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Author Topic: Quietest Ham Transceiver with great sensitivity wanted  (Read 7302 times)
3CW
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« on: June 18, 2010, 07:43:51 AM »

I have an AOR AR8600 'scanner' that I use to listen to HF....

The receiver is incredibly quiet and allows for unbelievable distant station reception...adding to that, the audio is  very rich, clean sounding even though the unit is built for mobile use. I have been using it for years. It is just amazing.

I recently bought the Icom 7200....The receiver [relative to the AOR] is extremely noisy and annoying to the ear...even after all filter and DSP adjustments....I can't listen for more than 1 minute without becoming fatigued [ even when using a large external speaker from SweetSound].......It can't even pick up some of the stations the AOR does when side by side.

Can someone direct me to a HF transceiver that has a very sensitive but 'quiet' sounding receiver?

thanks in advance
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WB2WIK
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« Reply #1 on: June 18, 2010, 10:45:03 AM »

You'd probably like this one:

http://www.aorusa.com/aralpha.html

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3CW
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« Reply #2 on: June 18, 2010, 10:53:14 AM »

lol....ok, my bad....was hoping to find something for about 3,000.00 USD

thanks for that though!
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WB2WIK
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« Reply #3 on: June 18, 2010, 05:56:20 PM »

Probably not.

If you like the AOR receiver a lot and already have an IC-7200, you could use a T-R switch to transmit with the Icom and receive with the AOR.  That's a pretty cheap and simple solution and the only "complexity" is that you'd have to "SPOT" your transmitter to your receiver frequency; frankly, this isn't difficult at all for general operations -- it might be a bit time consuming for very rapid contesting where you're trying to make 100 QSOs an hour, but for general operating, "SPOTTING" only takes a few seconds and isn't hard.
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3CW
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« Reply #4 on: June 18, 2010, 08:32:06 PM »

I actually thought about that frequently over the past few months........That is probably the route I will take...I was just afraid of overloading the AOR receiver...

How does the T-R switch work?.....Never done that before, other than 30 years ago with seperate xmit and rec units and a big manual switch...[CW only]

I noticed the frequency readouts are not in synch ....how does one "spot"?

sorry for my stupidity...been out awhile....

even with the T-R switch, if the receiver is sitting directly atop the Icom, won't it still get overloaded somehow?

thanks for taking interest and the time to respond...very much appreciated...

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WB2WIK
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« Reply #5 on: June 19, 2010, 02:22:44 PM »

Use a coaxial relay.  They can have >60 dB isolation from the transmit to receive port on HF, and the receiver is very well protected by that, even if you run 1 kW output power or more.

Dow Key, Tohtsu, and many others make coaxial relays.

The receiver will not be damaged in any way. 

A simple way to "SPOT" is to key your transmitter without speaking, or for CW, turn the power all the way down and key it.  Zero beat the transmitter to the receiver and you're done.  Takes a couple of seconds.

This is too long for "contesting," but brief enough for most other types of operating.
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3CW
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« Reply #6 on: June 19, 2010, 03:59:34 PM »

thanks boss...thanks for all your help....
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N3OX
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« Reply #7 on: June 19, 2010, 11:06:58 PM »

I think it's not a very off-the-shelf solution in your particular case, but you might be able to use computer software to synchronize your radios.

I'm using Ham Radio Deluxe (http://www.ham-radio-deluxe.com/) and it is possible to set it up so that it keeps two radios in sync on the same frequency.

I think your AOR radio has the possibility of computer control (maybe it's only the MKII that does, not absolutely clear), but unfortunately HRD doesn't seem to support it.  I don't know if you could get it added (the commands seem well documented), or if you could add the commands yourself.

I think the effort and trial and error required might be more than you want to take on but I just wanted to let you know such a thing was possible.  It's pretty slick once it's set up... most of the time one radio instantaneously tracks the other so that it's just like you're turning both knobs exactly the same.  Sometimes if the computer gets a bit bogged down my slower-comms radio (Kenwood TS-440S) lags behind a bit but it will catch up in a fraction of a second.

Both of my radios are supported so it's just a matter of hooking them both up physically and checking a couple boxes in the "Synchronization" window.  I've never actually tried to add a whole new radio... but I believe such a thing is possible.

