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Author Topic: What is the best transceiver for my situation?  (Read 863 times)
K5NT
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Posts: 25




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« on: August 14, 2004, 09:57:28 AM »

I have just moved to a restricted community and am limited to attic antennas.  I put up an Alpha Delta DX-EE, which works pretty well.  There is room for a loop, which I may add later.

My main rig is a Ten-Tec Corsair II.  I am wondering if the newer transceivers offer features that would help me get the best performance in this situation.  The Corsair has crystal filters and a few other bells and whistles, but lacks DSP and most of the more modern features.  I work mostly CW and PSK-31, but occasionally get on SSB.

If modern technology would help me out, I will make the investment.  The Icom IC-7800 is out of the question due to cost, but just about anything else would be affordable. Receiver performance is the most important.  Good QSK is desirable.

I am open to any suggestions, and all advice will be greatly appreciated.  There are too many options for me to make an intelligent choice without outside assistance.

73,

Dave, K5NT
Richmond, VA

 

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W7DJM
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Posts: 1




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« Reply #1 on: August 14, 2004, 12:24:21 PM »

I don't know, but I recently bought a TS-570 Kenwood, and am not the least impressed with the noise reduction "ability" of the thing.

I just got done screwing away 1400 on a used MK-V Field, and it does do pretty well in that regard.

The noise blanker on my old IC-735, with a clear speech speaker, or a Timewave DSP-9 does about as well as the TS-570 if you can stand to listen to the distorted audio.
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AA4PB
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Posts: 12891




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« Reply #2 on: August 14, 2004, 04:10:44 PM »

I don't think features like DSP will make any significant difference in your ability to cope with an indoor antenna. You are already doing what will provide the bigest benefit with weak signals - CW and PSK31.
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K5NT
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Posts: 25




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« Reply #3 on: August 14, 2004, 09:30:35 PM »

I guess what I am really asking is this:  Since I can't have a decent antenna setup, which transceiver does the best job of reducing QRN and QRM, and then helping me to pull signals out of the noise that remains?

K5NT

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K7VO
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Posts: 1010




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« Reply #4 on: August 15, 2004, 12:48:15 AM »

The Ten Tec Corsair put up outstanding receiver ARRL lab test numbers even by today's standards.  I don't think buying a new radio will improve the receiver.  For adjacent channel QRM I really believe the crystal filters in your Corsair will do as well as any DSP out there.  If you don't have a full set of filters for your Corsair I'd start by adding them.

For QRN I think you can do almost as well with a good outboard audio DSP as you can with a modern IF DSP.  Find a good used JPS NIR-12 or a Timewave DSP-599zx.  Those do an outstanding job.

If you want to look at the latest and greatest technology I'm afraid I have very little first hand experience.  The Ten Tec Orion seems quite impressive and Ten Tec has a 30 day unconditional money back guarantee.  If it isn't an improvement over your old Corsair you can send it back and only lose shipping costs.  Besides, if you're a CW operator you've been spoiled by Ten Tec's wonderful QSK and you will not like a Japanese rig nearly as well Smiley

73,
Caity
K7VO
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AA4PB
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Posts: 12891




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« Reply #5 on: August 15, 2004, 12:22:08 PM »

If by QRN you mean power line noise and such picked up by your attic antenna, I still doubt that DSP is going to make a significant improvement. The several different DSP units I've tried do a decent job of reducing "white noise" (the fairly constant hiss you hear in the background) but don't do much for impulse noise like power line and static crashes. Even at that you say you spend most of your time on CW and PSK31 so DSP noise filters won't help you there. On PSK31 you are already using a very powerful DSP in the software running on your computer.

Probably the best you can do on CW to minimize noise and pull out the weak signals is to use a narrow crystal filter in the IF of your Corsair.

Unfortunately there just isn't any "magic bullet" radio that will make your attic antenna perform like a good outdoor antenna. Getting a more expensive radio may give you added features and "bells and whistles" but I seriously doubt that any will provide a significant improvement over your Corsair in terms of the ability to communicate using a less than ideal antenna.

