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Big Question: Why do most Ham radio's sound like crap on AM

R

razor

Member
Feb 27, 2006
27
0
11
I know it may not be appropriate but I guess I am guilty. I have a Yaesu FT1000 mk5 that I have tried to transmit on any frequency on AM and it sounds distorted. This is after turning the pwr to various levels of output. I have turned the mic gain down, and the processor does not work anyway on AM. I understand most other modern Ham radio rigs are like this. Any suggestions what to do. I'm sure this may have been kicked around before. Thanks for any help.

John
W5HG
 

Because ham rigs are using a low level AM modulation, they are not truly AM, more like a double-sideband. Or at least that's the way it was explained to me.

You can get a ham rig to sound good on AM, but don't expect it to operate like a CB.
 
I was also told that you can get certain filters such as the AM filter for my ft100D and it would help alot but then he said it still would not sound real good. Funny that a $2000 dollar radio that is all mode wont sound good on the AM mode. Why include it if it sounds like crap... oh well. . .
 
181 said:
Because ham rigs are using a low level AM modulation, they are not truly AM, more like a double-sideband. Or at least that's the way it was explained to me.

You can get a ham rig to sound good on AM, but don't expect it to operate like a CB.
Click to expand...

Not quite true. Low level modulation has nothing to do with what percentage of modulation there is. A lot of guys think that is the case.It simply means the the modulation is applied to a stage before the final power amp.It is modulated at a lower RF level than the final.Low level modulation can sound just as well as high level and is used because it allows for a much smaller audio amplifier (modulator) followed by linear RF stages whereas a high level modulated rig,typically a plate modulated tybe type rig, would require nearly 100 watts of audio just to modulate a 100 watt transmitter.

As for being like double sideband, that is technically what AM is,double sideband-full carrier.There is such thing as double sideband-supressed carrier which is just like running both sidebands at the same time which cannot be received when listening to AM.Then there is double sideband-reduced carrier which is more often used in older tube rigs with what is called screen (scream :D ) modulation or carrier controlled modulation and that can be understood on an AM rig.That is what my old Heath DX-60 has.It is similar to the idea of running a low dead key and then seeing lots of "swing" when you talk.

One of the reasons HF sets have poor audio on AM is the fact that there seems to be a "sweet spot" to setting them up.If it does not have the right combo of audio level,carrier level, etc. then they can be pretty bad.Also many folks compare them to jacked up CB's that are loud and appear clean to the ear but are actually dirty on a spectrum analyzer.In order to be legal the levels are kept down to what some folks would call poor quality.For the most part an HF rig can sound good on AM but it is generally not a switch-mode-and-go sort of thing.With so little HF AM operation there seems to be little chance of change in the future.Remember these rigs were not built to please the loud and proud CB'ers. ;)
 
most modern CBs use low-level modulation, right?

I was just wondering if the general modern ham rig can achieve a classic 100% balanced modulation?

Onces like the Yeasu 857D or Icom 706MKIIG, and others in the class?
 
I have done AM on 40 Meters with my IC706 MKIIG's and everybody said it sounded pretty good. I am not partial to any particular rig, but the Icom *seems* to come closer to *real* AM sound-wise. I have also listened to them as well, and if they were set up right, it was hard to tell the difference. I haven't done any "homework" on it like QRN, I am just going on
the results I got. Not to throw off on any particular rig, but the
Yaesu and Kenwoods sounded pretty bad (at least the ones I heard).


73
 
I agree with CWM that the 706mkiig is a good performer on AM.

Interesting thing with my Icom 746Pro...I have never been able to achieve 100% modulation with it. However, it sounds just fantastic on the air. That did take some setting up though. On the discussion of Double Side Band. The Icom 746Pro uses true DSB with carrier. Many if not most ham rigs use a carrier with just one sideband. That certainly contributes to the "poor" sound on AM.
 