73
Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
3CW
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Posts: 20




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« Reply #8 on: June 20, 2010, 06:48:21 AM »

thanks for that info Dan....greatly appreciated....

I have a theory on these DSP receivers but maybe I'm wrong...I've been in since '76'..started with the old tube radios which seemed to have a much sweeter pleasing sound to the ears....I'm 48 and my hearing is good, but not sure if you ever heard the Icom 7200...I'm not bashing the company, I know hear they make great radios. But the contrast between the AOR and the 7200 is unbelievable...sorry for repeating it, but I can't even listen to the 7200....It just 'tires' me out immediately....Maybe all these fancier DSP radios sound like that....I guess thats the price to pay to reduce adjacent interference, I don't know...What I do know is the AOR is sweet...When I first got it, I was extremely disappointed...It was too quiet...It wasn't until I added one of those miracle antenna tuners then it came to life...oh well, sorry for the winded rambling post....

thanks again!
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WA9UAA
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« Reply #9 on: June 20, 2010, 09:40:53 AM »

Hi OM,
No real argument from me; but, when listening to the 7200 try reducing the RF gain or adding some attenuation and see if the signal quality improves. Depending upon what you are listening to; though, the filtering in the 7200 may be too narrow.
73,
Rob WA9UAA
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N3OX
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« Reply #10 on: June 20, 2010, 09:43:45 AM »

You might want to read this:

http://www.sherweng.com/documents/Dayton2007w.pdf

I don't think the problem is any fundamental limitation of DSP: it really seems to be the result of unintended consequences of new technology.  

I think it's probably that the people programming these things have been handed an incomplete specification for what they should do.  There are probably some aspects of old systems that just "came along for the ride" in those designs because of some analog behavior.  Some of those things probably have to be explicitly programmed in for the radios to perform satisfactorily.

DSP can do a lot more than old radios can but it only does exactly what you tell it Smiley
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
3CW
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Posts: 20




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« Reply #11 on: June 20, 2010, 10:32:48 AM »

great read N3OX..thanks..

I'll try that Rob, I know too narrowing of the filter makes it worse...

just wish I could ged rid of that high pitched hiss and noise and stuff ...lol

have a great Father's Day guys!

73, WA3YCW out!
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W9OY
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« Reply #12 on: June 28, 2010, 04:52:01 AM »

The quietest radios I've ever owned are the Flex line of radios 5K and 3K.  Very easy to listen to for hours without fatigue.  Also my TT Paragon was a quite radio

73  W9OY
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W8JI
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« Reply #13 on: July 04, 2010, 01:10:28 AM »

I find this all strange. I think we have a pathological science thing, like the tube audiophiles have, going on here.

At HF, all of the noise comes from the antenna and not from the radio circuits. The only exception is when using really narrow filters, some radios may have a little out of passband white noise.

Most complaints or compliments about "noise" are really about AGC charateristics. TenTec for example has a fairly high AGC threshold. It acts almost like a volume expander at low levels, meaning the gain does does not pump up between signal lapses. That gives the illusion of a "quiet receiver".

Other than bandwidth of filters, there is very little that really makes one receiver "quieter" than another at HF except how you set the gain (attenuators) and how the AGC is configured.  The single largest problem I see here with guest ops is they fail to use the attenuator pad on receivers when it is needed, and when they use a lower gain receiver they think "ooohh, this one is quiet". Reduce the gain in the hotter receiver and it is just as quiet.

Virtually every receiver at HF is external noise limited. I have not seen one yet that has any better S/N ratio than another if the same bandwidth filters are used, and if the operator knows how to use things like the gain controls, AGC settings, and attenuators. The sole exception is broadband white noise on some receivers that comes in after very narrow filters, but the brain or an audio filter can take care of that.

I don't know what receivers you folks all have, but every receiver here is limited by noise picked up from antennas and so they ALL have equal noise floors on HF. My 1941 HQ120 has the same noise floor as a K3 when they are hooked to the same antennas. I'd bet you are listening to AGC differences.

73 Tom
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KL7IPV
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« Reply #14 on: July 04, 2010, 10:39:39 PM »

In another time I would have suggested a TenTec, But with the computers we have, I now suggest a Flex Radio 1500. It is compact and runs about $1500. I don't have one but after running their demo on my laptop, that may be my next new radio.
Frank
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