Why is SSB receive audio poor at wide filters

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  • Updated 3 years ago
Its not a huge deal to me but my flex 6500 is really poor when listening to guys running eSSB. It picks up noise/hiss. Because of this I keep my filters under 3k typically even when listening to strong signals running wider than that.  I know its not just me as I hear guys on the bands complaining about it.  I have a friend dying to buy a 6500 but he wont do it until this improves.

I even notice this on AM broadcast. We have a local station that can be heard all over the country that is within about 5 miles of me broadcasting at 20k and I anything over 12k sounds bad.

Now to be fair I dont have rigs that will listen over 3.6k SSB so I personally cant compare but here this is common.

I know eSSB is strong signal only but this seems to be more of a flex issue based on the operators I have talked to.
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Rich McCabe

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Posted 3 years ago

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KC2QMA_John

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The wider the receive filter the more band noise you will hear particularly in high frequency audio range.

I can assure you the Flex has some of the finest audio reproduction available today and there is nothing wrong with your 6500. Listening at wide bandwidth takes a little getting used to but when band conditions are good you will be shocked at how good it can sound.
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Bill -VA3WTB

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You can play with the AGC-T to lesson the noise. It is true, the flex is so open on receive you can hear all the noise as you go wider.
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George Molnar, KF2T, Elmer

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You might also want to tailor the RX filter to better match your needs. A flat response (default) might not be what you want in this situation.
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Bill -VA3WTB

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Yes and, if going out wide, you can use the RX EQ to make things better.
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Carmine Iannace, W1EQX

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I think the issue has to do with the AGC adjustment. For AM and ESSB reception try to use either slow or medium AGC setting. I recall setting the slider around 30 or 35 in addition to slow or medium setting prevents the AGC from "sucking up" the background noise between words or other modulation. By the way, AM broadcasting high frequency response is limited to 10 kHz (20 kHz bandwidth) in the U.S. and 4.5 kHz (9 kHz bandwidth) elsewhere. 
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Carmine Iannace, W1EQX

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Also, many AM stations use very steep high frequency equalization to compensate for typical  analog car radio AM receivers that have very narrow filters. When you listen to such stations on a "high fidelity" receiver like the Flex with a wide bandwidth filter, such as 16 kHz, the audio may sound harsh and tinny due the large amount of high frequency EQ. Stations broadcasting in AM HD in the U.S. also limit their high frequency response to about 5 kHz to prevent intermodulation with the two wide and noisy HD sidebands above and below the carrier frequency. Hash from the AM digital sidebands is also much more noticeable in wide filter modes on the Flex. Not a problem with the Flex but more of an indication of the sad state of technical affairs in AM broadcasting.
(Edited)
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K1UO - Larry

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Its funny to hear people not buying the Flex because it doesn't "Sound Right" when in fact the Flex has , a measured,  flattest audio response across a wide range than any of the other receivers out there that they do like to listen to :-).  The good news is that the Flex includes tools to make the audio response as "distorted" as they like it :)
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Mike W9OJ

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It's like the LP vs CD debate.
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Ken - NM9P, Elmer

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Another thing to check...Do you have your AGC set to the fast or medium position? If AGC is on fast you will hear every little bit of noise in between the syllables of the other station. I almost always listen to sideband with AGC on medium setting and adjust the AGC-T until the noise begins to quiet down a little.
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W7NGA

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On strong-signal AM band signals, insure that the preamp is off. I was just about to write up a problem report when I noticed that the other panadapter listening to the 15-meter band was holding the preamp on +10db causing severe distortion on the AM signal. I really enjoy listening to AM and eSSB signals, pulling the filter skirts right up around the signal spectrum, and using the Bose Companion 2 Series III speakers directly off the powered-speaker output port. sounds bodacious!
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Barry N1EU

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I agree with Carmine - it's probably an AGC issue.  I also agree that the rx passband is ruler flat (I posted a thread celebrating this fact recently).  I'm not yet a big fan of the Flex 6K AGC.  For starters, it would be great if there was a visual indicator of the AGC Threshold overlaying the panadapter like PowerSDR has.  That's incredibly helpful!  Also, the "sweet spot" where gain starts falling off as you adjust AGC left and right with the mouse is too narrow and needs to provide more mouse adjustment area R/L.

