Is there a reason why people think it’s RF pickup on the coax line and not on the audio line?
Wouldn’t the audio line be a more direct and damaging route to the chip? ?
My thought is that feedback or not, the RF is going out the antenna and then the audio line is acting as an antenna and is picking up the RF and burning out the chip because we know the chip operates in bridge mode and therefore the leads are not grounded…
73, Tom Sent by phone, please forgive my brevity and poor typing.
toggle quoted message
Show quoted text
On Jan 8, 2024, at 6:29?PM, Scott N4AAJ <scottfusilier@...> wrote:
?@Larry N0SA,
I also only work CW and had headphones plugged into the accessories audio cable that comes with the rig - not the speaker mic as it's headphone output plug is mono (the accessoriescable.is stereo). I normally run 5 watts CW when operating.
When mine failed I was running a tone (set to 30 in the menu) into an Elecraft T1 on 28mhz tuning an end fed random wire. It was a normal tuning cycle and it did complete. I had the headphones in when th audio stopped part way through the tune cycle.
When I get the rig back I plan to run a choke on the coax going forward.
As I stated in another post, the rig see.s to be sensitive to RF on the coax at 15m, 12m, 10m, and 6m. I've had it actually shutdown on me while trying to tune at low power on these bands. None of the other bands seem to have the same affect on the 599.
Hope this helps and that you never experience this issue.
73 de N4AAJ
Scott Fusilier
|
Where is the best location to place the ferrite beads and the best place to buy them??? ? Ammed Ismail KN6STX ?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]> On Behalf Of Larry Naumann Sent: Monday, January 8, 2024 5:38 PM To: [email protected]Subject: Re: [Lab599] Audio Chip? ? Scott
?Thanks for the info. I seldom run on 15m and higher.
Nice to have a bit more info.
Maybe it is time to put on some ferrite beads.
Larry
n0sa
|
Scott
?Thanks for the info. I seldom run on 15m and higher.
Nice to have a bit more info.
Maybe it is time to put on some ferrite beads.
Larry
n0sa
|
@Larry N0SA,
I also only work CW and had headphones plugged into the accessories audio cable that comes with the rig - not the speaker mic as it's headphone output plug is mono (the accessoriescable.is stereo). I normally run 5 watts CW when operating.
When mine failed I was running a tone (set to 30 in the menu) into an Elecraft T1 on 28mhz tuning an end fed random wire. It was a normal tuning cycle and it did complete. I had the headphones in when th audio stopped part way through the tune cycle.
When I get the rig back I plan to run a choke on the coax going forward.
As I stated in another post, the rig see.s to be sensitive to RF on the coax at 15m, 12m, 10m, and 6m. I've had it actually shutdown on me while trying to tune at low power on these bands. None of the other bands seem to have the same affect on the 599.
Hope this helps and that you never experience this issue.
73 de N4AAJ
Scott Fusilier
|
Pete,
?So true but no other list for portable rigs has many notes of this type of audio failure, that’s how we know the failure rate of the audio chip is much higher with the lab599 than other more popular portable rigs. Not only that, but we can also say that because other portable rigs don’t commonly have this problem, and many of those users use end fed wires regularly, that there is some design issue here that can be corrected. ?That’s all I’m saying. ?
Do we know of any other portable rigs that have an audio chip in bridge mode as does the lab599, or is that unique in terms of portable rigs? 73 Tom, N2YTF
Sent by phone, please forgive my brevity and poor typing.
toggle quoted message
Show quoted text
On Jan 8, 2024, at 3:28?PM, Larry Naumann <n0sa@...> wrote:
?I would be curious as to the output power level at the time of failure.
I only use 2 watts in the TUNE position and run 10 watts cw output.
I only work CW and never connect the mic./speaker combo.
It seems most of the failures were with the mic./speaker connected.
I made a special short cable that I can plug my earbuds into.
I occasionally use EFHW antennas and a small vertical that sits within ?6 feet of the radio.
On my EFHW I use about 10 feet of coax.
I have never had a problem but I have 3 of the audio chips on order just in case.
