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Author Topic: Suggestions for a good cheap HF base station?  (Read 1888 times)
G4JJP
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« on: November 14, 2005, 01:24:48 PM »

My Icom IC 706 is a great little radio, but I want something that has better hearing - something that will really pull the weak signals off the antenna.

So I am going to try to get a cheap, second hand base station transciever with EXCELLENT receiver.

It needs to be cheap, hence very second hand, and I would love to hear suggestions from the crew on Eham.....

Richard
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WB2WIK
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« Reply #1 on: November 14, 2005, 04:33:39 PM »

What is the antenna?

The IC-706 has more than enough sensitivity to keep up with the best "base station" transceiver ever made by anybody.  On HF, "sensitivity" is one of the very least important considerations, in terms of actually hearing signals.  Almost every other characteristic is more important -- again, in real-life terms of "hearing stations."

So, unless it's got a blown front end or first mixer, the IC-706's sensitivity wouldn't be the problem.  But other things about it might be the problem.

What kind of antenna(s) are you using?  I'd want to know more about that before recommending a different rig, mostly because some rigs excel at extremely strong-signal handling (such as you'll have with "big" antennas) better than others.

WB2WIK/6

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G4JJP
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« Reply #2 on: November 15, 2005, 12:54:37 AM »

At present, the antenna is a rather squashed closed loop in what approximates something like a rhomboid with the bottom leg only six feet from the ground, and the top leg only about 20 feet from the ground, fed from the top corner via the eaves of a three storey house.  My shack is in the loft.  I am experimenting with trying to get the best antenna in a rather cramped space, and thinking of changing to a sloped Windom.  I have to be fairly 'stealthy' because of neighbours.  I am in a town, and suffer quite a bit from rf noise.

My Icom 706 is a Mk 1 version, and also suffers from the lack of drive from the microphone on SSB. Glad to hear that it has good sensitivity. I was considering changing to a Yaesu FT 897.....

Richard
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WB2WIK
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« Reply #3 on: November 15, 2005, 07:44:37 AM »

Unless something's wrong with the IC-706, changing receivers isn't likely to "pull in" weak signals any better.

Where the 706 falls apart, and so do most "mobile" rigs, is when trying to receive weak signals amongst very strong signals.  If you have a small, compromise loop antenna you may not have this problem (being bombarded with very strong signals), and if not, there's nothing to fix with the receiver.

The way to make signals stronger is to use bigger antennas, especially considering where we are in the sunspot cycle....

73,

Steve WB2WIK/6
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K7VO
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« Reply #4 on: November 15, 2005, 12:28:33 PM »

I'm going to disagree with Steve, WB2WIK/6, which I rarely do.  I had the original IC-706 not long after they first came out.  The low audio on transmit was a known problem and there is a mod for it.  The poor receiver performance was not due to any lack of sensitivity (Steve is right about that) but is due to a really high receiver noise floor.  You are correct that your radio is a poor performer.

Good inexpensive second hand rigs that will easily outperform your IC-706:

Icom IC-740
Kenwood TS-830S
NCG 10/160M (a/k/a National RJX-810D)
Ten Tec Corsair, Argosy II, Omni D Series C
Yaesu FT-107M

These all date from the 80s.  Narry a one has a general coverage receiver.  All have reputations as outstanding performers in their day and they still hold their own very well today (as in much better than your original IC-706).  The TS-830S has tubes for the finals and driver which is why I generally would avoid it, but of the last generation of hybrid rigs it was probably the best.  The Yaesu FT-102 has a similarly great reputation but I have never owned one so I can't include it in my list.

There is one radio from the late '70s I'd put in the same class:  the Tempo (Uniden) 2020.  The receiver is superb but... they are complex rigs that have not aged gracefully.  Be prepared to do some repair work if you consider one.  Once again, this is a hybrid design.