73, Barry N1EU
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Rich McCabe

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I will play with it but I always run AGC in slow unless its a really weak signal. And honestly did not think about messing with AGC-T as I normally run it almost clear to the left when rag chewing using it as AF control.
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James Del Principe

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Why would anyone want to encourage ESSB in any event?    Ours is a communications method and not the local FM disk jockey. ESSB is a waste of spectrum.      
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Barry N1EU

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The Flex 6K is one of the best ESSB radios out there.  Your anti-ESSB agenda is tiresome.
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Michael - N5TGL

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Not specifically designed for this application?  I agree with Barry, it's one of the best, if not THE best ESSB radio on the market.  
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Ken - NM9P, Elmer

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There are many forms of communications technology that are not absolutely the most efficient use of the spectrum, yet many hams enjoy them for a variety of reasons...whether for nostalgia, love of high quality audio, pushing the state of the art, etc...

Once could ask the same spectrum efficiency questions about old style AM, or FM, or even D-Star.  They might not be the most efficient, spectrum-wise, but all serve a purpose....

D-Star fans are trying to push the envelope of a new technology that can link connections digitally via RF and Ethernet....

Free-DV takes a lot more power for a contact with far less fidelity than even the most narrow SSB signal.  But promises to bring some new ideas and possibilities which may or may not pan out on HF.

AM fans love both the nostalgia of vintage equipment, and the prospects of incorporating the newest technologies to obtain quality audio with simple equipment.

SSTV lovers will use 2.5 KHz of spectrum for 90-120 seconds to send a relatively low resolution picture across the globe when it wold be a lot easier simply to email a jpeg or gif file.  

ESSB lovers are getting amazing audio quality out of a bandwidth less than that taken up by even the most narrow full AM signals.

There are "modern" digital modes being used now that take up a lot more bandwidth and are less reliable than some other digital modes, but they still have a loyal set of followers.   

What do all these have in common?  They do it because they CAN...
Their practitioners ENJOY them.  

The neat thing with the FLEX, and especially the 6000 is that I have done ALL of them with one rig!  all the way from CW to D-Star and everything in between.  And it sounds GOOD doing it....IF I adjust it properly. And there will be more new modes in the future.

For one person or group to judge another group or individual's pursuits because there are more efficient modes available is unhelpful and against the amateur spirit.

I suppose we could mandate, in the interests of spectrum efficiency, that all hams be limited to either CW, PSK31, or JT-9.  We would be very efficient, then...But Ham Radio would be very boring.  

I believe that there is room for everyone....if we all respect one another.

Ken - NM9P
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KC2QMA_John

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I concur the 6000 series has the best TX&RX reproduction available today. As a recording engineer working in Nashville & New York City I am very particular about audio and the 6000 series is the best.

As far as the ESSB argument goes, ESSB is just another mode of operation like AM, FM, CW, SSB and so on and of course it is a Wide-Bandwidth mode so common courtesy must be used in this mode. Most people that work ESSB operate where there are no stations close by as to not cause QRM.

just my 2 cents.

73'KC2QMA
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KY6LA - Howard, Elmer

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As usual Ken you are the voice of reason.
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Rich McCabe

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Follow up.  My AGC is fine. As I said, eSSB really doesn't interest me and the fact I have heard other operators complaining about made me "ASSUME" that it was an issue. So I really did not attempt to resolve it.

The EQ settings in the 1k, 2K and 4k range totally fix the annoyance noise I was talking about. Just did not dawn on me this would be the case. Kind of stupid on my part now that I think about it. 

Guess I should have checked it out more. Like Abe Lincoln once said. You cant believe everything you read on the internet.

Thanks guys and 73,

Rich
kd0zv
(Edited)