Larry
n0sa
|
I would be curious as to the output power level at the time of failure.
I only use 2 watts in the TUNE position and run 10 watts cw output.
I only work CW and never connect the mic./speaker combo.
It seems most of the failures were with the mic./speaker connected.
I made a special short cable that I can plug my earbuds into.
I occasionally use EFHW antennas and a small vertical that sits within ?6 feet of the radio.
On my EFHW I use about 10 feet of coax.
I have never had a problem but I have 3 of the audio chips on order just in case.
Larry
n0sa
|
Re: FT4/FT8 TX sounds coming directly from radio
The OPs comment reminds me of when I worked on the flight deck of the USS Forrestal in 1971 we wore hearing protectors, actually David Clark headsets to protect our ears also if you were smart you used earplugs. I noticed a buzz in my ears every time the large search radar antenna at the top of the island would pass me. I kind of thought this was crazy but it was true, there was so much power generated from the radar it actually caused a buzz in my ears.
|
Re: New Firmware available: v1.20.03
Could have been a small error reported and quietly fixed. Same happened a few releases back with spelling errors in the menu.
|
New Firmware available: v1.20.03
There seems a ?but the changelog was not changed since the previous v1.20.02. But the file differs from the previous one.
73 Stephan
|
Thomas,.other rigs have quite common failures, for example: finals on then earlier 817 caused just by batteries being left in the rig.? IC7300 screen failure and loss off power, etc etc etc
I think the TX500 is suffering from the effects of the current fad of EFHW antennas, which exhibit high voltages at the rig end of things!
73 M3KXZ
We know it’s a high rate because we can compare to ?the groups on other radios.? I have many rigs and many portable rigs.? Have a look at the groups for the 817,705,905. ? I haven’t seen many reports of audio chip blowout there and those rigs have sold many more copies (at least 817/705 have) than the lab599. ?
So the audio chip failure rate here on the lab599 is much higher than other rigs. ? Not good on a rig that is supposed to be tough. ?
The question we need to ask is not exactly what the failure rate is, but what is it about the design that makes it much more likely to fail than other rigs and how we can correct it.?
I suspect it may have to do with the audio chip being a bridge setup.? In a bridge setup neither audio line can be grounded.? If the audio chip was not a bridge setup then one of the audio lines could be grounded and perhaps that would help the chip against being burned out by stray RF during antenna tuning or during times when the rig is operated close to the antenna as one does when operating portable. ?
It is interesting that every blowout I have read about has happened during tx, and not rx—so this is likely not a problem with how the chip amplifies sound but is more likely a problem with how the chip is grounded (or not effectively grounded as the case may be) in my opinion.? These folks all seem to report audio ok, then tx, then audio dead. ?
Sent by phone, please forgive my brevity and poor typing. ?On Sun, Jan 7, 2024 at 04:55 AM, Larry Naumann wrote:
pretty high failure rate
How much in % ?
|
Hi Everyone,
I always use a coax with a string of toroids either a 1 foot attachment or the 50 foot with the toroids already in the 50 foot piece. ?I've done this initially when I received reports that my audio had a crackle or as they say "RF in the shack" sound. ?This is caused by RF on the outside braid of the coax feeding back to the radio. ?This is especially prevalent in end fed antennas typically deployed in POTA situations. ?It's especially prevalent when running 100 watts such as an FT891. ?Evidentially the audio chip is delicate for this back EMF so while I was deploying the toroids to improve my audio I'm also protecting my radio because the audio chip in my radio its still OK. ?I've place links below to the ABR industries two coaxes options that I use. ?This back RF is especially present if you do FT8 because of the constant RF transmission.
Below is Ham Radio Outlet who sells ABR industries cables. ?The LMR 240 lightweight coax options are great for POTA activations. ?They sell LMR 400 options too on their websites. ?BTW the Ferrite bead should be mounted at the radio end NOT on the antenna end to be most effective at blocking the RF coming down the coax.
