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Author Topic: Flex power genious xl  (Read 5075 times)
K6BRN
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Posts: 1293




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« Reply #60 on: April 21, 2019, 07:49:56 PM »

Quote
he Rigol ( or Siglent) have 10KHz phase noise only down -88 dBc. The readings will be suspect at that low a level. HP analyzers are about -140 dBc at 10 KHz. Even my old (2001) HP8952E was -131 dBc at 10 KHz.

Ummmm.  this is amateur radio.  I have no problem working routinely at DANLs better than -100dB at 10 Hz RBW/VB on the DAS-815TG, which is fine for characterizing filters, checking signal generators for gross phase noise characteristics, checking circulators. measuring return loss.  The list is endless.  I'm NOT looking for a great deal of accuracy, at home.  I'm looking for GOOD accuracy and capability.

"Adequate" does quite a lot.  "Excellent" costs quite a lot.  In dollars, size or weight.  Take your pick.

BTW, I also use the Siglent SSA3000 series and no end of HP/Agilent/Keysight/etc. analyzers, from the 9000 series (current) to the old half-rack 8000 series and its options.  I use whatever works for my needs at the time, professional or amateur.  For home and amateur use, the Rigols and Siglents work fine and are light-years ahead of the old guard in terms of utility - a few lbs, the size of a small digital scope amd work pretty well.  I trot 'em out, use 'em an put 'em away.  No big deal.  Try THAT with an 8000.  (OMYGOSH!  It just crashed into a Buick and crushed it!)

Ack!  They have higher phase noise!  No kidding.  Need to move to a cavity oscillator or similar to do a LOT, LOT better.  Have fun.  There is a REASON why these old clunkers weighed so much.  And the Keysight 9000's are very good too, using more modern technology.  Brief-case sized.  Some compromises, some advantages.

Keep in mind that (regardless of phase noise) the AVERAGE noise levels are proportional to RBW and that Siglen't initial claims of far superior DANL was based on a 100 Hz RBW (Rigol) vs. 10 Hz RBW (Siglent).  Now Siglent is down to 1 Hz RBW (Rigols is down to 10 Hz).  What this specsmanship does not mention is that sweep time is inversely proportional to the SQUARE of RBW.  How much tine ya got?  A sweep that takes 1000 seconds at 10 Hz RBW will usually take 100,000 seconds at 1 Hz, for best accuracy.  10 Hz is about the minimum I've ever used at work.  1 Hz?  OK.  I'll just "let it run".

BTW... to the spec watchers out there... both the Rigol and Siglent products work just fine.  I find that the Siglent has a bigger, nicer screen.  But is also... bigger than the Rigol.  Take you pick.  Neither is a mistake for a home "lab".

P.S.  YES.  I've seen the EEVBlog tests and teardowns.  A lot has changed with both SAs.  Better RBW with the Rigols (and some HWupgrades) and better FW with the Siglents (was VERY bad when it 1st came out - buggy as heck - "How the heck does THIS work!  What DID I just do?").

Brian - K6BRN

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K6AER
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Posts: 5726




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« Reply #61 on: April 22, 2019, 08:16:44 AM »

Brian,

I am going to buy one of the Rigols units for every day use. The HP gear is getting fragile and my shoulder muscles are not what they use to be. How their service here in North America?
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K6BRN
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Posts: 1293




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« Reply #62 on: April 22, 2019, 08:52:45 AM »

Hello, Michael:

Never had to send mine in. (have two 'scopes and one spectrum analuzer by them)  But on-line questions, firmware, etc. is pretty easy, and TEquipment can also help with service returns, where needed.

Rigol DSA815-TG

https://www.rigolna.com/products/spectrum-analyzers/dsa800/

https://www.tequipment.net/search/?F_Keyword=dsa815tg

Suggest you also look at the Siglent SSA3021X

https://www.siglentamerica.com/spectrum-analyzers/ssa3000x-series-spectrum-analyzers/

http://www.saelig.com/category/siglent-spectrum-analyzers.htm

The second link is for Saelig - may be the only North Amarican Siglent vendor.  I've been using both the Rigol and Siglent units.  The Siglent has a snazzier screen and is bigger.  VERY nice.  Both Rigol and Siglent units work just fine (just don't expect perfection).