I should note that the IC-706 has improved greatly over the years.  The IC-706MkIIG is much better than the original.  That may be the rig Steve is thinking of.

73,
Caity
K7VO
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G4JJP
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« Reply #5 on: November 15, 2005, 03:44:10 PM »

Thanks.

This answers two concerns.  First, it helps me to pin the problem that I was feeling, rather than rationalising, with the 706.  I was fairly sure the rig was a bit deaf, but if the noise is in the receiver, that kind of explains stuff.  Second, I had been struggling with noise, thinking it was all in the antenna system, and trying all sorts of antenna builds to eliminate the high noise base.  

I will go for one of the rigs you suggest as the base rig, but still need some kind of portable / mobile.  What do you think of the Yaesu 897D?

Richard
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K7VO
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« Reply #6 on: November 15, 2005, 04:19:03 PM »

I've played extensively with the FT-857D.  My understanding from all I've been told is that the receiver in the 897 and 857 is essentially the same.

If that is so.... it's still doesn't have the quietest receiver in the world, but it's head and shoulders over the original IC-706. (Note I said original, not current version, which is much better.) Please realize that all DC-to-daylight rigs compromise on performance to get it all in one box.  Most hams understand and accept this trade off.  If you don't want to accept it you end up with separate HF and VHF rigs, much like Ten Tec's Argonaut V and 6N2.  That's a far less popular approach but those two rigs have very fine (and very quiet) receivers.

The menu system in the 857, 897, and 817 is quite different from Icom's.  I find the Yaesu system makes more sense to me but I seem to be in the minority on that.

The FT-897D isn't a small rig.  How portable are we talking about?  Picnic table portable or hiking and backpacking portable?

73,
Caity
K7VO
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WB2WIK
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« Reply #7 on: November 15, 2005, 04:20:58 PM »

I never had an "original issue" IC-706, but I did have a MarkII a few years ago.  It had just fine sensitivity, but collapsed when I connected big antennas to it, making it nearly unusable at my home station (but fine for the car).

What happened with the MkII was this:

1.  Everything fine, no noise level with antenna disconnected.
2.  Plug in big antenna (like 20m beam, on 20m), and wall-to-wall signals appeared like the band was open to everywhere at once, and everything was S9+.
3.  Tune around, find most of those signals aren't even there, they're just spurious responses created by the receiver due to overload.
4.  Add external 20 dB attenuator, most of the "crap" disappeared, but then of course so did 20 dB worth of signals I was trying to hear, so this isn't a great permanent solution.

All this is with "preamp OFF."

I tried this again with my friend's (WA6NCN's) borrowed MkIIG and had pretty much the same results.

So, it wasn't "sensitivity," which measured as good as anything I own on the bench, using a signal generator; it was just poor immunity to overload from strong signals both within and outside the bands.

Unless I drove past a broadcast station or something, I'd never notice this in the car.

The rigs that do *not* "tune" outside the ham bands usually are better, and I agree with Caity's list.  I'd add a few more of my own, but it's not important.

I don't remember the crappy transmit audio.  Maybe mine didn't have that problem, or if it did, I don't remember hearing about it.

WB2WIK/6
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K7VO
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« Reply #8 on: November 15, 2005, 08:24:53 PM »

For WB2WIK/6, Steve:

Your Mark II, for all it's faults, was head and shoulders above the original version.  It was almost a decent radio Smiley  It certainly didn't have as much internally generated receiver noise as the original.

In addition to the front-end overload you report, the original also suffered horribly from intermod on 2m and 6m and was unusable on 2m SSB/CW.  

The transmit audio problem was unique to the original.  Icom had a service bulletin on that one so I am sure the fix was incorporated into your Mark II.

I'm not a big fan of any generation of the IC-706 for the very reason you cite.

Feel free to add to my list.  I usually learn something when you contribute Smiley

73,
Caity
K7VO
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G4JJP
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« Reply #9 on: November 16, 2005, 01:37:53 AM »

How portable are we talking?

