Anyone got their KXB3080?

[J. Coote]

I downloaded the KXB3080 manual and had some questions:

How hard is it to put together for a KX-1 that has already had the KXB30 30M
unit and auto antenna tuner installed?

Has anyone found some universal wire antenna lengths that will work with the
KX-1 and internal antenna tuner - over all four (80, 40, 30, 20) bands?

Thanks,

Jay
W6CJ


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[Ron D'Eau Claire-2]

Jay, W6CJ wrote:

I downloaded the KXB3080 manual and had some questions:

How hard is it to put together for a KX-1 that has already had the KXB30 30M
unit and auto antenna tuner installed?

Has anyone found some universal wire antenna lengths that will work with the
KX-1 and internal antenna tuner - over all four (80, 40, 30, 20) bands?

----------------------------------

As the manual indicates, the first step is to remove the KXB30 module if one
is installed. Then it's the same process as for a KX1 that did not have the
KXB30 module.

The KXAT1 tuner just unplugs, as described in the manual. The manual shows
how to install a simple jumper that routes RF to the antenna jack for
testing until you're done with the upgrade and ready to replace the KXAT1.

There's more to the KXB3080 upgrade than for just the KXB30 because for the
KXB3080 installation the whole receiver input circuit is modified. It's
changed from a simple capacitively-coupled input to a transformer-coupled
input.  What you get for the effort is a receiver with slightly improved
performance on all the bands, not just on 80.

I've seen some posts of people working on combinations of wire lengths for
an 80/40/30/20 meter antenna that the KXAT1 can match easily, but I haven't
followed them closely. I'll leave it to one of those who actually did that
work to answer that question.

Ron AC7AC

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[Don Wilhelm-3]

Jay,

As you no doubt noticed when reading the instructions, the KXB3080 does take
a bit more care and patience than most.  In fact, I would rate it as the
most critical construction item that Elecraft has produced.  It takes care
and careful attention to the instructions if one expects everything to fit
together and work when complete.

After doing 12 of these upgrades, and repairing 3 others, I can easily do
the job in a couple hours now, but the first couple times it took a lot
longer to get it right and refine my technique.  I do recommend Mychael's
pre-wound toroids because they are a bit tricky to wind and tin the leads
properly.  Mychael's price is $9 per set plus $6 for shipping based on the
latest info I have, and I consider it a bargain.

If you need me to do the KXB3080 install for you, I charge $39 plus $10 for
pre-wound toroids (I order in bulk and pass along the savings) and $16 for
return packing and insured shipping - total $65.  I try to turn these around
in a couple days so you are not without your KX1 for a long time.

The only advice I can offer on the antenna is to stay away from lengths that
are 1/2 wavelength on any band for either the radiating element or
counterpoise wires (assuming direct connect to the KX1 with no tuner - or
feedline plus radiator lengths) - the W3EDP lengths of 85 ft and 17 feet
have been found good by several folks, and I can say that my doublet 22 ft
per side with a 25 ft parallel transmission line feedline (47 ft total per
side) works nicely on 80, 40 and 20, although it is getting close to a half
wave on 30 meters where I have to experiment with adding or subtracting a
bit of feedline.

73,
Don W3FPR

> -----Original Message-----
>
> I downloaded the KXB3080 manual and had some questions:
>
> How hard is it to put together for a KX-1 that has already had
> the KXB30 30M
> unit and auto antenna tuner installed?
>
> Has anyone found some universal wire antenna lengths that will
> work with the
> KX-1 and internal antenna tuner - over all four (80, 40, 30, 20) bands?
>
> Thanks,
>
> Jay
> W6CJ
>

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[Alexandra Carter]

Ugh. The 30m module kicked my butt, had to install it 2X plus lots  
and lots of fiddling around with it.
I can't imagine doing the 3080 now. I guess for multi-band the  
easiest was always the NorCal Sierra, plug 'em in and plop! there's  
another band lol. 73 de Alex NS6Y


On Jun 24, 2006, at 10:02 AM, Don Wilhelm wrote:


>
> As you no doubt noticed when reading the instructions, the KXB3080  
> does take
> a bit more care and patience than most.  In fact, I would rate it  
> as the
> most critical construction item that Elecraft has produced.
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[Bob Nielsen]

On Jun 24, 2006, at 10:16 AM, Alexandra Carter wrote:

> Ugh. The 30m module kicked my butt, had to install it 2X plus lots  
> and lots of fiddling around with it.
> I can't imagine doing the 3080 now. I guess for multi-band the  
> easiest was always the NorCal Sierra, plug 'em in and plop! there's  
> another band lol. 73 de Alex NS6Y

Of course the Sierra was designed by a recognized master of the  
craft!  The band plugins remind me of the old National HRO series  
receivers.

