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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
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On Sun, Jan 7, 2024 at 04:55 AM, Larry Naumann wrote:
pretty high failure rate
How much in % ?
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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¡ªso 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.
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On Jan 8, 2024, at 7:58?AM, §¡§ß§Õ§â§Ö§Û §¥§Ö§ß§Ú§ã§ð§Ü <lilo.chita@...> wrote:
?On Sun, Jan 7, 2024 at 04:55 AM, Larry Naumann wrote:
pretty high failure rate
How much in % ?
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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
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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¡ªso 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 Jan 8, 2024, at 7:58?AM, §¡§ß§Õ§â§Ö§Û §¥§Ö§ß§Ú§ã§ð§Ü <lilo.chita@...> wrote:
?On Sun, Jan 7, 2024 at 04:55 AM, Larry Naumann wrote:
pretty high failure rate
How much in % ?
|
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
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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.
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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
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@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
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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
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Where is the best location to place the ferrite beads and the best place to buy them??? ? Ammed Ismail KN6STX ?
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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
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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.
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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
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Tom
?I agree with your line of thinking. It seems to me it is a good possibility that the headphone or mic. cable is picking up RF and taking it directly to the audio amp.
Larry
n0sa
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Scott, a while back I was testing out an end fed also using the Elecraft T1 and connected to the rig via a couple of metres of coax.?
As the T1 was going through the tuning cycle on 17m at about 3W I got a small RF bite off the corner of the rig. I immediately stopped tuning. If I hadn't been holding the rig I wouldn't have noticed this, and quite possibly by me taking the RF it prevented any failure.?
The length of wire I was using was 1.5 wavelengths long on 17m, and so certainly high voltage at the feedpoint. I wouldn't use an end feed at all now without either using a sufficient counterpoise (which effectively makes the antenna an off centre fed dipole) or having the rig grounded. The fact they put high voltage at the feed point is always going to present a risk to any rig and attached equipment (for example laptop for someone doing digi modes). A sufficient counterpoise is so easy to employ.
73 M3KXZ
@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 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
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I don't think 5 or 10W out of an antenna and picked up on the audio line would be anywhere near sufficient to cause any damage to the chip. I was parked up right next to someone running 200W on 11m earlier in the week and suffered no ill effects.
My gut feeling is that it's high voltage at the feed point of an end fed antenna with no adequate counterpoise or ground, as discussed in my previous reply to Scott.
73 M3KXZ
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. ?@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 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
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Hi Pete,
The high voltage is after the transformer, not before. At the antenna connector we have around 50 Ohms.
I think it's a combination of current mode and picking the HF up somewhere at the microphone input, I guess. But only Lab599 can answer that and find a solution to remedy this issue.
I use a small CMC at the antenna port, since without, I sometimes got a scratchy voice on 17m and above, due to common mode. I also never used a headset or similar. After about 400 SOTA activations using this rig with different EFHWs, fortunately my audio chip is still alive.
73 Stephan
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That may very be the case, Thomas. It makes more sense.?
Thank you for pointing it out. Scott N4AAJ
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. ?@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 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
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I can confirm that newer TX-500 radios have a different audio amplifier.? This radio has a date sticker that says July 2023.   73, - Trevor, N6TJL
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Same IC but different manufacturer.
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It also looks to be obsolete
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Larry Naumann
David Holmgren K9AT "Ruffers"
Ammed Ismail
Stephan HB9EAJ
Trevor Larson - N6TJL - 3163412