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WB2WIK
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Posts: 20611




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« Reply #6 on: August 15, 2004, 07:38:19 PM »

The Corsair's great, and I doubt you're going to do better...although the Omni VI and Orion might be *slightly* better (to the tune of 1-2 dB), as might the IC-7800 or some very new generation technology stuff.

Problem is all with the antenna.  You can connect a million dollars' worth of gear to a dipole, and you still have a dipole.  You can connect $150 worth of old junk to a beam on a tower, and you'll do far better, usually.

Can you get *any part* of your antenna outdoors, past the snoopy noses of the homeowner's association, or whatever?

I did an experiment for an old friend back east years ago: He had a great "fan dipole" in his attic at about 30' above ground, and it loaded up perfectly but wasn't working much DX.  I laid a resonant 20m dipole on his balcony, insulated by his XYL's hair curlers (about 2" above each surface), and ran the coax in through the patio doors.  I bet him a dinner that my $2 dipole would work better.

It did.  And not just better.  He worked 3Y5X with it on the second call, after having made 200 calls with his indoor Alpha-Delta dipole in his attic just minutes earlier, the same day.

"Outside" works better, unless your home is made of cardboard.

WB2WIK/6
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W1VT
Member

Posts: 841




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« Reply #7 on: August 26, 2004, 09:48:24 AM »

Perhaps the best solution is a multichannel software defined radio.

http://www.arrl.org/tis/info/sdr.html

Each channel can be connected to a separate antenna  and software can be written to provide active noise cancellation between any combination of antennas for
the best signal to noise ratio based on known characteristics of the desired signals.

Best of all, you can prove that homebrewing isn't dead, just different today.
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N0TONE
Member

Posts: 173




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« Reply #8 on: December 03, 2004, 12:42:49 PM »

Best thing is to get the antenna outside.  Even in a deed restricted area, it is possible.  One of my grandsons runs a coax up, hidden behind a downspout, to the roof.  He snakes gray-insulated #22 wire under the shingles, in whatever configuration he wants.  He prefers loops.  

Another technique I've seen used is to use RG-8X as a feeder, running it right on the siding of the building.  Looks just like CATV coax, and CATV coax going up the side of a building is pretty normal these days.

As far as rigs, I would not, at this time, condemn myself to being stuck with the internal DSP of any radio.  Get a rig that is known for its good analog noise blanker, and add the Clear Speech speaker, which is known as a good outboard DSP.  A hint on noise blankers - if they don't have at least a sensitivity adjustment, they're no good.  The aforementioned IC-735 is one such adjustable NB.  The radio otherwise has a fairly marginal receiver, but in your constricted antenna situation, you don't have much to worry about with regard to IMD.

AM
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K8DIT
Member

Posts: 14




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« Reply #9 on: January 23, 2005, 09:20:59 AM »

Your antenna is going to be your limiting factor there.
You have the best rig for what you like to do. Devising a listening antenna, like a small rec'v loop will buy you more access to the hf band of choice, in terms of noise reduction/signal acquisition.
Upgrading to any audio DSP device is frought with peril. Nothing will buy you better selectivity than your IF chain and the native crystal filtering.
Upgrading rigs will get you more in the way of processor controlled conveniences and perhaps a way to control the rig via your computer. Only the Jupiter will give you any alternative to the paradigm you've described, by giving you IF DSP which is a brave new world only you can decide is right for you. I like mine but still want access to my Omni VI/opt1 from time to time, just because I like it. The difference between the CorsairII and the Omni VI is the processor control of the frequency changing domain, negating the PTO, using an optical encoder instead, which factors in the whole frequency and bandswtching changing scheme. The difference between the Corsair series and the Jupiter are much more dramatic. As many people like as not the whole SDR aspect and think IF DSP is cool. If you are handy with desktop PCs then you might want to try one. The only thing I havent mentioned is that when you hand over the entire radio to computer controlled devices, rf getting back into the radio becomes something of an issue, and then only finessing it gone will allow the radio to function normally. The Condominium/antenna limited places may not be the best venue to attempt this.
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