Good point Mole. I forgot to mention about the carrier and ONE sideband issue,the family was waiting at the supper table for me to finish posting. :oops: While it is certainly fine for communications purposes and uses narrower bandwidth it does not lend itself to long ragchews with that nice pleasent and full audio. There are a couple fellows that check into the 80m AM Net on 3735 here on Sunday mornings that run Yaesu FT-847's and they sound really good on AM.I am told my FT-857 sound pretty good also after I turned off the TX DSP and TX audio filters etc. and just ran normal straight audio.My AM station is the old DX-60B tube transmitter with a scream modulated 6146B final.The microphone is a Sennheiser MD-421 with built in EQ.I am told by fellow broadcast engineers that I have full broadcast quality audio. :D :D :D Now all I need is something more than the 50 watts peak that I have. :?
 
I know the Yaesu's are not real good for AM. My 1000mp sounds fairly good when I turn the carrier way down. it sounds good and clear but it seems when I raise my voice alittle my voice distorts some. I guess like you said , most CBers like the pwr mike sound and that includes me too and ham radio's just don't cut it most of the time. You can fiddle with and make it talk but not like a radio built for AM. I went ahead and bought a Yaesu FT101E and use a modified D-104 and it sounds great but its a shame the other modern amatuer rigs don't sound as good on AM as the Cobras, galaxy's and so on. But they do GREAT on SSB. I just read a email from a elmer friend of mine and he said the 6 kHz AM filter will make a huge difference in the transmit audio. I may give it a try but if it doesn't work , I have been wanting to buy a S9 or a 95T anyway. I appreciate the comments.

John
 
Hey there..

As far as i have been told..
My 706 MKIIG does really well on AM..
My IC-7000 gets even better results on AM..

i am more conserned with SSB and FM..
been many many years since i perfered am lol

Later
 
Great, I heard the 706 was pretty good also.....Check in on some of the AM nets on 80 meters and see what they tell you. Don't tell them its a 706 until you get ready to get sign off. See what there initial response is.....

I guess they are a little picky up there...
 
I am a "casual AM'er" so I am not in a hurry to buy a plate modulated rig and a boatanchor receiver in order to do the mode. I got rid of all the back-breaking stuff YEARS ago and haven't looked back! :LOL: Many years I had an AM mobile called a Lettine 240 and a converter on the receiver. The plate was supplied with a 650 volt dynamotor. Cable from the batteries (yes, plural!) was about the size of your thumb into the trunk of the Chevy. Master Mobile 75 Meter (remember them?) "bugcatcher" on the trunk. Played with a lot of BC 610's, Vikings, and Globe Kings, Globe Trotters and the like.

Then we went to sideband and the rigs got smaller and smaller, then smaller still. I couldn't believe the Kenwood TS-50 when it came out! HAD to have it. Had already gotten a Yaesu 757 which was like a Cadillac compared to the boatanchors. That signalled the death of the boatanchors for me. Out went the AM transmitters, out went the old Hammerlund SP 600. And I got used to not having to strain while totin' them heavy things! :LOL: To the older hams, that was an outrage, sacrilege! :p No more would I gasp for breath while struggling up and down stairs from the shack!

I then discovered that my 706 would do decent--not perfect but decent--AM and I could QSO with the guys on 7290
reasonably well. Just don't tell 'em what I'm running--unless they ask! I used to listen to this guy in Florida that was, to me, the ultimate in an AM station! Deep voice with that announcer's timbre, definitely plate modulated transmitter, and a LOUD signal ( I forgot his call). Almost HI FI audio except during selective fading. Loved to listen to him. I wouldn't call him because I felt sort of humbled at the thought of my puny little 40 watts! :LOL: Almost like he'd be insulted ( doubt it--seems like a really nice fellow). Like---How DARE you call me with that, that, that----thing you're using!

But I am happy with my 706s. I am not likely to go back to the old glowing tubes and the era of ancient modulation. Only once in a while, I will get on AM for nostalgia's sake! It IS fun. OTH, I could get the bug and see those old filaments warming up the wintertime shack! Ya never know!! 8) So long as I have somebody I can talk into totin' that back-breaking stuff into the shack!!!

73

CWM
 

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