I still have an unbuilt 30m board for my KX-1.  I should hurry and  
finish it before these 67-year-old eyes get any worse.

73 - Bob, N7XY


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[Bruce Grubbs]

Jay,
I'm currently using a 58-foot end fed wire with 50-foot counterpoise. The SWR
came out at 1.4 on 80m, 1.8 on 40m, and 1.0 on 30 and 20m. That's the best
I've been able to do with an end-fed wire so far.
72,
Bruce
N7CEE
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[David A. Belsley]

Bruce:
   A 50' counterpoise is not ideal for 80 or 40.  Try additional  
counterpoises of 33' and 66'.  Or try using an artificial ground with  
your 50' cp.

best wishes,

dave belsley, w1euy



On Jun 25, 2006, at 10:50 AM, Bruce Grubbs wrote:

> Jay,
> I'm currently using a 58-foot end fed wire with 50-foot  
> counterpoise. The SWR
> came out at 1.4 on 80m, 1.8 on 40m, and 1.0 on 30 and 20m. That's  
> the best
> I've been able to do with an end-fed wire so far.
> 72,
> Bruce
> N7CEE
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-------------------------------------
david a. belsley
professor of economics

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[Ron D'Eau Claire-2]

Bruce N7CEE wrote:
I'm currently using a 58-foot end fed wire with 50-foot counterpoise. The
SWR
came out at 1.4 on 80m, 1.8 on 40m, and 1.0 on 30 and 20m. That's the best
I've been able to do with an end-fed wire so far.

--------------------------

Nothing wrong with that. Any SWR less than, say, 2:1, is probably FB. An SWR
of 1.5:1 or better is "perfect" for all practical purposes.

The point to remember is that the SWR says nothing about how well the
antenna radiates. It only indicates that the rig is able to deliver RF into
the antenna and ground circuits efficiently.

A 60-foot radiator is a pretty good compromise for the KX1. It'll show a
good radiation resistance on 40/30/20 meters and it'll be a lot better than
most temporary radiators on 80.

When working with electrically short radiators (less than 1/4 wave), a
*poor* "counterpoise" or other RF ground will usually *improve* the SWR
obtained. That's because the radiation resistance of such antennas is quite
low. A 1/4 wave is about 35 ohms, but the value drops very quickly as the
antenna is made shorter. It's not unusual for the resistance to be below 10
ohms or even less than 1 ohm in many cases. Since the ground resistance is
in series with the antenna, having a poor, high-resistance ground brings the
value up to help the ATU find a match with a low SWR. That's the good news.
The bad news is that with a fairly high ground resistance, most of the RF is
consumed in making heat in the ground circuit instead of being turned into
electromagnetic waves by the radiator.

What you've accomplished is to have a decent radiator length that improves
the efficiency AND you've accomplished a low SWR for efficient power
transfer from the rig to the antenna.  

Ron AC7AC

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[Bruce Grubbs]

Hi Ron,
I agree... and I don't really care about the radiation pattern because my goal
is a super simple antenna that requires only one support, and that I'm
willing to put up after a long, hard day of backpacking- or quickly for a
lunch break on a day hike or paddle.

72,
Bruce
N7CEE
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[Ron D'Eau Claire-2]

Ha, ha!

You are absolutely right: if the antenna is too much work to put up, you
aren't going to make *any* contacts, not matter how good it might be on
paper...

Ron AC7AC


-----Original Message-----
From: Bruce Grubbs [mailto:[hidden email]]
Sent: Sunday, June 25, 2006 7:26 PM
To: [hidden email]
Cc: Ron D'Eau Claire
Subject: Re: [Elecraft] Anyone got their KXB3080?


Hi Ron,
I agree... and I don't really care about the radiation pattern because my
goal
is a super simple antenna that requires only one support, and that I'm
willing to put up after a long, hard day of backpacking- or quickly for a
lunch break on a day hike or paddle.

72,
Bruce
N7CEE

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