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KXB3080 problem

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Soaring Eagles

KXB3080 problem

Hi Folks!

I build KX1 sn/1519 and it worked great! I finished building up the KXB3080
and installed it last night. All the tests were fine as I went along in the
build. However, when I try to peak the receiver, I'm not getting any
signals. I don't have an XG1 or 2, although I might need one! <grin> Also,
it doesn't make any difference where I set the RF Gain control, and I'm
thinking that's significant. I've looked for the obvious shorts and
incorrectly installed parts but can't find any.

I'd appreciate any help. I usually get just the digest, so if you want to
respond direct, please do so.

Thanks a lot!!!

Jim Ujcik, WD9HBC
[hidden email]

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David Toepfer

Re: KXB3080 problem

I had a similar problem (not no signals, just no pronounced peak) when I was
trying to use an antenna through a balun. When I removed the balun the issue
was resolved. The peaks were much more pronounced.

David, k3tue
.

--- Soaring Eagles <[hidden email]> wrote:

> Hi Folks!
>
> I build KX1 sn/1519 and it worked great! I finished building up the KXB3080
> and installed it last night. All the tests were fine as I went along in the
> build. However, when I try to peak the receiver, I'm not getting any
> signals. I don't have an XG1 or 2, although I might need one! <grin> Also,
> it doesn't make any difference where I set the RF Gain control, and I'm
> thinking that's significant. I've looked for the obvious shorts and
> incorrectly installed parts but can't find any.
>
> I'd appreciate any help. I usually get just the digest, so if you want to
> respond direct, please do so.
>
> Thanks a lot!!!
>
> Jim Ujcik, WD9HBC
> [hidden email]
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
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> Elecraft web page: http://www.elecraft.com
>

Don Wilhelm-3

RE: KXB3080 problem

In reply to this post by Soaring Eagles

Jim,

One thing that will cause that problem is if the 'D' and '5' wires are
interchanged - they should cross over each other (guess how I discovered
that <G>)

Did you make the PC trace cut on the KX1 board?
Is T2 wound correctly and installed properly? - it should look like the
photos. Were the toroid leads properly stripped? The unstripped lead
length is rather critical in the KXB3080, but the proper lengths are
indicated in the manual.
Did you place the 'A' and 'B' wires as indicated in the manual? - they are
mixed on the KXB3080 board, so the wire marked A on the KXB3080 goes to the
B position on the KX1 board, etc.

Have you checked transmmit yet? If you get proper RF output, you can be
reasonably certain that the Low Pass Filter is OK, but if you find no or low
power on transmit, look at the Low Pass Filter for the problem. The LPF
(and the DDS) are the only components shared by both the receiver and the
transmitter.

73,
Don W3FPR

> -----Original Message-----
>
> I build KX1 sn/1519 and it worked great! I finished building up
> the KXB3080
> and installed it last night. All the tests were fine as I went
> along in the
> build. However, when I try to peak the receiver, I'm not getting any
> signals. I don't have an XG1 or 2, although I might need one!
> <grin> Also,
> it doesn't make any difference where I set the RF Gain control, and I'm
> thinking that's significant. I've looked for the obvious shorts and
> incorrectly installed parts but can't find any.
>

Craig Rairdin

RE: KXB3080 problem

Building the KXB3080 is like that old game where the teacher gives everyone
a piece of paper where the first instruction was "Read all instructions
before doing anything". There'd be all kinds of instructions like "stand up
and sing the national anthem" and "yell out the name of the person next to
you". Then the last instruction was "Don't do any of the instructions above.
Write your name on the top of the paper and hand it back to the instructor."
The whole thing was an exercise in following instructions.

With its mislabelled pads, cut traces, wires that cross each other, torroids
that are mirror images of each other but with exact yet different
strip-lengths, the KXB3080 is probably the most challenging Elecraft kit to
get right. Not to mention the gymnastics required to install it without
shorting that one wire that has to cross behind the board without shorting
to the pad right next to it. And making it fit under the ATU.

