Topics

uBitX PTT cycling

Vic WA4THR
 

Just finished the wiring of a v4 uBitX and I am running KD8CEC v1.1 with a 2.8" Nextion screen. Everything seems to work (not happy with the low and slightly distorted audio, but will address that later), and with no microphone plugged it it seems to be working just as expected and as it did with a breadboard layout before I started wiring. However, with the microphone plugged in to the 4-pin jack I added I am getting continuous cycles into and out of transmit about 5 times per second. If I hold PTT or press the CW key down (4.7K resistor is installed) it goes into steady transmit, but once release it starts toggling transmit again.

The microphone being used is a surplus Motorola speaker/mic that I've used successfully on my BitX40. It does have some unknown internal circuitry and shows about 1.4K between the PTT line and the electret mic line...nothing that affected the BitX40, but in that rig it was operating a relay and here it seems to be pulling down the A3 PTT input on the Raduino. My suspicion is that the load drops the voltage across the internal pullup resistor on the Arduino low enough to signal transmit, then it immediately drops out and returns to receive. So, without surgery on the microphone on a circuit I don't have any information about, isn't there something I could do here? Could I supply 5v through a dropping resistor directly to the A3 input, and would I have to disable the internal pullup resistor if I did? Can I adjust the trip point of the A3 input through software somehow?

=Vic=

Guy Skeer
 

It is clear to me that I am so very less skilled than most here.

I have a brand new Board and Raduino, completely stock, just connected everything and powered up.  Lights up.  Encoder works.  No Audio.  When I Push PTT, T/R relay Chatters similar to post above, about 5 cycles.  Release PTT, and Receive LED lights.

I noted that a Red LED on the Raduino cycles in time with the T/R relay.

See the "Brand New" note above? Figured I killed My First Board and Raduino by connecting Power leads reversed polarity, caused by using a wrong color order connector provided by Case Manufacturer without checking.  But Both Radios have same symptoms (after correcting Power Wiring and Connector)!  No Audio at all, and Recieve mode quiet.  PTT Actuation causes same Chatter.

Hope this sounds familiar to somebody - I have built many, many kits over the Years. But this is my first foray into SMD and MicroComputer control...

Vic WA4THR
 

An update: Adding a pull-up 2.2K resistor between the 5v pin and the PTT line stopped the PTT cycling when the microphone was plugged in, so that is all working as expected, now. However, when modulated in SSB into an antenna with a modest SWR (2:1) I am getting RF into the Raduino causing it to go into "Band Change" mode and lock transmit on until I press the encoder button to acknowledge. This does NOT happen in CW, only when modulating in SSB and does not happen into a dummy load. So...some effort will be spent to see if I can relieve that symptom internally, although I do have an antenna tune available.

=Vic=

Vic WA4THR
 

Guy, what are you using for a power supply? If the voltage drops you might be getting that intermittent cycling you describe. If that is a v4 uBitX board, the audio output is very low as delivered. I thought mine was dead as I couldn't even hear any expected receiver hiss at full volume on a dummy load, but on an antenna I am hearing signals.

=Vic=

Evan Hand
 

That happened to me and I solved it through proper grounding and ferrit clamped over the coax going into the rig.  I used 2 of the clamp on type.  Need to get them that fit over the coax, or else an isolating balun.  The RF on the coax came from an OCF dipole.

73
Evan
AC9TU

_Dave_ K0MBT
 

Vic
Might suggest that you try to get your radio working with the stock mic first. Could well find that the power output would be satisfactory. Then start modifying it.

Also would suggest that you look to decrease the swr. Have had a decent about of heating of the finals with 2:1. Perhaps symptoms would decrease.
73

Guy
Look at the cable from the front left of the mother board. I have had aftermarket cables that came with a radio case that were not making good connection. Had to disassemble the 8 pin cables and tighten up the connectors. The metal used in the ends of the connectors was very soft and not springy at all.
Dave

Guy Skeer
 

Message to Vic and Balfour: Thanks so much for Your interest and Your replies!

Grinding away in my Rest period (couldn't sleep, thinking of the nearly $350.00 I have spent on this "For fun" project)..SheWhoMustBeObeyed is NOT amused!

I went back and quadruple checked every path to/from the Front Panel Nexus Circuit Board, (supplied by separate contractor than HFSignals)...found a mis-connection that may have fritzed some semi-conductors....

Corrected the problem, and connected the original Main Board with its Raduino.  Everything seems to work as expected, Raduino lights up and runs through Boot, works well going through all menus.  T/R LED ans relay(s?) Click with PTT actuation and release.  Current does jump up a bit with PTT press, but whistling into mic does not cause any chanfe on the tiny meter on my Precision Regulated DC power supply.  

I hear nothing, not even crackle or hiss, with full twists of the volume control.  Will connect radio to my 40-Meter Dipole with SWR right at 1.2:1 in its sweet spot, a little latr in the Day.

Thanks again, for the Support, hints, and help!

73
Big Ugly Guy

Guy Skeer
 

Did not mean to leave You out of My thanks, Evan!

I suppose I could include My "Ancient of Days" Dentron SuperTuner to isolate the Incoming RF (if any)?

Just hearing from You Folks is Bucking Me up.  I was beginning to think that after over 30 Years dealing with Container Cranes' regulators and electronics' Gollywobbles, that I was "loosing it"...

Fraternally,

Guy Skeer, KD6RGZ

Guy Skeer
 

Headphone reveals some reception, but only one QSO heard on 20 Meters this Noon.  Transmission lights the Red LED, but cannot cause feedback with a Shortwave a foot away.  Mic not functional?  Still no audio from Speaker.

