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Author Topic: Split Conversion design of the new Kenwood TS-590SG?  (Read 22485 times)
K9MHZ
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« Reply #15 on: December 24, 2014, 06:15:17 PM »

Just plunking around the web, and with no more credibility than just that.....it looks like the SG is sporting some very impressive transmit purity waveforms, and some nice receiver numbers given its price point.  I've got no axe to grind in any manufacturer's direction, but someone in the sub-$2K pricepoint market would do very, very well with a new SG.

 
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KT0DD
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« Reply #16 on: January 01, 2015, 07:10:56 AM »

Well, the Sherwood numbers are out for the 590SG and they're pretty impressive for it's class.

Dynamic Range: 104db @ 20K spacing and 92db @ 2K spacing.

This, along with a relatively clean transmitter for under $2K makes this quite a bang for buck rig.

Looks like the I & Y boys have some catching up to do.

I'm just waiting for a $2K rig to come out with a built in panadapter / scope feature that you can directly plug in an external monitor into the radio without having to perform any RTL/SDR type hacks. I'm not going to spend $5-10K just to get a radio with this feature.
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K9MHZ
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« Reply #17 on: January 08, 2015, 05:08:53 AM »

Yeah, I'm just as guilty as the next guy in assuming (funny how that word is spelled) that big, expensive, and Icom automatically meant good stuff.  Of course, the SG wasn't out when the 7700 was released, but now that it is, the evidence is loud and clear that big dollars don't mean big numbers in performance.  At age 55 and almost 40 years in the hobby, I'm going to be open-minded about all gear (finally). Being a healthy sceptic is a good place....just hate that it took so long!

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ZENKI
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« Reply #18 on: January 09, 2015, 01:16:09 AM »

Who established that the TS590SG  had a clean transmitter? I doubt that the TS590SG has   very good transmitter IMD  performance, its a 12 volt radio.

The TS590SG is a good radio for value for money considering the performance that it delivers. Icom, Yaesu  or for that matter nobody else has a transceiver with such good
performance for the  price. All of Yaesu and Icoms radios that price range really have poor receiver and transmitter performance.  They must think that hams like paying a lot of money for new radio models with crap performance both on TX and RX.

Maybe one of these days Kenwood will offer a radio with good TX  IMD performance.


Well, the Sherwood numbers are out for the 590SG and they're pretty impressive for it's class.

Dynamic Range: 104db @ 20K spacing and 92db @ 2K spacing.

This, along with a relatively clean transmitter for under $2K makes this quite a bang for buck rig.

Looks like the I & Y boys have some catching up to do.

I'm just waiting for a $2K rig to come out with a built in panadapter / scope feature that you can directly plug in an external monitor into the radio without having to perform any RTL/SDR type hacks. I'm not going to spend $5-10K just to get a radio with this feature.
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K9MHZ
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« Reply #19 on: January 09, 2015, 05:54:17 AM »

Just curious what you're using for "good TX IMD performance" numbers?
« Last Edit: January 09, 2015, 06:01:15 AM by K9MHZ » Logged
W8JX
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« Reply #20 on: January 09, 2015, 11:30:48 AM »

Just curious what you're using for "good TX IMD performance" numbers?

I think it is a issue that is greatly over played by those that are bored and trying to stir pot on something and look "knowledgeable" .  As I said before a bigger problem is over driven audio and over driven amps that make a far bigger "mess" of things and even a "clean" rig can go to crap when over driven. Also the "problem" with IMD rating is that they are not real world because we do not talk in continuous single tones of fixed amplitude and real world IMD is likely far less than lab tested results as average power is much lower. It would be interesting to see IMD tests for rigs at 50 watts vs 100 too as most use much less than 100 watts to PROPERLY drive a amp. About only amp that really needs 100 watts drive is one with a pair of 3-500's which will not be over driven with 100 watts.
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--------------------------------------
You can embrace new technology and change with it or cling tightly to old technology and fall further behind everyday....
K9MHZ
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Posts: 608




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« Reply #21 on: January 18, 2015, 08:56:10 PM »

I'm just waiting for a $2K rig to come out with a built in panadapter / scope feature that you can directly plug in an external monitor into the radio without having to perform any RTL/SDR type hacks.

That's got to be next, with everything going to visuals and screens these days. I'm actually a little surprised that Kenwood didn't do that with the SG.  Maybe it's a little early yet, who knows?  Icom put a screen on their 9100/7410, but the scope feature is really crude, so for under $2K, it's still sparse.  Hopefully for not too much longer, though.   

I don't own any Elecraft gear, but just wondering what a K4 might look like?  My guess is including a screen.  They won't be able to keep up current K3-type configurations at their pricing.

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W9CW
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« Reply #22 on: January 19, 2015, 12:41:53 PM »

As to Zenki's comment regarding Kenwood and decent 3rd Order IMD... Refer to Radcom's June 2013 review of the TS-990S.

The transmit 3rd Order IMD is not too bad (except for a few bands) at rated output power (200W).  Certainly could be better for a +50VDC solid-state final, but it's better than many other transceivers.  And, remember, this was a very early production sample, so the current numbers could be better.