The 1 foot jumper with the ferrite beads with an end mounted male and female PL259's
The 50 foot coax with the ferrite beads
The 100 foot coax the the ferrite breads
Hope you guys find this information useful. ?I highly recommend using them to improve your audio and protect your radios. ?And every radio not just the TX-500!
As Always,
Best 73,
David
K9AT
|
We know it’s a high rate because we can compare to ?the groups on other radios. ?I have many rigs and many portable rigs. ?Have a look at the groups for the 817,705,905. ? I haven’t seen many reports of audio chip blowout there and those rigs have sold many more copies (at least 817/705 have) than the lab599. ?
So the audio chip failure rate here on the lab599 is much higher than other rigs. ? Not good on a rig that is supposed to be tough. ?
The question we need to ask is not exactly what the failure rate is, but what is it about the design that makes it much more likely to fail than other rigs and how we can correct it.?
I suspect it may have to do with the audio chip being a bridge setup. ?In a bridge setup neither audio line can be grounded. ?If the audio chip was not a bridge setup then one of the audio lines could be grounded and perhaps that would help the chip against being burned out by stray RF during antenna tuning or during times when the rig is operated close to the antenna as one does when operating portable. ?
It is interesting that every blowout I have read about has happened during tx, and not rx—so this is likely not a problem with how the chip amplifies sound but is more likely a problem with how the chip is grounded (or not effectively grounded as the case may be) in my opinion. ?These folks all seem to report audio ok, then tx, then audio dead. ?
Sent by phone, please forgive my brevity and poor typing.
toggle quoted message
Show quoted text
On Jan 8, 2024, at 7:58?AM, Андрей Денисюк <lilo.chita@...> wrote:
?On Sun, Jan 7, 2024 at 04:55 AM, Larry Naumann wrote:
pretty high failure rate
How much in % ?
|
On Sun, Jan 7, 2024 at 04:55 AM, Larry Naumann wrote:
pretty high failure rate
How much in % ?
|
Re: FT4/FT8 TX sounds coming directly from radio
If it is still happening without Power Applied - you probably should take a break from Ham Radio for a while, LOL
|
FT4/FT8 TX sounds coming directly from radio
Hey All,
Just recently, I started hearing the Tx sounds for FT4 & FT8 coming directly from my TX500. There is no MIC/SP hooked up and I put my ear up to the radio and could hear the TX sounds.
Any else have this issue? Should I contact support??
Thanks!
Anthony KF0GTR
|
Re: tx-500 lost audio output
On Sat, Jan 6, 2024 at 04:28 PM, JM99 wrote:
"...is there any way to prevent blowing out the audio chip that us users can do...?
That would be helpful to know. ? -- 73, Norm/KC1BMD
|
Re: tx-500 lost audio output
So……..is there any way to prevent blowing out the audio chip that us users can do that won’t void the warranty or anything? ?Is it only occurring when using a headphone adapter or even with the stock speaker-mic?
How difficult is it to replace the chip? ?Is it advisable to just install a socket in place for easier replacement of the chip if it keeps failing?
|
Re: tx-500 lost audio output
Virtually the same happened to my radio. However, the email was immediately answered. They requested I verify no audio on the pin. Once that was verified, I was given an address outside the country to ship to. Only a couple weeks later, the radio was returned, repaired, no cost.?
Meanwhile I bought a spare just in case.? 73,
Bill Watkins K0WHW kf7yxs@...
toggle quoted message
Show quoted text
On Jan 5, 2024, at 22:52, Ammed Ismail <amiwood@...> wrote:
? Scott,
Email Roman at Lab599 in Russia and he will reply to you. Roman will get the Lab599 USA service center to reach out to you. I do believe parts are going to be hard to get unless Lab599 USA center has the parts already.? Best of luck, 73! Ammed Ismail? KN6STX On Jan 5, 2024, at 7:03?PM, Scott N4AAJ <scottfusilier@...> wrote:
?Several weeks backs I was preparing to activate a local park and the audio output stopped working on my tx-500. I was sending a low power carrier (tone with power=30) into my Elecraft t1 tuner at 28mhz to obtain an impedance match and the radios audio output stopped working. I was using the headphone adapter and have verified (with the speaker mic mic) that the issue exists inside the radio.
