Search found 38 matches

by John
24 Jul 2022, 12:41
Forum: Troubleshooting
Topic: SWR Meter affected by Audio cabling?
Replies: 2
Views: 129

Re: SWR Meter affected by Audio cabling?

That sounds an awful lot like RF coming down the outside of your coax due to an unbalanced coax cable running to a balanced antenna. That can cause all sorts of glitches and wandering readings to occur.
by John
24 Jul 2022, 12:35
Forum: Troubleshooting
Topic: Transmits all modes except CW.
Replies: 12
Views: 448

Re: Transmits all modes except CW.

Hi. I see in your original post you state " but for some reason tonight it won't transmit on CW using the PTT button." Your comments regarding this very unusual problem seem to narrow down the possible source of the problem to the keying firmware, since essentially all of the hardware invo...
by John
13 Jul 2022, 18:51
Forum: General Information
Topic: Display noise
Replies: 8
Views: 422

Re: Display noise

Is there any reason not to simply add an on/off switch for the display to shut it off when not needed in order to stop noise? It would also save power. I'm mounting my rig in a somewhat larger metal box, so a switch for the display would be no big deal. I was already planning on it as an energy-savi...
by John
13 Jul 2022, 18:37
Forum: General Information
Topic: Add On Features 2023?
Replies: 2
Views: 305

Re: Add On Features 2023?

I wouldn't say ham radio is completely superior communication to cellphones. I would say it is very different, and far superior during times of emergency. Cellphones require every part of large, sophisticated networks to be functioning properly in order for them to work at all. When the cell-tower i...
by John
11 Jul 2022, 15:59
Forum: Troubleshooting
Topic: Main board failure
Replies: 5
Views: 335

Re: Main board failure

I use an infrared thermometer gun to check the temperatures of devices in my circuits. It's not as quick or convenient as an IR camera for finding shorts and heat problems, but it works well and provides a precise value for the temperature.
by John
08 Jul 2022, 16:50
Forum: Troubleshooting
Topic: SSB TX sounds way off frequency
Replies: 14
Views: 521

Re: SSB TX sounds way off frequency

I'm no expert, but if you've tuned around and it still sounds "tinny and robotic" and unlike other SSB signals, then I would suspect some modulation problem other than it being off frequency. Have you tried an external microphone?
by John
08 Jul 2022, 03:37
Forum: Troubleshooting
Topic: Experience with Amazon kit and troubleshooting
Replies: 7
Views: 418

Re: Experience with Amazon kit and troubleshooting

Fun little rigs, aren't they? And amazing performance for the size and money. Firmware definitely rules. Cores inductance and losses do vary, perhaps by as much as 5 or 10%, not only from different suppliers, but even between batches from the same supplier. {"40m is still low. Transmitting belo...
by John
06 Jul 2022, 07:54
Forum: Troubleshooting
Topic: 0W output power on all bands after removing a turn from L31
Replies: 4
Views: 300

Re: 0W output power on all bands after removing a turn from L31

It's possible that when you removed 1 turn from the coil you did something that changed the circuit the FET's were driving through and a high VSWR blew up the FET's. Perhaps there was still insulation on the wire of the toroid, or a small solder bridge occurred when you removed the wire from the tor...
by John
06 Jul 2022, 07:28
Forum: Troubleshooting
Topic: Problem connecting to external PA
Replies: 15
Views: 752

Re: Problem connecting to external PA

You have said it "will not operate" with the mod, but you didn't mention what was actually happening. Does the amp do nothing when you press TRANSMIT? Does it key the transmitter the moment you push in the plug? Have you observed the voltage on the (tr)uSDX transmitter keying signal going ...
by John
04 Jul 2022, 22:31
Forum: Troubleshooting
Topic: Problem connecting to external PA
Replies: 15
Views: 752

Re: Problem connecting to external PA

"Unfortunately, this does not happen – DESPITE having the correct wiring on the connector(s)." The question is, "What is the correct wiring on the connector?" All the cable for your amplifier's transmit function needs to do is short together. Polarity doesn't matter. It will work...
by John
25 Jun 2022, 20:19
Forum: General Information
Topic: Sticky: Post (tr)uSDX questions for the developers (Manuel DL2MAN and Guido PE1NNZ) in here
Replies: 132
Views: 20826

Re: Sticky: Post (tr)uSDX questions for the developers (Manuel DL2MAN and Guido PE1NNZ) in here

I saw a posting in the forum about an upgraded schematic for the radios having been created, and since when I was troubleshooting the rig after assembly I found I had some trouble reading the one that's presently available I would like to know if the licensing problems have been resolved so I can ge...
by John
29 May 2022, 10:43
Forum: Troubleshooting
Topic: Dropped a clanger
Replies: 2
Views: 313

Re: Dropped a clanger

Hi Martin. From context, I'm guessing that "dropped a clanger" means you did something that wasn't good. I took a quick look at the Gerber trace files, and if you pulled the pad off the bottom of the board it doesn't much matter just as long as you can top-solder the coil leads, since, (if...
by John
29 May 2022, 08:48
Forum: General Information
Topic: (tr)uSDX - Alternative Band Setups available
Replies: 79
Views: 11453

Re: (tr)uSDX - Alternative Band Setups available

AC9YY, to the best of my understanding, the bias level is not a power adjustment, and shouldn't be used as such. Yes, it does have an affect on the absolute power output, but that's a side-effect, and not typically a good thing since the bias voltage is an offset used to set the point where the FET'...
by John
20 May 2022, 06:15
Forum: Troubleshooting
Topic: PA Fets blown by connecting USB?
Replies: 13
Views: 801

Re: PA Fets blown by connecting USB?

