Too much power equals nasty audio.

Discussion in 'Survey Center' started by VE3VFI, Jul 31, 2016.

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  1. G3YRO

    G3YRO Ham Member QRZ Page

    I think the problem the OP is complaining about is down to the fact that most people use their Receivers with full gain, and rely on the AGC, which is effectively audio-derived. (after all, it's only then that the S Meter reads correctly).

    The problem is that if someone is very strong on SSB, even if they are using NO Compression/Processing, the background noise etc will come up between every slight pause, due to the receiver's AGC pumping (unless you can select a VERY slow time-constant setting, which very few rigs have.)

    SO then if you have a strong signal that is using a fair amount of Compression, it will be TWICE as bad.

    If that station was weak, then you wouldn't complain about their compression . . . in fact it might be what is making them readable!

    But you can't complain about someone using High Power and Compression . . . just because they are strong with YOU, doesn't necessarily mean they will be strong with some distant station they are trying to work. If you want to listen to them without your receiver making them sound worse (due to your AGC pumping), then simply turn the RF Gain down, or switch in some front-end attenuation.

    All of the above is presuming someone has a good transmission . . . of course, if you are using any form of tx audio processing, you should make sure you don't have distortion, or too much background noise or echo in the room, etc etc. (which of course, many people do - but that is a different issue)

    But funnily enough, on this issue, I have thought for some time that I might modify my TS-930S just like I did my R4A many years ago . . . I made the time-constant of the AGC in the "Fast" position what it originally was is in the "Slow" position . . . and made the "Slow" setting about 5 times longer. In that way, strong signals sound nice too, without having to adjust anything.

    Roger G3YRO
    Last edited: Jun 1, 2018
    K4AGO and N8VIL like this.
  2. KE0EYJ

    KE0EYJ Ham Member QRZ Page

    Old thread...

    Op lives in Aussieland. He's probably hearing ops from Indonesia who run their amps full-bore (sometimes Chinese amps at 2 or more kilowatts), along with high compression and some fans running in the shack, on top of the aircon -- because it's freaking 100 degrees plus humidity in there.

    Talk to said ops often, from here in Korea.
  3. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, I hadn't noticed that . . .

    I wonder why some people suddenly resurrect two year old threads ?

    (on many Forums Threads are normally locked if nobody posts for more than a few months, to stop that happening!)

    Roger G3YRO
  4. KP4SX

    KP4SX Premium Subscriber QRZ Page

    Its a complaint that never goes away. He stated it poorly, as many have pointed out.
  5. W1BR

    W1BR Premium Subscriber QRZ Page

    What difference does it make? Maybe for the classifieds, but some vintage topics may be of interest to newer Zed users.
  6. G3YRO

    G3YRO Ham Member QRZ Page

    Because people are often asking for help with a problem . . .

    So you offer advice, and wait to hear whether that WAS the cause of the problem.

    Then you notice that the post was 5 years ago ! So clearly they're not going to respond.

    Roger G3YRO
  7. W2WDX

    W2WDX Premium Subscriber QRZ Page

    As of late there has been a bit of jamming going on on the air. It does sound like a jet engine, I hear it often on 80m. Also, the OP may be hearing modern computer, wall wart and video hash noise from his house or the neighborhood. All this sometimes sits underneath stations signals on the air, and can create the effects the OP is mentioning. Older receivers can't discriminate, so it just gets mixed.

    However, there is also the issue of fade and other atmospherics that happen at solar minimums.

    Finally, there are guys out there running less than stellar amplifiers at full bore, some deep into the power compression curves, running non-linearly. "I have 1.2KW linear so that's where I run it" mentality. Instead of realizing most modern amps advertise power specs well into the power compression of the amplifier. And doing this will have an effect on modulation since the PEP portions of the signal is not being amplified with linearity. If you run power, you should always know where the power compression starts in the power response of the amplifier and operate below that; i.e. keep headroom. Many operators do not and you can hear it. This was not a problem years ago with older amplifiers with big stiff power supllies, but amplifiers are designed these days to not have any headroom, and in fact the max power specification includes the power compression point or beyond it. All to make small convenient desktop amps.
    K4AGO likes this.
  8. WD0BCT

    WD0BCT Premium Subscriber QRZ Page

    The requirement of ham radio to use as little power as necessary to maintain communications seems to go by the wayside when stations add the mega boomer amp to their radio arsenal. I've experienced the excessive power when listening on nets or some pile ups. Everyone is putting out similar signals until Biff Overdrive checks in and asks how his new amp sounds on his 4 element Yagi. I've heard some outrageously loud guys get ignored by a DX station every one is piling on to. Either the DX station is ignoring him purposefully or he has is gain antenna pointed in the wrong direction.

    I'm not saying power does not have it's place. It should be used carefully.
    K3RW likes this.
  9. W2WDX

    W2WDX Premium Subscriber QRZ Page

    I also think there is something to be said for the guy who can't afford and doesn't have a big amplifier, so when he gets on-air he feels inadequate, and has to show his size by driving his tool beyond what it can handle.

    Did I just say that ... without actually saying it? :eek:
  10. WD0BCT

    WD0BCT Premium Subscriber QRZ Page

    Quite a few people could easily afford "big amplifiers" but don't go there for a plethora of reasons. Being able to afford one is rarely one of the issues. Same applies to big antennas.
    WG7X likes this.

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