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Author Topic: Best HF receiver with lowest noise floor  (Read 24981 times)
KD7RDZI2
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Posts: 432




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« Reply #15 on: January 02, 2017, 11:35:43 AM »

I also don't understand (or believe) the ole', "radio A can clearly hear signals that radio B doesn't even know are there". One of those radios is busted.
N4UE

I agree. Even cheap portables (Degen DE1103, Redsun RP2100, Tecsun PL660) do hear quite the same of tabletops. They have plenty of sensitivity just as super expensive transceivers. The main drawback in portables is the front-end. Bandpass filters usually are non existent or poor at best. When connected to big arial you hear a mess, but if you use RF bandpass filters or a good preselector you cannot hear much difference between a portable a tabletop, unless during a CQWWCW contest. What I cannot understand in the Ten-Tec 340 test is the extremely poor figures in the dynamic range and 100kHz Blocking published in the http://www.sherweng.com/table.html come on it cannot be worse than a RTL stick!
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K1VCT
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« Reply #16 on: January 02, 2017, 02:49:03 PM »

Totally agree that even the cheapest radio will generally "hear" and generally have a sufficiently low noise floor that it becomes a non-issue when other sources of noise are present.

I've personally had good results with the TimeWave ANC-4, but I've heard lots of good about the MFJ unit as well (can that be??!!).  There are a few online pages about easy mods to the MFJ, which seem to favor that unit over the TmeWave for that reason.

I dunno.  Just a thought.  I've got nasty noise here in the house, source yet to be determined, but the external (roof mounted) vertical has a good six S-Units less noise.   The ANC-4 can be set to phase out almost all of it.
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HFCRUSR
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« Reply #17 on: January 02, 2017, 04:51:58 PM »

+1 the ANC-4. I run my receivers through an AlphaDelta 4-way coax switch to a Wellbrook ALA1530s+ up on my roof. The loop is supposed to ignore a lot of electrical RFI but it isn't perfect (likely because I have it up 50' off the dirt), hence the deployment of the ANC-4. I have the ANC-4 running on another AD two-way coax switch with my scanner, to the D130j on the roof, so it uses that antenna as noise pickup for stuff beyond my QTH. The ANC-4 knocks out a ton of RFI the loop suffers, and when I work that unit with the receivers' NBs, NRs, and even in some instances, a little reverse gain and/or ATT., I can isolate all of the noise as if it were squelched while still getting the desired signals. It takes a little coordinating effort though Tongue
« Last Edit: January 02, 2017, 05:01:06 PM by HFCRUSR » Logged

Not a ham, but an avid hobbyist in HF world. All things, short of transmit happen in this shack.
AUSSIE
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Posts: 51




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« Reply #18 on: January 03, 2017, 04:15:04 AM »

When it comes to receivers they all perform different since i been the hobby for over 35 years never had a portable perform same as a desktop even with the same antenna in fact yesterday i was listening to 5643 usb auckland hf aircraft on my Icom R75 aircraft and ground controller was cleari switched receiver Grundig Satellit 800 could bearly hear the aircraft ground controller was clear maybe when it comes to listening to shortwave radio stations both desktop and portable will be very close as for the 2 wellbrook loops mine are in the garage not being used.

Regards Lino.
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W8JX
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« Reply #19 on: January 03, 2017, 07:30:36 AM »

Quote
"I also don't understand (or believe) the ole', "radio A can clearly hear signals that radio B doesn't even know are there". One of those radios is busted.
SMH.....ha ha"
Yessir, and I  wonder by what mechanism all 1950s Collins military receivers are said to hear more on the AM BCB than modern radios?

Why do so many people believe this crap???  

I think it is because a lot of modern HF rig that cover BCB have there receivers padded with attenuation of 20 db or more on that band. 
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--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
K0OD
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Posts: 3030




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« Reply #20 on: January 03, 2017, 01:12:19 PM »

True about the front end attenuators on many receivers.

Was curious so I flipped on my old analog TS-850 which has one of those 20dB BCB pads. Still AM stations were deafeningly loud even with the AF gain set on 2 (out of 10). So lack of gain isn't a problem with hearing weak BCB stuff with any kind of reasonable antenna. I'd risk blowing out the Kenwood's speaker and my eardrums if I turned up the AF to seven or eight.

Yes, many modders remove those attenuators but I've never seen a need. Also I figure that Kenwood engineers know more about the 850 than I do. 
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VA3VF
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Posts: 2953




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« Reply #21 on: January 04, 2017, 07:35:22 PM »

The pad is there for a reason, and that reason makes most hamradio transceivers not suitable for AM BCB/NDB dxing, which is why some people remove the pad. It works for some people, but not for all. In your case, based on what you described, removing the pad would likely not be a good idea.

