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Author Topic: TS-590s Low TX Power  (Read 9846 times)

Posts: 56

« Reply #15 on: February 03, 2014, 06:35:41 AM »

........ad0gi,  sri, I do not know anything more than what I read posted by the moderator of one of the '590 users groups.  time will tell.


Posts: 203

« Reply #16 on: February 03, 2014, 03:50:32 PM »


I have my Kenwood abt 2 yrs now or 2 1/2, just forgot how long

I know it is software version 05.
I didn't feel the urge of going though the troubles of updating it.
I am way to bad with computers to get it done right.

As far as I know, no fix is being published by Kenwood yet, why would they as long there are still lots of hams buying them, and as long there are hams saying there is no problem at all , you are just stupid and using wrong methode of measuring, why should Kenwood improve or fix their product.

73 Jos

Posts: 906

« Reply #17 on: February 15, 2014, 02:37:52 AM »

Well its a common problem in many radio brands.  Only the designers know what causes the problem.  Yes, I do use the term "power overshoot" interchangeably with power spike. Its the same thing in my mind. If you set the power to 10 watts and it goes over 10 watts its  a power spike that is being corrected because it overshoots its reference mark of 10 watts most of the time. On most radios its noticeable at keyup. When you look at the radios using a accurate oscilloscope you will  find that power over shoot is both minor and major. Thats why when you use a  sensitive grid tetrode amplifier you can notice  this problem very easily. You can also detect it on stations  because stations using grid tetrodes with radios that have poor power control loops splatter very badly.

ALC shoot is  a very common. The root cause of most splatter and power overshoot  problems is the poor design choice of using ALC on a SSB transmitter design. There is no need for ALC on SSB transmitter if it is designed correctly. This is before we start talking about  the use of ALC as a compressor like most ham transmitters. You can mold all these issues into one problem, and that one problem is poor transmitter design techniques and practices from all the ham manufacturers. Its just the same recycle junk designs from the tube era with updated solid state electronics.

 If you compare a commercial SSB transmitter like those used by the marine or professional HF users you find none of these issues. You will also find how clean they sound both from a audio perspective and also a splatter perspective. Ham radios seem to need being over driven to achieve clear audio and rated PEP. On commercial transmitters without speech processing there is no need to drive things to the limit to sound clear or  deliver rated PEP.
Again crap ham transmitter designs thats outdated. If you every get to test a Micom, Codan, or  Harris HF transmitter  try it and you will be surprised how clean and good they sound. Also look at the pep meter and note that these transmitters dont use speech processing. Now swap over to any ham transmitter without speech processing and you think the transmitter is faulty. This is how bad the drive chains typically are in the average ham transceiver.

It is great that TS590S hams are speaking out about this issue. However look how this issue has been going with brands such as Icom?    Yet despite these problems we still find the ARRL and hams giving these radios 5 star reviews.

"ZENKI - You use the phrase "power overshoot".  Is this interchangeable with "power spike" and "ALC overshoot"?  I ask because I was under the impression that there was a distinction between the later two and that I had just not come to a full understanding yet as to what ALC overshoot is."

Thanks all for the great replies!

Jos - Your post raises similar thoughts as those here:

In summary, the author states that his TS-590s power spike was the result of a 5ms delay between power being applied and the ALC activating.  By lowering the ALC reference voltage, he got rid of the power spike.  This also lowered his average SSB to 20W which he did not mind.

One of the things I don't understand is why the YouTube vids showing 100W PEP for the TS-590s, and there are many of them, do not show the power spike mentioned in this article, your post, and many other places including reviews of the TS-590s here on eHam.  It is even specifically mentioned on the firmware update page of the Kenwood site here:

"TX rise time power spike activates some linear amplifiers' input power protections.
(The firmware Ver.1.02 revises the ALC response characteristics to reduce the power spike.)"

But I have seen it mentioned elsewhere that in fact this firmware update did not solve the problem.  How long have you had your TS-590s and have you been updating your firmware?

I also do not understand why lowering the ALC reference voltage would get rid of the power spike if the power spike is the result of not having the ALC activating to begin with.  But as to this part, I guess if it works it works.

ZENKI - You use the phrase "power overshoot".  Is this interchangeable with "power spike" and "ALC overshoot"?  I ask because I was under the impression that there was a distinction between the later two and that I had just not come to a full understanding yet as to what ALC overshoot is.