1.8MHz -32dB
3.5MHz -40dB
7.0MHz -42dB
10MHz -50dB
14MHz -42dB
18MHz -46dB
21MHz -35dB
24MHz -31dB
28MHz -31dB
50MHz -33dB

As to the 590SG's split conversion design, it's the same design as used in the original TS-590S.  There are really few tangible receiver-chain design differences between the SG and the S.  The primary differences is the redesign of the 1st mixer, the DSP-controlled AGC, and the transmitter's ALC.  Yes, the SG has a different display board/CPU to support CW decoding, but who needs it?  I've never seen a decoding algorithm yet that truly works well with different fists and bug users.  When you're trying to hit a target price point, some compromises are reality, and designing the receiver for the best dynamic range for the most-often-used bands, especially the contest bands, actually makes some logical sense.

I have both the original 590S and the 990S.  The 990S uses down-conversion on all bands for its main receiver, and its sub-receiver uses the 590S receiver design.  I really can't see significant qualitative differences in performance when "push comes to shove" compared to the 590's up-conversion bands during contests.  I'm sure they are there, but I can't hear them.  But, then again, I don't have monster Yagis on a 100 ft. tower!

Over-driven audio is a serious problem.  I know of a few local hams who really need to monitor their output with a scope and seriously keep an eye on the Christmas tree to eliminate flat-topping.  Every ham running SSB should be monitoring their output with a scope to ensure flat-topping doesn't occur.   Our bands would be better off for it!
« Last Edit: January 19, 2015, 12:52:10 PM by W9CW » Logged
K9MHZ
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Posts: 608




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« Reply #23 on: January 20, 2015, 06:03:07 AM »

As to the 590SG's split conversion design......When you're trying to hit a target price point, some compromises are reality, and designing the receiver for the best dynamic range for the most-often-used bands, especially the contest bands, actually makes some logical sense.

Don't have one, so asking probably way too many dumb questions...... Does that receiver down-converting section include those older, traditional 1st, 2nd, 3rd etc harmonic bands that would be more easily accommodated into a single string, rather than the "weird" WARC bands' operating freqs that would require a single, dedicated converting section for each of those bands?

Since you mentioned it, is overdriven audio something that's particularly chronic with the Kenwoods for some reason?

Thanks.



 
« Last Edit: January 20, 2015, 06:07:45 AM by K9MHZ » Logged
W9CW
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Posts: 121




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« Reply #24 on: January 20, 2015, 06:26:55 AM »

The TS-590S and TS-590SG use down-conversion for the following bands: 160, 80, 40, 20, and 15M.  Up-conversion is used on the WARC bands and 10M.

I mentioned over-driven audio as it applies to ALL brands of transceivers on HF. It's not a fault of the rig, but the operator.  We are not talking about ALC Overshoot here, but setting the Mic gain too high.  Regularly, I hear a local op in this area who constantly over-drives his K3/KPA500 combo.  His signal is W I D E (measured on a Rigol spectrum analyzer), and you can hear buckshot up and down the band from his center frequency.   
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PA1ZP
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« Reply #25 on: January 20, 2015, 10:23:44 AM »

Hi

Actualy the Kenwood TS590S is 1 of the hardest rigs to get very wide in TX SSB.
The very agressive ALC attacks very fast.
If you do not play in the factory settings menu 23 / 24 this rig is not bad at all.
A simple FT857 or IC7410 are very easy to overdrive and get very wide.

Even now after the ALC mod was done in my TS 590 it is very hard to overdrive in SSB, ALC still attacks very fast.

It is so easy for me to overdrive the FT857D I have, it is even difficult not to overdrive this FT857D , the TS590 stays much more civilised hihi.

73 Jos
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W9CW
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« Reply #26 on: January 20, 2015, 10:44:23 AM »

Gentlemen,

I did not single out, imply, or state, the TS-590S is easily over-driven or wide in SSB.  Quite the contrary... I simply stated that there are a significant number of hams who over-drive their rigs on SSB.  This can apply to any, and all, rigs manufactured today, and yesteryear as well.  ALL rigs - regardless of manufacturer - can, and are, over-driven by operators daily who simply don't understand how to properly set their mic gain, or don't care.  In many cases unfortunately, the latter may be true.  All you have to do is listen, especially on 80, 40, and 20.

IMO... Every op who operates SSB should be using a monitor scope to monitor his or her transmit SSB signal.  Flat-topping and over-driving (and the resultant splattering and buckshot) are easily seen if you use a monitor scope in the RF loop, either between your exciter and linear, or observing the trapezoidal waveform output of the linear.  Depending on the rig, one can maintain voice peaks in the ALC range, and still be flat-topping on a monitor scope due to the ALC's design and response time.

It would be a real eye-opener if one of the online sites or QST did a survey on how many ops use a monitor scope on SSB.  I'll bet it's less than 20%, or even lower.   You can have an exciter with fantastic 3rd order IMD specs, but the op behind the mic can ruin it all, and make the bands a less happy place for all of us.

73
Don W9CW
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K9MHZ
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Posts: 608




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« Reply #27 on: January 20, 2015, 06:31:12 PM »

Yep, we're down with all of that.  Just looked a little curious in your 990S/590S post above.  I just did the exact same thing in another thread about the IC-7700.....must be that digital translation.  
« Last Edit: January 20, 2015, 06:47:28 PM by K9MHZ » Logged
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