Make sure you get the Tracking Generator built-in.

Note that if you join EEVBlog and request a discount code, Saelig will usually knock off 10% or so from the price for Siglent equipment.

Have fun!

Brian - K6BRN

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AD5X
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Posts: 1623




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« Reply #63 on: April 22, 2019, 09:37:07 AM »

I had the Rigol for several years. An excellent SA/TG. I sold it and bought the Siglent after I did the Siglent review for QST. I liked the bigger screen and I found the Siglent a tad more user friendly, though this may have changed with time as both are always updating their firmware - which is easy to do. And yes - definitely make sure you get the tracking generator.

Phil - AD5X
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N4UE
Member

Posts: 907




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« Reply #64 on: April 22, 2019, 02:06:41 PM »

Hi Guys, I'm a true 'newbie' when it comes to SA/TGs.
I have the Rigol and enjoy using it.

Is the software upgradable? I thought it 'was what it was'. I believe mine is 2 years old....

Any thoughts to help this OT out?

thanks!

ron
N4UE
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If you're not the lead sled dog, the view never changes......
VK6HP
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Posts: 525




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« Reply #65 on: April 22, 2019, 06:31:13 PM »

Yes, the Rigol firmware is upgradable.  See: http://int.rigol.com/Support/SoftDownload/3

Looking at the release dates, you may already have the latest version.

I use a lot of very high-end test gear but in terms of bangs per buck, the Rigol SA/TG combination takes some beating. (I've not tried the Siglent). About the only thing I've occasionally missed is the ability to do tracking generator offsets, but that really is asking a lot for an entry level system.  All test equipment has limitations and part of the engineering approach is to be familiar with those.  I'm not *that* old but I'm still amazed at the capability of contemporary "low end" equipment, especially in the ham environment.

73, Peter.
« Last Edit: April 22, 2019, 06:45:48 PM by VK6HP » Logged
K6BRN
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Posts: 1293




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« Reply #66 on: April 22, 2019, 10:05:25 PM »

Peter (VK6HP):

Your QRZ page is an interesting read.  If you lived next door I'd be pestering you to look at your very extensive gear selection.  I'm sure we'd find some very interesting projects to work on.

Had to really laugh when I read this:

Quote
I've recently overhauled the Heathkit HR-10B that I built as a teenager (second shelf from the top in the picture). It is a terrible receiver in nearly all respects but great fun to use.

Awful IS the word for the HR-10B.  But... with its crystal calibrator and warm glow on a cold winter's night, it facinated me as I tuned the short wave broadcasts, ham bands and even CHU in Canada, on their old frequency from my then-QTH in Connecticut.  It was the first receiver I'd ever built.  Pure magic.  I finally gave it away a few years ago.  Just ran out of room and never used it.

Best Regards,

Brian - K6BRN
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VK6HP
Member

Posts: 525




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« Reply #67 on: April 23, 2019, 02:55:00 AM »

Brian,

I lost sight of the HR-10B for 40 years or so but, when re-discovered in the recesses of a family home, I felt motivated to resurrect it. Having owned one yourself, you'll understand that I am not exaggerating when I tell people about the difficulty of copying CW while living at the end of a rural mains feeder, with the attendant rapid voltage swings.  But it was fun and, when I got my first "proper" radio (a well-used FTDX401B), it was a truly transformational experience.