K3LRH - I too have read elsewhere that Kenwood has a fix for all this but that it is a hardware solution not being put into production.  Instead, it is part of warranty service that one has to send the rig in for.

Posts: 906

« Reply #18 on: February 15, 2014, 02:56:20 AM »

Well we will watch this issue with interest. I have a Codan 9360 ex UN radio in my car and with no speech processing I get excellent reviews. If I plugged this radio into
most ham stations they would complain  that it does not drive their amps the same way. The fact is that this Codan radio has a perfect splatter free transmitter that delivers rated power output. The majority of the radios that you  have used use ALC as a form of compression. That is the wrong thing to do technically so your reference point for drive a radio is starting from a bad reference. You need to try a good commercial radio like the Codan and then compare the TS590S to that radio.

We find users of the K3 complaining about the same thing. The K3 does not drive their amps to the same levels blah blah blah and that the K3's compressor is not as effective as a Speech processor on brand X. They correct but only from a point of view of the radios that they used in the past were being drive incorrectly to cause a lot of splatter.If you ALC as a compressor and then  use a compressor and then tie this into your power control loop you end up with a overdriven mess that hams call a well driven clean signal. However when you compare this to a commercial SSB radio its sounds like crap. The K3 drives  correctly and its ALC functions correctly and its one of the reasons why the K3 sounds so clean on the air. I can only imagine how good the K3 would be with proper  50 volt  FETS in its PA. It would be the cleanest radio on the ham radio planet.

Anyway we will monitor the issue with the TS590S. I can notice the power spike because I use homebrew tetrode amplifiers which is sensitive on the grid current. When I use the TS590S by itself there is no issue. There are also a lot of hams who have cranked the TS590S up to 150 watts of output. This stupidity plays makes matters even worst. We have a radio that has a poor power output control loop and we get idiots turning the power up on the TS590s in the hope that they will improve things.

Kenwood have had PA issues  with most of their solid state radios. If you look at the PA designs and circuit details of all the kenwood its the same PA design in all models. All that changes is the final transistors or FETS. After the TS940S and TS950SDX all of Kenwoods smaller radios had crap splattering PA designs. The TS850S and TS870S both had transmitters that caused a lot of splatter at rated power output.

We can go on  about all Kenwood and other ham companies. The fact is that they all designing poor transmitters. Then we have companies like Flexradio  that produce even worst transmitters for hams. It seems the only transmitters that follow good design principles are the HPSDR radios and the K3. Both these radios need better high voltage FET PA's for improved IMD.

Hi Zenki

I have to disagree in your opinion.
Yes you are right the TS590 delivers 100 watts PEP.
Power spike issues however in the design of this radio , makes it not possible to drive it to decent compressed SSB powerlevels like other radios can, like a TS130, TS180, TS570, Hartkit 2000 (has HF clipping standard installed in the rig) ,  a FT847, FT817(D) FT857(D), 897(D)  FT450, FT1000MP, FT920 or others.
I tried to use the high frequency clipper on the TS590 but the ALC wouldn't let me drive the rig to its potential power levels like other rigs do. 

And no these radios were not overdriven and were modulated with outboard HF clippers and reached high levels of TX power in SSB and high compression levels without overdoing ALC and becoming as wide as a barndoor

I could even flip the whole PEP issue totally upside down by saying that the TS590 power can not be measured with a PEP instrument because the power spikes will tell you that it delivers 100 W PEP , and you are measuring PEP power of the spikes instead the PEP power of the actually transmitted audio.
I could be totally wrong in this way of thinking, but it could be spot on also.

I do not want to offend no one just I think it is fair to say that the TS590 has a serious SSB TX problem with power spikes.
To overcome this problem Kenwood set ALC levels such way that average power output is low in SSB.
If you do not mind the 3 dB loss fine but I think everyone should know this, before they buy this radio.

In CW it also has a power spike issue but I could solve that by turning down carrier level so low that at full CW 100 watt output it costs me 5 watts.

And no, trying to get SSB power higher by changing factory setting of menu 23 and 24 will not solve the low power problem , it will just increase the power spike problem very much.
And if you are using an amplifier , it will not be happy with these spikes getting up to 130-140 Watts.
And the spikes are very big even if you turn back the power of the radio to 25 watts there are still big spikes of say 60W that could trip a tetrode amp with protection very fast, or without protection it could damage the amplifier tubes and components.

