax, should be here tomorrow. I will advise as to how that goes. Thanks again!
73, Kenny â KA3DCO
yes, a common mode choke is a good thing.
iâm wondering if your antenna system is resonant where youâre transmitting (for wsjt-x modes)
a half wave dipole fed with average coax makes for a really low RFI possibility unless it has a high swr.
the 1 second tx shutoff really does sound like RFI.
while waiting on the CMC, could you try:
unplugging the AUDIO cable from the digirig.
short/jump then connection of that TRRS plug at sleeve and ring2
(that is the 2 connections farthest from the tip (tip,ring,ring,sleeve)
so that would give you âkeyupâ but no audio and so no âpowerâ on SSB but you could eliminate or affirm troubleshooting so far.
good luck
kb0wlf
Good evening - I received and connected LDG RU-1:1 today and this made no difference in the operation, transmit still cuts off at one second. Something I did notice - I lowered the âPowerâ slider on the right side of WSJT-X screen all the way to Zero. Radio goes into âtransmitâ and does not shut off. However, there is NO output. I can set Power out on radio at 40 and still NO output. I can move the slider up to one or two increments before it goes back to the âone secondâ shutoff, still NO output. We are preparing to go on a trip Monday and I am throwing in the towel for the time being. When we get back I will likely get back to trying to get this to work.
Am back from vacation and hoping to tackle this again. Here are results from session I did yesterday.
Setup is as follows: Antenna is 20 M Hamstick mounted on truck (mirror) mount secured to copper rod driven in ground approximately 6 inches, six 16 foot radials attached to ground, a 12 inch jumper connected to mount, then LDG RU 1:1, then 55 ft. RG8X coax directly to IC-706 MKIIG. SWR is a bit less than 1.5:1. Antenna is at least 50 feet from radio.
When transmitting at 40 watts it still shuts off at one second.
Here is where it gets funny. I change WSJTX POLL INTERVAL setting (on Radio settings) to 15 and it works. I have read what this is but canât see any connection to transmit. I made on valid contact this way, only set up for short time. Also when transmitting there is and ignition type noise in radio speaker. Engine was not running at this time.
Any thoughts?
well, , the polling is how often the software, wsjt-x in this case, queries the âremote controlâ connection to the radio.
the troubleshooting results, in my sub-novice opinion, are still pointing at RFI âkillingâ the C-IV connection from digirig to radio.
when the polling is frequent enough to poll DURING a TX cycle AND it finds the connection lost, wsjt-x will abort the TX cycle (regardless of PTT method selected).
basically wsjt-x thinks the radio is âofflineâ and shuts down the PTT.
so, just for me, if you feel like it.
select, in wsjt-x, radio â NONE for cat/remote control.
make sure youâre âon frequencyâ manually and try a tx/rx cycle.
good luck
kb0wlf
Good morning! I am a Happy Camper!! I tried your suggestion, changing my specific radio model on RADIO page WSJTX and entered NONE, and it works perfectly, with or without the RU 1:1 Unun. To think of the four weeks I have been struggling with this and one simple step solves the problem. I have done two brief operating sessions from my van using 20 M Hamstick on ball mount on side of vehicle. Made two good solid contacts each session, Cuba, Puerto Rico, and Mississippi. I canât thank you enough for the help you have provided. This also points out the value of The Forum system. I enjoy doing POTA and hoping using FT8 the activity level will be better than it has been on phone for the past few months.
Again, many thanks â 73 â Kenny, KA3DCO
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glad itâs TX/RX ok.
iâm sorry i couldnât âfixâ the C-IV issue.
a project for another time? 
i used to run the icom 706/7000 radios mobile, even psk31.
i didnât use any remote control in the mobile though.
kb0wlf