Well, my main interest is offshore yachting, but I don't like the economics of owning a boat, so tend either to sail with friends, or charter.  The idea is to own a rig that can double as a base station at home most of the time, but can be taken on board and set up easily when I sail. So it would have to be fairly portable, which would rule out a larger older base station rig.

Hence the Icom 706, as a lot of Yachts install them permanently because of their small size.  But, as this thread shows, I have problems with the ears of my Mk 1 Icom 706, as well as its SSB output.  So, my second thought was to go for a second, older, base station rig (and the Icom IC 740 is my first choice from the ones you list).

But then, reading the reviews of the Yaesu 897D, I thought that if I were to sell my Icom 706, and use that money together with the money I would have to spend on the IC 740, I might just have enough for the Yaesu 897D....  provided the receiver is quiet and sensitive enough to get the Yacht signals I want to listen to.  (I like to listen to 14.303, which is the UK Maritime Mobile net, and would love to be able to pick up the 14.300 net.)

It should be small enough to stow, or to sit on the Chart Table in harbour or at anchor, as installation is not an option on a charter or friend's yacht.

I can get a new Yaesu 897D from Germany for about £530 inc tax and carriage to the UK..... (www.mega-korp.de).

So maybe this tread title needs changing - apologies, but your comments are helping me to think this one through....

Richard
G4JJP

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WB2WIK
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« Reply #10 on: November 16, 2005, 08:40:47 AM »

I think the FT-897 is probably a step up from what you have.  It's surely more modern, and has some additional features including the 60m "channelized" band (which the IC-706 didn't cover), which I understand is a great maritime band with worldwide propagation for seagoing vessels (although I've never used it for that).

The IC-740 was a very slick rig, and I owned two of them back in the early 80's.  But keyword is "early 80's."  I'm not sure I'd buy one today, especially if I had to really rely on it working at sea.  Just too old and too subject to likely failure.

WB2WIK/6
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VE3IOS
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« Reply #11 on: November 16, 2005, 11:03:49 AM »

An Icom 751A would do the trick. Great receiver.
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K7VO
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« Reply #12 on: November 16, 2005, 12:14:25 PM »

The IC-740, IC-751A, and indeed most of the rigs I mentioned are *large* for carrying on board a yacht.  If I knew this was the specification I would have made different suggestions entirely, and yes, they would be "shack-in-a-box" rigs:

Yaesu FT-857D
Icom IC-706MkIIG

The latter is much, much improved over the original.  If you really only care about HF and want top flight receiver performance:

Elecraft K2
Ten Tec Argonaut V

Note these are all current.  The Yaesu, Icom, and Ten Tec are all under $1,000, with the Ten Tec being the least expensive at $849 with no filters to add.

On a boat I'd want general coverage and I'd definitely want reliability so I think I'd stick with current stuff.

Just my .02...

73,
Caity
K7VO
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G4JJP
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« Reply #13 on: November 16, 2005, 01:31:08 PM »

Caity, thanks...

Its more a case that the specification is changing as we discuss this.  Originally, I had thought of getting a base station with good ears, and keeping the Icom 706 for sailing.  Hence the original question.  But in light of this discussion it seems that my Mk 1 706 also needs changing.  Hence the revised spec.

So my original idea of one rig that will serve both base station and sailing needs is sound - just that my choice needs revising....

Richard

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AA4PB
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« Reply #14 on: November 17, 2005, 08:20:38 AM »

It seems to me that telling if the noise is generated in the receiver or coming from the antenna is fairly easy to determine. If the noise level drops significantly when you disconnect the antenna then its coming in the antenna and getting a receiver with a lower noise floor won't provide much benefit. I suspect that much of it depends on what band we are talking about. On 10M a lower noise receiver may help a great deal. On 75M the receiver noise is probably swamped by band noise picked up by the antenna.
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