Lots of whistles and tones heard while tuning over all bands.  Some CW heard. Shouting into the microphone does not seem to take the current above .5 Amp on 40 Meters, according to teeny (+/- 20%?) meter on the Regulated Power Supply, set at 13 Volts.

Vic WA4THR
 

Have you tried keying the rig in CW to see if you get a carrier out? That will determine if you have an audio or RF problem. Lots of folks struggle getting the little electret mic hooked up right.

After adding a pull-up resistor to the PTT line and checking into the antenna through an antenna tuner, I've decided all is well with my base construction. Power output is higher than I expected on all bands, so I think that was a worthwhile improvement in the v4 boards. I love the Nextion interface! I think I may still be a few cycles off frequency. I used the OEM 4.3 sketch to initally set it with a second receiver that had a pan adapter and it was very easy and quick! Much better than the old method still built into the CEC sketch, but I will use the Memory Manager to tweak it a little to see if I can get it dead on swapping sidebands while listening to WWV when it is sending an audio tone.

=Vic=

Vic WA4THR
 

Well, it took a while of careful adjustments to the master frequency, but it is pretty much dead on and sounds the same on USB or LSB, now. So, I'll call phase 1 complete: The basic rig is working with no mods to the main board. I still need to add a bezel to the front panel, I think, to cover the gap on the right where the ribbon cable exits, but next up I will start mods: making sure spurs/harmonics are controlled, improving the audio output, adding AGC, perhaps some mods for mobile ops as I did on the BitX40, and maybe even start fiddling with the software.

_Dave_ K0MBT
 

Nicely done. Is that going into your car?

That is one thing I dislike all black. Have some equipment that way, black knobs on a black cover.

Vic WA4THR
 

At first I was not going to put this one in the car, but I am liking it so much that I just might and enjoy a bit more power than I get with the BitX40. I do have it set up with a fused lighter plug for power, but on the -40 the alternator whine was very loud, so I installed an internal filter on the power line that completely eliminated that. I'll probably test this one and see if there is room to do the same if needed, just to have the flexibility.

=Vic=

Mike Short
 

Go to k0bg.com for help with mobile operations. You put a bandaid on the problem, and didn’t fix it.  HF mobile is nothing like V/UHF. Using a lighter plug is one of the worst things you can do. You can’t just toss a HF radio in a vehicle and expect it to work.

what antenna are you using and how/where is it installed?

mike

Mike Short
 

Plastic cases and RF do NOT Go together. Have you ever seen a radio in a plastic case?
The answer is no. Manufacturers would use plastic as it is cheaper, but the don’t because of shielding requirements. At a minimum line the complete inside with metal/foil and make sure the power, antenna ground, connectors and all boards are bonded together. You have RF running everywhere, and until you get it under control you are going to have problems. Doesn’t matter if it is in the vehicle or shack. Mobile exacerbates existing problems. 

Evan Hand
 

I had looked at using copper clad tape with conductive adhesive as a solution to shielding a plastic case.  There is also Y-Shield paint.  Have not used either yet, though leaning towards the tape.

Based on my experience on the bench with RF issues, I would have to agree with Mike to install the shielding.

My opinion, you are entitled to yours.
73
Evan
AC9TU 

Jack, W8TEE
 

Al's used the tape and, while effective, it's not the easiest thing to apply plus you need to solder the pieces together across breaks.

Jack, W8TEE

On Friday, February 1, 2019, 2:25:03 PM EST, Evan Hand <elhandjr@...> wrote:


I had looked at using copper clad tape with conductive adhesive as a solution to shielding a plastic case.  There is also Y-Shield paint.  Have not used either yet, though leaning towards the tape.

Based on my experience on the bench with RF issues, I would have to agree with Mike to install the shielding.

My opinion, you are entitled to yours.
73
Evan
AC9TU 

Evan Hand
 

Jack,
So the conductive adhesive doesn't work and you need to solder as well?  That would not be good.  Guess I will forgo the plastic case I bought for the second rig.

Thanks for the information
73
Evan
AC9TU

Jack, W8TEE
 

I've used many plastic cases and never had a major problem. I was talking about something like clam-shell cases where they break apart to get inside and there are no metal screws holding metal flanges together. In those cases, you might want to solder a wire between the two halves.

Jack, W8TEE

On Friday, February 1, 2019, 2:35:42 PM EST, Evan Hand <elhandjr@...> wrote:


Jack,
So the conductive adhesive doesn't work and you need to solder as well?  That would not be good.  Guess I will forgo the plastic case I bought for the second rig.

Thanks for the information
73
Evan
AC9TU

Albert Peter
 

Conductive copper tape works very well but the drawback are

  • Expensive
  • Really a pain to install.

 

I would look for a metal case like the one shown at our website:  www.hamradiodesigns.com.  They are all metal, except for the plastic connecting trim.  They are available on eBay in several sizes from multiple vendors.  The Aluminum front and rear panels are not very thick, but the metalis fairly stiff.  I really like the result.

Al

AC8GY

 

Sent from Mail for Windows 10

 

From: Jack Purdum via Groups.Io
Sent: Friday, February 1, 2019 2:27 PM
To: BITX20@groups.io
Subject: Re: [BITX20] uBitX PTT cycling

 

Al's used the tape and, while effective, it's not the easiest thing to apply plus you need to solder the pieces together across breaks.

 

Jack, W8TEE

 

On Friday, February 1, 2019, 2:25:03 PM EST, Evan Hand <elhandjr@...> wrote:

 

 

I had looked at using copper clad tape with conductive adhesive as a solution to shielding a plastic case.  There is also Y-Shield paint.  Have not used either yet, though leaning towards the tape.

Based on my experience on the bench with RF issues, I would have to agree with Mike to install the shielding.

My opinion, you are entitled to yours.
73
Evan
AC9TU