SSB TX sounds way off frequency

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2E0PJY
 

Posts: 10
Joined: 01 Jul 2022, 16:19

SSB TX sounds way off frequency

Post by 2E0PJY »

Hi Everyone

My first post here, want to start off by saying this forum has been invaluable in helping me get my kit built which I completed today. I have spent this afternoon tweaking the efficiency and output power and have got some very satisfying results with all bands between 79 & 82%, power around 4.8 - 5.9 watts so I am happy with that. I went ahead with some on air testing and found that the frequency was off by looking at the bandscope on my FT-891, I managed to get it spot on by changing the reference frequency to 26998950. I have tried SSB and its not working as I would expect, so I would be very grateful for any advice on what to do next, this is the issue. With the truSDX tuned to 14.250 and my FT-891 at the same frequency I tried a test transmission using the internal mic (truSDX is on a dummy load my FT891 is connected to my main antenna). The received audio in unintelligible it sounds like its way off frequency (tinny and robotic if that makes sense!). I tried tuning around on the Yaesu and could not find a spot where it sounded ok. I dont want to just mess about with things randomly so thought I would ask the forum experts for some much needed advice!

Thanks and 73
Paul 2E0PJY
John
 

Posts: 49
Joined: 19 Feb 2022, 08:56

Re: SSB TX sounds way off frequency

Post by John »

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?
2E0PJY
 

Posts: 10
Joined: 01 Jul 2022, 16:19

Re: SSB TX sounds way off frequency

Post by 2E0PJY »

Not yet waiting for a baofeng one to arrive from eBay so I can wire it in. It sounds very strange and certainly what I have experienced with other radios when they are out of alignment. Everything else seems to be working FB so I would really like to get this resolved.
N4XTL
 

Posts: 24
Joined: 08 Jul 2022, 01:44

Re: SSB TX sounds way off frequency

Post by N4XTL »

It's interesting that you had to decrease the frequency reference setting. Most radios I have seen online, and my own, needed to be increased by about 1 to 1.1 kHz. Just for experimentation, ignore the FT-891 band scope and set a reference frequency of 27001050. See if that improves your SSB audio.
2E0PJY
 

Posts: 10
Joined: 01 Jul 2022, 16:19

Re: SSB TX sounds way off frequency

Post by 2E0PJY »

Was certainly under frequency according to the band scope on the 891. I will for sure try what you said though.
wa2t
 

Posts: 180
Joined: 01 Jan 2022, 16:30

Re: SSB TX sounds way off frequency

Post by wa2t »

N4XTL wrote: 08 Jul 2022, 17:02 It's interesting that you had to decrease the frequency reference setting. Most radios I have seen online, and my own, needed to be increased by about 1 to 1.1 kHz. Just for experimentation, ignore the FT-891 band scope and set a reference frequency of 27001050. See if that improves your SSB audio.
FWIW, all 5) of the units I built needed the frequency decreased.

73,

Robert, WA2T
N6ALT
 

Posts: 21
Joined: 02 Jan 2022, 20:02

Re: SSB TX sounds way off frequency

Post by N6ALT »

Same here, both of mine needed the ref frequency decreased.

Joel
N6ALT
Murphyv310
 

Posts: 52
Joined: 18 Apr 2022, 19:33

Re: SSB TX sounds way off frequency

Post by Murphyv310 »

Hi.
It's really difficult to test these radios with another receiver close by even with a dummy load. Reduce the power output by running on the USB connector only this may improve matters.
Regards, Trevor. MM0KJJ
DL2MAN
 

Posts: 706
Joined: 30 Dec 2021, 19:18
Contact:

Re: SSB TX sounds way off frequency

Post by DL2MAN »

You can calibrate RefFreq also by using HF Time Signals:
https://www.dxinfocentre.com/time.htm

73 Manuel; DL2MAN
2E0PJY
 

Posts: 10
Joined: 01 Jul 2022, 16:19

Re: SSB TX sounds way off frequency

Post by 2E0PJY »

Thanks everyone for your helpful advice so far.

Over the weekend I spent a few hours on my radio and I followed the directions to tweak the filtering which required me to do a bit of tweaking on the toroids and its pretty much spot on now. I used an audio spectrum analyzer to set the reference frequency and managed to get it at 502Hz by changing the frequency. SSB still isn't working for me though, I asked a friend who is about 30 miles away to listen to my signal on 14.100 USB he is an SWL but has a good receiver. The test confirmed that my audio is entirely unintelligible. Next step was to wire up a baofend hand mic to the radio and test with that, same result unfortunately.