I can easily see people hooking up their 12V and USB cables for CAT operation without first attaching an antenna or dummy load, and not realizing that the CAT software drivers may be pulsing the transmitter before the system is all set for 'transmit' modes, so that could be it. 'Random' power-up and...
by John
20 May 2022, 05:42
Forum: Troubleshooting
Topic: First power up and getting a large number in the display?
Replies: 6
Views: 355

Re: First power up and getting a large number in the display?

I'm not exactly sure how these things work, but I think you might want to delete your serial number from your post so it doesn't get spread around and misused.
by John
19 May 2022, 00:34
Forum: Troubleshooting
Topic: PA Fets blown by connecting USB?
Replies: 13
Views: 801

Re: PA Fets blown by connecting USB?

I have a couple of ideas, based simply on my R&D and repair experience, since I've not yet hooked up both a PC and a 12V supply to my (tr)uSDX, and have run into no problems as yet. But first, 2 caveats: 1.) I'm not an EE. I don't even have an Associates degree. 2.) I have a good deal of trouble...
by John
17 May 2022, 19:49
Forum: Troubleshooting
Topic: (tr)uSDX power, efficiency and filter optimisation
Replies: 161
Views: 19603

Re: (tr)uSDX power, efficiency and filter optimisation

A class E amplifier properly tuned using good components is inherently more efficient than a class AB amplifier. Obviously these rigs in kit form have not been optimally tuned, nor have the manufactured units, because optimal class E tuning on 5 bands takes time that can't possibly be put into a $10...
by John
11 May 2022, 03:10
Forum: Troubleshooting
Topic: band 6M and 4M
Replies: 1
Views: 269

Re: band 6M and 4M

If I understand it correctly, the (tr)uSDX has been designed to have a standard hardware and firmware format so it can be built inexpensively, and supported here by the original designers and there won't be an assortment of weird variant, undocumented Chinese knockoffs produced by unscrupulous vendo...
by John
01 May 2022, 20:52
Forum: Troubleshooting
Topic: (tr)uSDX power, efficiency and filter optimisation
Replies: 161
Views: 19603

Re: (tr)uSDX power, efficiency and filter optimisation

Tobias,
You might try playing around with the number and wire gauge of turns on L15. A few more turns on L15 on my RF bd improved my RF output efficiency over 5% on the 20 meter band when running on 12V or 13.8V. I haven't had time to play with the other bands yet.
by John
01 May 2022, 20:39
Forum: Troubleshooting
Topic: SSB BW Settings...
Replies: 9
Views: 800

Re: SSB BW Settings...

I thought that was odd, as well. But if I understand things correctly, (and I may not,) these digital audio bandpass filters are no longer just 'low-pass' filters of varying bandwidths like analog filters used to be, but are actually designed to be 'band-pass' filters that cover just the range of fr...
by John
30 Apr 2022, 22:50
Forum: General Information
Topic: My combination *Rxxxx*/Chinese Up Tech (tr)uSDX
Replies: 5
Views: 641

Re: My combination *Rxxxx*/Chinese Up Tech (tr)uSDX

I'm curious what the efficiency numbers were for each band before you tuned them.
by John
29 Apr 2022, 23:14
Forum: General Information
Topic: Reducing output power
Replies: 8
Views: 799

Re: Reducing output power

A more long-winded reply. Some hams believe bias voltage for either bipolar or FET transistors sets the power output. They are wrong. To the degree it does affect average power output it is a side effect, and typically a bad one. The bias voltage/current is meant to get the base/gate transistor volt...
by John
24 Apr 2022, 12:00
Forum: Troubleshooting
Topic: Power output
Replies: 1
Views: 280

Re: Power output

That is one of those common sense things that is utterly obvious once we think about it, but we don't tend to think about it, so we sit there randomly changing things until something works. Thank you for posting it so I will remember to think about it and work smarter as I tune the toroids.
by John
22 Apr 2022, 00:05
Forum: General Information
Topic: Sheet Metal Enclosure - 1st Draft
Replies: 23
Views: 3356

Re: Sheet Metal Enclosure - 1st Draft

My first thought is that a metal case would be good for RF isolation. My second thought is a concern that a metal case will detune the tuned toroid LC circuits that are nearly (or actually,) touching it. As much as we read that the magnetic fields of toroids are held entirely within the toroid, they...
by John
21 Apr 2022, 23:48
Forum: General Information
Topic: TOROID T1 T2
Replies: 14
Views: 1021

Re: TOROID T1 T2

The 2 gray transformer toroids need to be wound in the direction such that the 7 turn leads will essentially drop straight down to the proper holes. That was the only part of Manuel's video I found unclear. As I recall, that part was done with his hand just slightly blocking the coils and the toroid...