Anyway, maybe starting with something like an HR-10B makes us grasp the importance of the human in coaxing the best out of equipment, not to mention giving us a near zero-point for receiver performance evaluation Smiley

73, Peter.
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K6BRN
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Posts: 1293




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« Reply #68 on: April 23, 2019, 10:01:03 PM »

Quote
maybe starting with something like an HR-10B makes us grasp the importance of the human in coaxing the best out of equipment,

Hmmm.  I wonder if the HR-10B in on "Sherwood's List"?  Smiley

My first decent transceiver was a broken HW-101.  I was in heaven once I got it working.  It was a great sounding radio and using the RF gain, preselector and (optional) crystal filter, I could pretty much pull out any signal worth copying.  But the VFO was almost as "drifty" as the HR-10B, which I did not mind much until I started working RTTY and AMTOR.  THEN I had to "ride the knob" on the VFO to track the QSO.  Used an AEA AMT-1 I found at a flea market (no manual and no internet to look up how it worked - had to figure it out)  and had to design and build a low-voltage keying interface into the radio to support it.  Used high voltage BIPOLAR transistors, and it worked just fine.  

By the time I was able to buy a used Kenwood TS-440SAT, I thought THAT radio was the greatest.  But then realized my ears would ache after listening to it for a few hours.  Vary harsh, noisey audio.  Still have it, in fact.  The audio problem cleans up nicely with a CLRdsp attached.

So... dropping over after work for a lager, whisky or coffee?  I want a look at the KPA-1500 and HR-10B.  You DO have the DX-60B to go with it?  Smiley

Best Regards,

Brian - K6BRN
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VK6HP
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Posts: 525




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« Reply #69 on: April 25, 2019, 01:23:37 AM »

Brian,

Heathkits were not that common in Australia in the 70s and early 80s as I recall, perhaps because of a long supply chain and the strange tariffs in place at the time.  But I was mightily impressed with a friend's HW-101, mainly because it sounded great on CW and had all sorts of knobs to tweak.  I can well understand that it would be a revelation after an HR-10B.  Not sure about the Sherwood list, though - could you get the HR-10B to stay put long enough for the test signals to stay in the (admittedly barn door width) passband?

No DX-60 on a high school budget I'm afraid - just a homebrew transmitter using a 6BM8 and other parts gleaned as part of a B&W TV cannibalization. With a handful of donated crystals, it approached 10W output on 80m (on a good day), but the pea lamp glowed a lot less on 20m! Still, with the solar cycle of the day, life was pretty easy.  You can imagine, though, what a change the FTDX-401B brought.  I'm almost ashamed to mention that rig in what started out as an IMD thread: even if I had run the sweep tubes at 120W output (which I'm not sure I did), IM3 would have been about -(20-25) dB wrt tone, almost as bad as a one or two contemporary radios. About all I can plead in mitigation is that I did build a basic monitor scope and there was no obvious clipping.

I like the KPA1500 because it's well engineered and fits my requirements, although I do look forward to getting it operational in a pre-distortion environment.  Just now, it runs ridiculously de-rated (and clean) to meet Australian regulations.   However, I have tested it into a dummy load at full output, in various modes  for extended periods, and the published allowable duty cycle figures are achievable.  The only complaint might be that it won't be particularly quiet in e.g. RTTY and digital modes.  Still, there are various location options, including remote positioning and operation.  On SSB, though, it doesn't really break a sweat.

73, Peter.
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VK3BL
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Posts: 1789


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« Reply #70 on: April 25, 2019, 05:39:11 AM »

An SDR Play makes a fine substitute for a cheap spectrum analyser; the dynamic range is greater than 60dB and the accuracy is comparable at around 1dB.

It is also significantly cheaper.

If one doubts my statement, it is easy enough to verify if you research the ADC used in the device and its application notes; decoding QAM256 REQUIRES 1dB of resolution.

The only reason (for a Ham) to buy a cheap spec an is if it has a tracking generator IMHO.

73, Jarrad VK3BL
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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
K6BRN
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Posts: 1293




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« Reply #71 on: April 25, 2019, 09:35:56 PM »

Quote
An SDR Play makes a fine substitute for a cheap spectrum analyser; the dynamic range is greater than 60dB and the accuracy is comparable at around 1dB

Ahhhh...  no.  Not even close.  I have and use both.  A spectrum analyzer with TG is a tool that allows fast and easy checkout of many metrics, with reasonable accuracy and repeatability.  Even if its an "inexpensive" one.