By the way, the 850 is very popular with LF experimenters, so it does have something else that other hamradio transceivers don't. Keep it, you never know where your radio interest might land you next.

73 de Vince, VA3VF


Yes, many modders remove those attenuators but I've never seen a need. Also I figure that Kenwood engineers know more about the 850 than I do. 
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K0OD
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Posts: 3030




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« Reply #22 on: January 05, 2017, 09:32:04 AM »

There's nothing remarkable about the longwave performance of the 25-year old Kenwood TS-850. Yes, I know a few SWLs say there is. Probably SWLs with 850s to sell! 

How do I know about the 850? Because I own one, and several other longwave-capable receivers. My preference is my Flex-5000 with Palomar VLF converter. The Flex has a panadaptor and a zillion modern features. I find its SAM mode very helpful for longwave reception. The Flex combo can tune down to 10 kHz versus about 100 kHz for the Kenwood.

But in terms of digging out weak signals, they're all about the same. On longwave especially, your enemy is EXTERNAL noise of various kinds and broadcast crud.
 
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VA3VF
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Posts: 2953




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« Reply #23 on: January 05, 2017, 09:46:07 AM »

>>>Probably SWLs with 850s to sell! 

That's a possibility. I wish I had done a screen capture of a guy's for sale ad some time ago. It was the best radio ever made bla bla bla. A couple of days latter, he placed a review of said radio. It sounded quite different than the one he sold.  Roll Eyes

>>>My preference is my Flex-5000 with Palomar VLF converter.

I believe most hard-core LF/VLF people use converter's, at least before SDRs.

73 de Vince, VA3VF


There's nothing remarkable about the longwave performance of the 25-year old Kenwood TS-850. Yes, I know a few SWLs say there is. Probably SWLs with 850s to sell! 

How do I know about the 850? Because I own one, and several other longwave-capable receivers. My preference is my Flex-5000 with Palomar VLF converter. The Flex has a panadaptor and a zillion modern features. I find its SAM mode very helpful for longwave reception. The Flex combo can tune down to 10 kHz versus about 100 kHz for the Kenwood.

But in terms of digging out weak signals, they're all about the same. On longwave especially, your enemy is EXTERNAL noise of various kinds and broadcast crud.
 
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K1DA
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Posts: 744




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« Reply #24 on: January 07, 2017, 11:36:33 AM »

A quiet receiver is  going to hear the noise better.
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W1JKA
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Posts: 2099




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« Reply #25 on: January 13, 2017, 08:40:47 AM »

ICOM 7200
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KD8IIC
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Posts: 788




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« Reply #26 on: February 20, 2017, 10:39:01 PM »

   Motorola built R390 Miltronix rebuild.
   The 10 watt HF CW beacon VHK3QQ in Bogata Columbia is a good test for a receiver station set up comparison.
   Professional and Military tube rigs are queit by design. The 'built-in' noise is low so as to not mask vy weak signals.
   Comparison here was with my Drake R7 and Drake TR7's on the same antenna. No signals were detected using them
   as modern and well designed as they are. I was fully quite amazed and ran the tests over again, also enlisted
   a friend across town and his TR7, no signal there as well.
   Bottom line is if you want to dig deep your rx needs to be very quiet.
   When I first started out I ran an IC R75 and was very happy with it until I got to operate mil radios using vacuum tubes.
   I am amazed at the difference between the two.
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KD8IIC
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« Reply #27 on: February 20, 2017, 10:42:21 PM »

   By the way, 10 watt beacon VH3QQ is found @ 7.082mHz with a choppy sounding Morse loop identifier.
   Have fun with it!  Smiley
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G4AON
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Posts: 1408




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« Reply #28 on: February 24, 2017, 02:29:12 PM »

There has only been a brief mention of antennas, yet it's the antenna that picks up the noise in the first place.

Recently I've been using a PA0RDT active antenna mounted in a corner of my garden, the improvement in signal to noise is often remarkable compared to my main antenna. I appreciate that not everyone will be in a position to mount an antenna several feet away from their house wiring, but it can make quite a difference.

There are plenty of web pages describing how to make a PA0RDT antenna, it's an easy weekend project using only 2 transistors and is only small. If you decide to try one, don't forget to use a feedline common mode choke and a good ground rod.

73 Dave
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KD8IIC
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« Reply #29 on: February 25, 2017, 04:28:38 PM »

  Hello Dave; The subject title is more about receivers than antennas.
  I have active receive loop antennas here as well as the pa0rdt, all work well enough and do a fine job.
  As for signal sensitivity, at least on the ham bands, I still get more gain from my transmitting antenna
  when it is tuned to resonance.
  The active antennas are however hard to beat during high atmospheric noise, provided there's a sufficient signal.
  Just my real world obsevations.
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