So I am at a bit of a loss here, and may resort to buying a pre-built unit and reserve this one for spares unless anyone can offer any further advice?

73, thanks all.
G3CWI
 

Posts: 12
Joined: 11 Jun 2022, 16:47

Re: SSB TX sounds way off frequency

Post by G3CWI »

Not a great idea to carry out tests on 14.100 as it is reserved for the international beacon project - a long running propagation aid. https://www.ncdxf.org/beacon/index.html
2E0PJY
 

Posts: 10
Joined: 01 Jul 2022, 16:19

Re: SSB TX sounds way off frequency

Post by 2E0PJY »

True but for the most recent test both rigs were connected to dummy loads.
2E0PJY
 

Posts: 10
Joined: 01 Jul 2022, 16:19

Re: SSB TX sounds way off frequency

Post by 2E0PJY »

Actually just to correct your absolutely right I did run the test with my SWL friend using my main antenna so thanks for the advice I’ll use a different freq next time.

All other testing is done on dummy loads.

73
DL2MAN
 

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Re: SSB TX sounds way off frequency

Post by DL2MAN »

Can you provide a video, how you talk into the rig and how it´s beeing received ?
My best guess would be: Mic defective (try unsoldering it and use external one), or you´ve changed the settings of TX Gain. Should be at 4. Not higher.
Your Ref Freq is calibrated ?
Another thing I observed: I had a cheap chinese Substitute Power Supply for my Shack Computer.
Once I unplugged that, (tr)uSDX created clear signals.... It picked it up over the air, belive it or not.
Now I have original Power Supply and RF Noise is gone. (tr)uSDX is pretty sensitive for RF Noise nearby.
Could be anything from LED Light to Power Supply

https://www.youtube.com/watch?v=gW5r5JQRbus

73 Manuel; DL2MAN
2E0PJY
 

Posts: 10
Joined: 01 Jul 2022, 16:19

Re: SSB TX sounds way off frequency

Post by 2E0PJY »

So a quick update.

I believe the PCB mounted mic element is faulty. I was noticing very weak modulation which at best was extremely distorted so I de soldered it and there is no continuity between either leg to the casing of the unit. I dont think it was my soldering as I have done these before and was super careful not to "cook" the element looks like its a DOA component. I have now modified a baofeng spkr/mic as per instructions on this forum. It works however there is some bad feedback that is causing it not to work properly. If I key the mic in SSB I see a carrier on my s-meter even if there is no voice or audio. If I touch one of the plugs on the trusdx such as the PA socket the feedback goes away so it looks like I am getting RF into the audio chain somehow. I tried the radio on both a battery (usb) and my shack PSU with the same results. Also installed a couple of snap on ferrites to the mic lead to no effect. I feel I am making some small progress but still not there yet! Works great on CW though :D
AI7JN
 

Posts: 10
Joined: 26 Jul 2022, 21:03

Re: SSB TX sounds way off frequency

Post by AI7JN »

My SSB audio on the built-in mike is also very bad. I have ordered a new mike that is supposed to be wired for a uSDX, bu tt will take a month at least to arrive from China. I have a mono mike with only ground and audio. If I wire it to a stereo plug, leave the PTT tip floating, and tie the audio to both rings, will that work if I use the PTT button to transmit? What is the electrical activation for PTT? Is there anyone in he US or nearby who can get me a properly wired mike in a week?
AI7JN
 

Posts: 10
Joined: 26 Jul 2022, 21:03

Re: SSB TX sounds way off frequency

Post by AI7JN »

Found the schematic and wired the mike so it worked. As I thought, leaving the tip open allowed me to use the PTT button to key the mike. Ground and ring on the uSDX mike input are wired to the ground and tip of the mono mike. Polarity does not matter. Still wish there were a US source for properly wired uSDX microphones. The cheap mike I have still doesn't sound great.
db9pz
 

Posts: 15
Joined: 18 Apr 2022, 20:44

Re: SSB TX sounds way off frequency

Post by db9pz »

A lot of 'after-market' Baofeng-microfons have that problem! They are much 'to sensitive' to RF nearby! You always have problems with the most of them, ... !

A small capacitor, - it should be a SMD, - directly mounted on the capsules solder-pads in parallel, should help a lot!
(0.1nF or something similar, is O.K. to shorten the 'disturbing' RF !)

Also, take care, what Manuel advices in the 'owner's manual' of the "(tr)_u_sdx" .

Always use the recommend settings! When you 'experimenting' with them, do it 'slow' and carefull, don't 'over-shoot'!
Less is often more.

Hope you will find a solution, that's working for you!

73/72 de Markus ; db9pz
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