An SDRplay is a fun "Kludge" made largely out of what I think is a DVB chipset intended for embedded applications.

One is a tool, the other is a toy.

If you have the opportunity to learn to use and apply a real spectrum analyzer / TG, you will REALLY appreciate it.

Brian - K6BRN


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K6BRN
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Posts: 1293




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« Reply #72 on: April 25, 2019, 10:13:03 PM »

Hi Peter (VK6HP)"

Quote
Heathkits were not that common in Australia in the 70s and early 80s as I recal

I wondered about that.  Always thought Heathkit was a U.S. phenomenon.

Regarding IMD - Glad your "Homebrew Transmitter" didn't destroy the world.  As for active linearization, step into that one carefully.  Done wrong, its a mess - and this is AMATEUR radio.

I've used many TWTAs (feed-forward passively linearized travelling wave tubes) and SSPAs in my career, and active feedback active linearization/equalization.  Without it, we had to "back off" the amps a lot more to get a clean signal, making them more inefficient in terms of power use vs. power output and mass.  In the ComSat business TX power x bandwidth = revenue.

But when active linearization went wrong, the signal usually became FUBAR, whereas the passive feed-forward networks just drifted and degraded a little over time.  So the active approach has to be done well in order NOT to become a big "part of the problem" (it's NOT forgiving) and it has to be monitored to detect when it goes "off the rails".  A lot less critical in amateur radio, but still a "Gotcha" most hams do not think about.  I'm generally not too concerned about IMD and run my amps backed off quite a bit at home.  But I do have an imaginary nightmare of thousands of hams trying to hook up their active linearizers and splattering entire bands into obiivion.  After all, many can't even connect and adjust an amps ALC correctly.  My fears on this are no doubt way too exaggerated - we'll just have to see how this evolves.  And if it works out (maybe a standard for feedback linearization is adopted and baked into amps and rigs), excellent!

Good Night!  Time to hit the sack over here.

Brian - K6BRN
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KD8MJR
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Posts: 5557




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« Reply #73 on: April 26, 2019, 07:41:37 PM »

Brian,

I am going to buy one of the Rigols units for every day use. The HP gear is getting fragile and my shoulder muscles are not what they use to be. How their service here in North America?

You would be better off buying a Siglent SSA3000 series than a Rigol.
Much better value for the money with the SSA3021x running around $1395 and it goes from 9Khz to 2Ghz.  Better yet it's almost like Siglent encourages you to hack the 3021x into a 3032X which goes up to 3.2Ghz and it unlocks all the optional pay to use features.  It took me about 15 minutes to do the hack and is pretty straight forward.  The equivalent Rigol which would be the DSA832 will set you back $3400 and the extra locked features will cost you extra $$.

The support for Siglent is excellent and Saelig, their US dealer also has excellent customer support.  BTW Saelig will even give you a discount if you ask for one on the phone, just say your an eevblog forum member.


73s
Rob

« Last Edit: April 26, 2019, 07:49:46 PM by KD8MJR » Logged

“A lie can travel half way around the world while the truth is putting on its shoes.”  (Mark Twain)
M0HCN
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Posts: 566




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« Reply #74 on: April 27, 2019, 10:31:33 AM »

Done wrong, its a mess - and this is AMATEUR radio.
Yep, had Cartesian feedback go pearshaped (fortunately into a dummy load, and I was trying to provoke it), but is is fairly easy to detect the problem and kill the output as the EVM goes thru the roof.

Adding logic to measure EVM and shut things down if it becomes excessive is fairly basic engineering. Having the logic keep an eye on I'Q -Q'I (A reasonable proxy for loop phase error) is trivial as you are probably using something like that to drive the phase correction anyway.

The other saving grace of a DUC/DDC radio in this scenario is that you can use the ADC to actually do transmitted spectrum measurement in realtime, you know how wide you are.

73 Dan.
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