So certainly do not try to resolve low power SSB by increasing factory menu 23 and 24 this will only give you more problems instead of less problems with the power spikes.

Lets not forget that the TS590 has excellent ears in SSB and in CW.
A big transmitter with bad ears is even worse as the 3 dB power loss in SSB.
And though you can not drive this TS590 very hard it does have very good SSB audio in TX.

Sorry to have to disagree Zenki, I certainly do not want to offend no one.
It is just time Kenwood got their act together and solve the power spike issue in the TS590 instead of trying to cover it up with a band aid.

But as far of getting their acts together Icom, Flex radio, Kenwood and Yaesu have enough to do because all these IF based DSP or SDR based radios have plenty of problems to solve with the quality of their 12V RF amps in getting the transmitted SSB signal cleaner, so the very good SSB RX in radios like K3, TS590, TS990, IC7700, IC7800, FTDX3000, FTDX5000, TENTEC Orion2, several SDR based radios, can be used to their full potential and will not be suffering from very poor quality transmitted SSB signals as wide as a barndoor.

It could have something to do with use of quality design and components and good engineering instead of building as much bells and whistles in to their radios to sell them as many as possible as expensive as possible.
And of-course these commercial companies are reaching their goal, their products do not have to be good, their goal is to make money on them as much as they can.
The money loaded hams are there to make sure they will keep selling them.

And of-course lots of hams should try to reduce the drive levels of their SSB TX so the transmitted signal of these radios stay clean and within reasonable bandwith.
Listening to the east European contest stations with huge amplifiers up to 10KW in weekends, I know what overdriving all ALC levels does with a transmitted SSB signal in effect to bandwith.
Living in the first hop area of Italy, LZ, UA, EA, YO, LY etc. I do know the results of a totally overdriven SSB signal with an up to 10KW power amp. into a 6 element monoband yagi or even stacked Yagis. The result is that these transmitted SSB signals that are up to 15 or even 20 KC wide.   

They could inform at PA0CHN in how he got his radio the Hartkit 2000 build so good that it still outperforms  these radios in both TX and RX quality.

It took Kenwood and Yaesu and Icom the lesson of the Elekraft K3 to find out that they can be beaten.
73 Jos 

Posts: 203

« Reply #19 on: February 19, 2014, 08:54:43 AM »

Hi Zenki and AD0GI.

I read this article at :
Yes I think the German is good and spot on.

Do not forget what he says.
If you do not look out with menu 23 AGC reference voltage, settings power spikes will be awfully great.
I have to agree with the German that power spikes in SSB are not only at beginning of transmission but at almost every word after a short rest or between 2 words.
The best way to reduce them is indeed lowering value of menu 23, though it will decrease average power even more the spikes will get even lower, but will not dissapear totaly.

Tnx Zenki for you very clear answer.

We will just wait and see what Kenwood will do in the near future.

73 Jos

Posts: 42

« Reply #20 on: February 22, 2014, 08:12:17 PM »

I am the owner of a TS-590 for about 2 years. The posts by PA1ZP and AD0GI are 100% correct. Also the comments about ALC and ham transmitters by ZENKI are correct.
 The ALC circuit in the 590 , the attack time is too slow and the release time is too slow. This is fixed value in hardware and cannot be changed in the service menu. I can see the hams on my simple scope on the PRO-3 that have played in the service menu to increase average ssb power. YOU ARE WIDE, lots of junk beyond 3 kc. This is on top of the already dirty tx's caused by IMD with the 12 volt amps.( had to get that in there, ZENKI--HI)
 I sent my 590 back to Kenwood service, they "realigned " the radio. What they did was adjust the ALC threshold to a lower value and while helping the power overshot issue, it also reduced the average ssb power. Now my radio( which cost about 1400.00) is 2db down from a K-3, ft-5000--etc. I have a 1400.00 radio with a very good receiver and 2db down in tx average power( Who could see 2db of difference?)
 Now there is a rumor in a yahoo group that Kenwood is going to release a " parts kit" to redo the ALC circuit. About 15 parts( ris and caps) that will correct this issue once and for all. We will see if this is rumor or if Kenwood releases this sometime in March(2014)
I am a CW operator and use the 590 on CW. Reducing the carrier control to where there is no ALC and power is just starting to drop- completely eliminates the power overshoot in CW.
The 590 is a great CW radio and on ssb, if audio is setup correctly is VERY close to ssb average power of other radio's.
Thank you all for your input,
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