The radio seems to.work as it should in all other respects, just no audio out.
From reading previous posts on this group it looks like the audio IC may have failed. From what I understand the chip is an NXP TDA7056AT and many have failed before.
I've reached out (email and called) to Lab599's US repair service and did not initially get a response. Several days later I sent another email and got an answer. The answer said they were traveling for the holidays and would get back to me. Nothing... So I sent two more emails. Nothing yet... I sent another email to Lab599's support email today asking what to do to initiate a repair. On the site they say contact the service folks before sending the radio. I cannot.get a response.
Is this typical customer service for Lab599?
Can anyone please suggest an alternate service that would be willing to troubleshoot the radio's audio output issue or just simply reach the chip?
I love the radio and would.like to put it back I to service.
Thank you,
Scott Fusilier
N4AAJ
|
I was wondering if Lab 599 has changed the audio chip, the TDA7056at?
There seems to be a pretty high failure rate and I am concerned because the chip is no longer produced.
There was a reference to them maybe having changed to another chip.
Is this correct?
I am curious because it seems that getting it fixed and or getting a new chip may be an issue.
Larry
n0sa
|
Re: tx-500 lost audio output
Scott,
I have been wondering the same thing. ??
I noticed that 5B4AIY mentioned in his eham review of the rig that the audio chip operates in bridge mode and is dangerous. ?
I reviewed the datasheet for the audio chip and saw he was right. ?
The audio leads on the chip are floating, neither one is grounded as far as I can tell.?
Consider that the audio leads are connected to a coil in the speaker, and I could see high RF voltages being induced on the audio line—high enough perhaps to burn out the audio chip. ??
It would seem all the failures are from transmitting, not sudden failures during rx. ?To me that means RF is feeding back into the audio chip and burning it out. ?
I think the solution will be either a low pass filter on the audio lines or some diode setup to limit voltages on the audio lines vs ground. ?
In addition, have a look at a teardown of the rig online. ?Notice how the case internally is anodized and there is no ground strap between the boards internally. ? I wonder if there is also insufficient grounding within the rig. ?I believe a proper fix includes one or two ground straps between the boards.?
As a separate note on poor grounding on these sets, I opened my bp500 after receiving it back from repair for the overvoltage defect, and I saw that someone had scrapped off the tiniest bit of anodizing from the red cover and put some foil under it and under a circuit board screw in an attempt at grounding. ?I replaced that w a proper ground strap as the foil was mostly cut. ?This just shows me grounding wasn’t properly addressed throughout..esp on a rig that will most likely operate very close to an improvised antenna in the field. ?
Can someone who has a schematic of the rig give us an idea of a simple RF filter/voltage protective circuit for the floating bridge audio leads??
73, Tom, N2YTF Sent by phone, please forgive my brevity and poor typing.
toggle quoted message
Show quoted text
On Jan 6, 2024, at 9:55?AM, Scott N4AAJ <scottfusilier@...> wrote:
?I am curious if this failure could be avoided by using a torroid to isolate the audio line before it goes into the rig?
In my experience with the radio so far I've noticed feedback noise in the audio out any time I tune up on 15m, 12m, 10m, or 6m.? I've had the radio shutdown completely due to rf 'feedback' on the coax. This is with sending a carrier at reduced power. Adding an isolation torroid (rf choke) seems to cure the issue. In the future I plan to alway run an rf choke on the coax. Don't want to risk this failure again. I was not running a choke between the tx-500 and atu when the audionoutput failed.
?Wondering an audio line choke is necessary or could prevent the issue?
It should also be noted that I have other portable rigs thatbI run with the same configuration and they don't seem to be bothered by any feedback on any of the amateur hf bands.
Thank you for any feedback,
Scott N4AAJ
|
Ammed Ismail
Larry Naumann
Dave
George MM0JNL
Stephan HB9EAJ
David Holmgren K9AT "Ruffers"
ve3ega
Norm - KC1BMD