I love it. :-)

Craig
NZ0R

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Wilhelm
Sent: Wednesday, August 16, 2006 4:00 PM
To: Soaring Eagles; [hidden email]
Subject: RE: [Elecraft] KXB3080 problem

Jim,

One thing that will cause that problem is if the 'D' and '5' wires are
interchanged - they should cross over each other (guess how I discovered
that <G>)

Did you make the PC trace cut on the KX1 board?
Is T2 wound correctly and installed properly? - it should look like the
photos. Were the toroid leads properly stripped? The unstripped lead
length is rather critical in the KXB3080, but the proper lengths are
indicated in the manual.
Did you place the 'A' and 'B' wires as indicated in the manual? - they are
mixed on the KXB3080 board, so the wire marked A on the KXB3080 goes to the
B position on the KX1 board, etc.

Have you checked transmmit yet? If you get proper RF output, you can be
reasonably certain that the Low Pass Filter is OK, but if you find no or low
power on transmit, look at the Low Pass Filter for the problem. The LPF
(and the DDS) are the only components shared by both the receiver and the
transmitter.

73,
Don W3FPR

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David Toepfer

RE: KXB3080 problem

--- Craig Rairdin <[hidden email]> wrote:
> the KXB3080 is probably the most challenging Elecraft kit to get right.

I agree.

> Not to mention the gymnastics required to install it without
> shorting that one wire that has to cross behind the board without shorting
> to the pad right next to it.

I decided before i even got to that part that that would need insulation.

> And making it fit under the ATU.

That was the tricky part for me. I thought I had it all together and then when
I tried to put the ATU on I had to unsolder the LPF module and reposition it.

David, k3tue
.

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Soaring Eagles

RE: KXB3080 problem

In reply to this post by Don Wilhelm-3

OK, I really appreciate your quick response!

I forgot to mention that the 20B cap does have a peak (not too much, but
about the same as before, but there's no peak on 20A or 40. Also can't hear
a peak on 30A or 30B.

'D' and '5" are correct
The trace is cut (I thought I might not have done it, so I did it again. ;)
But, if I check do a continuity check on both sides of the old trace, I get
a short. I have not taken the time to check this against the schematic, but
I did check it.

T2 is wound correctly and installed properly and it does look like the
photos. I followed the directions for stripping the toroids, so I'm not
sure exactly what you mean here. What unstripped lead length would be a bad
thing? If you're thinking that one of the leads is shorting somewhere it
shouldn't, it doesn't appear to visually.

Yes, the 'A' and 'B' wires are correct (quadruple checked).

I did check transmit into a dummy load and here's what I get on my OHR WM-2
80 meters: 2 watts
40 meters: 3.5 watts
30 meters: 5.0 watts
20 meters: 3.2 watts

battery voltage shows 14.1 volts

Interestingly, the same setup showed 5 watts out on both 40 and 20 prior to
the KXB3080 installation.

And, as I was typing this, I decided to hook back up the antenna and see
what I heard. Well, signals were booming in on 80. Went to each band in
turn and was able to successfully peak the 40, 30, and 20 meter filters.

So, what did I do? Don't really know. Other than going over everything
about 10 times (no kidding) and scraping gently at 2 solder points that may
(emphasize may) have been shorting. They didn't really look like they were,
but there was some flux and it was shiny in the light, so I scraped a
little between them. Don't even remember which ones they were. But, they
were in the L6 and R1 part of the KX1 board and prolly one of the
resoldered parts or very close to one.

I'll complete the reassembly. I planned on taking this on a trip to TX this
week and was sweating not having it done in time. Hopefully I won't undo
what I did do.

Thanks to everyone for putting up with the bandwidth!

Many thanks and 72 to Don. At least having some plan of action kept me
going when I might have just given up til I got back from my trip!

Jim, WD9HBC

At 05:00 PM 8/16/2006, Don Wilhelm wrote:

>Jim,
>
>One thing that will cause that problem is if the 'D' and '5' wires are
>interchanged - they should cross over each other (guess how I discovered
>that <G>)
>
>Did you make the PC trace cut on the KX1 board?
>Is T2 wound correctly and installed properly? - it should look like the
>photos. Were the toroid leads properly stripped? The unstripped lead
>length is rather critical in the KXB3080, but the proper lengths are
>indicated in the manual.
>Did you place the 'A' and 'B' wires as indicated in the manual? - they are
>mixed on the KXB3080 board, so the wire marked A on the KXB3080 goes to the
>B position on the KX1 board, etc.
>
>Have you checked transmmit yet? If you get proper RF output, you can be
>reasonably certain that the Low Pass Filter is OK, but if you find no or low
>power on transmit, look at the Low Pass Filter for the problem. The LPF
>(and the DDS) are the only components shared by both the receiver and the
>transmitter.
>
>73,
>Don W3FPR

Don Wilhelm-3

RE: KXB3080 problem

Jim,

It certainly sounds like you got it fixed even if you don't know why -
congratulations.

You can likely improve the 20 meter output by spreading the green winding on
the LPF inductors a bit, and 80 meters may improve by squeezing the red
turns a bit. 30 meters will normally have more output than the other bands.

Enjoy your trip.

73,
Don W3FPR

> -----Original Message-----
>
> I did check transmit into a dummy load and here's what I get on
> my OHR WM-2
> 80 meters: 2 watts
> 40 meters: 3.5 watts
> 30 meters: 5.0 watts
> 20 meters: 3.2 watts
>
> battery voltage shows 14.1 volts
>
> Interestingly, the same setup showed 5 watts out on both 40 and
> 20 prior to
> the KXB3080 installation.
>
> And, as I was typing this, I decided to hook back up the antenna and see
> what I heard. Well, signals were booming in on 80. Went to each band in
> turn and was able to successfully peak the 40, 30, and 20 meter filters.
>
> So, what did I do? Don't really know. Other than going over everything
> about 10 times (no kidding) and scraping gently at 2 solder
> points that may
> (emphasize may) have been shorting. They didn't really look like
> they were,
> but there was some flux and it was shiny in the light, so I scraped a
> little between them. Don't even remember which ones they were. But, they
> were in the L6 and R1 part of the KX1 board and prolly one of the
> resoldered parts or very close to one.
>
> I'll complete the reassembly. I planned on taking this on a trip
> to TX this
> week and was sweating not having it done in time. Hopefully I won't undo
> what I did do.
>
> Thanks to everyone for putting up with the bandwidth!
>
> Many thanks and 72 to Don. At least having some plan of action kept me
> going when I might have just given up til I got back from my trip!
>
> Jim, WD9HBC
>

Paul Neuman

Re: KXB3080 problem

In reply to this post by Soaring Eagles

I too had David's (k3tue) problem tuning for a peak on 20M and 40M after
completing the base kit. When I tuned the receiver at the end of Part
II, I connected directly to my longwire and was able to easily peak each
band.

For the final tune, I plugged in my longwire via a 4:1 balun. I went
back and fourth too many times trying to peak both bands. Just had a
devil of a time and finally got it the best I could and left it. Had
the feeling that something wasn't right and was afraid I had screwed up
something in the Part III construction.

A couple of days later I took the rig outside to give it a try from the
patio with just a 28 ft wire.
Decided to try tuning it again and both bands peaked right up. Turned
out I had been pretty close.

Decided to get the XG2 to use when I install the 3080. It just came in
the mail so I have a little build to look forward to. I have the 3080
all built, just have to work up the nerve to try installing the thing in
my functioning KX1. Think I'll go back and check the toroids again.

Paul, kd2mx

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