Date   
Re: Dealing With AM Broadcast Band Interference

luuk_h <luuk_h@...>
 

Yes, strange things do happen. I had a similar problem.

I am not sure you have the same problem. Here is my story just to
illustrate that you can expect the unexpected.

I build mine for LSB and USB using 2 separate 9 Mhz xtal oscillators.
It had a lot of BC breakthrough using USB but none at all when using
LSB. It turned out that the (unshielded) coil of the 9MHZ xtal
oscillator picked it up. After rotating it 90 degrees the problem was
solved. Now I have shielded the whole thing.


good luck.



--- In BITX20@..., farhan@... wrote:



nader,

i suppose by AM broadcast you don't mean the short-wave AM inside
the ham
bands but the medium wave AM that transmits in the 600khz-1600khz band.

the bitx has a crystal filter in its signal path, which means that
there
is no way for AM to get through via the signal path. It is evidentally
getting through some other route.

As usual, the way to fix this by following the advice of julius caeser:
divide and conquer. start from the audio stage and work your way
back to
the antenna.

1) does the volume control accordingly cut down the am interference
too?
If no, then the AM is getting picked up by the LM 386, look for bypass
problems. Are pins 2 and 3 properly soldered? is the bypass cap
soldered
upside down? etc...

2) am interference is coming further up the signal chain ...
cut off the power to the IF and RF amps. are you still getting the
AM? No?
Which stage is picking it up? You can also try disconnecting one stage
from the other to see where the AM is coming from.


3) does AM come up only when you plug in the antenna? what about
using a
battery instead of a DC power supply? AM can sneak through leaky power
cables as well as grounding of the entire circuit.

4) are you using very long wires between stages and are these not
shielded? (audio cables can be used for short runs).

the key thing to udnerstand is that this is not a 'usual' problem with
bitx which means, it is not encountered by many. hence, it is most
probably a result of a soldering mistake. at time, one tends to
develop a
blind eye to the obvious mistake in the wiring. if you have someone
else
who can read a circuit, have them validate your build against the
circuit
diagram.

dont spend too much time banging at the thing, take a break, have a
drink
and then come back to the workbench. there is an obvious mistake
somewhere. as my doc keeps saying that in medicine, they don't go
looking
for the zebra, they look for the horse. almost always, the wierdest
problems have the simplest causes.

- farhan


On Sat, 29 Sep 2007, st2nh wrote:

Hi all
I have fixed my homebrew BITX 20 , on checking the receiver I
suffered
a lot from AM broadcast interference. I use a different setup for the
front-end but all were fail to stop interference. I'm thinking of a
wave trap!
Any clue or ideas?
Thank -73
Nader &#65533; st2nh


[Non-text portions of this message have been removed]

Hendricks QRP Kits BitX20A Shipping List Kits 51 - 100

KI6DS <ki6ds@...>
 

Here is the list of Kits shipped this morning.

David Craggs
James Newland
John Horton
Arnold Grubbs
David Ek
Torbjorn D Kallner
Warren David McRobie
Tucker Gary
Jeffrey Jaquays
John M. Foster
John Burton
Ulrich Henzler
R Dominic A Baines
Robert O'Bannon, 2 Kits
James Southwick
Klaus Rosenplaenter, DK6AO
Floyd Loftis
Baino Paul
Joel Myers
Marco Cortesi
David Delakas
David Millican
David Kelley
Antonio Pacheco
Paul McKee
Walter Salden
Lou Scottoline
Cubed Electronix, Inc.
Oliva Enrico
Luis Terres Salto
David Glyn Evans
Peter Norman
James Southwick
Ronald van den Brink
Ronald Hambric
Alan Biocca
David Millington
Alan Johns
Jeho Lee
Michael Audette
Thomas Coelho
Morris Jones
Michael Innes
Gregory Beat
Greg Derda
Mark Campbell
gurcan topukcu
Centro Sviluppo Sistemi srl
Michael C Taylor

72, Doug, KI6DS

Re: Hendricks QRP Kits BitX20A Shipping List Kits 51 - 100

Martin Peters <martin.peters@...>
 

Hi - anyone in Britain received theirs from the FIRST batch yet? I read
various acknowledgements of delivery in Europe but nothing arrived here so
far.



Regards to all - Martin, G4EFE

Re: Hendricks QRP Kits BitX20A Shipping List Kits 51 - 100

Lee Mairs (SAG) <lmairs@...>
 

Heck! My lot #1 order hasn't even gotten to West (By God) Virginia yet!
73 de Lee
KM4YY/8



Martin Peters wrote:


Hi - anyone in Britain received theirs from the FIRST batch yet? I read
various acknowledgements of delivery in Europe but nothing arrived here so
far.

Regards to all - Martin, G4EFE


BITX20A and C92

n7ve <dan.Tayloe@...>
 

At the last moment, I added a change to the BITX20A to add more margin
to reducing the second harmonic. I added C92, a 68pf capacitor, to
the transmit low pass filter to reduce the second harmonic to be
roughly 55 db down.

Jim's BIT20A had second harmonics that were 60 db down without this
cap (43 db down is the FCC limit). The advantage of running push-pull
is that the second harmonic tends to be greatly reduced. However, my
unit was more marginal than his, thus this change seemed to be a good
idea.

Unfortunately, C92 (68 pf) did not get included in the bill of
material that I sent Doug for the kits. The second harmonic should be
ok without the cap, but would be much improved with it.

However, L1 should be 12T with C92, and 14T without C92.

- Dan, N7VE

Re: Experimental bi-directional SSB exciter

Rahul Srivastava
 

Hi! Steve,

I am a great fan of your simple designs. I am willing to take a shot
at this new TRX. I wish to make a single sided board as it is easy
to manufacture. Linear et all I am still drooling over fine design
of the output stage of Hendrick kits BITX stage.

Regarding your comments on slightly low AF O/P I feel I should add
an active decoupled common base AF preamp before LM386. I hope you
wont mind my palgarisation.

73

Rahul VU3WJM




--- In BITX20@..., Steven Weber <kd1jv@...> wrote:

I built a bi-directional SSB exciter using a complementry PNP/NPN
amplifier
design I found in EMIRFD and 74HC4053 analog switches as the
mixers. It
works remarkably well. If you'd like to take a look, schematic and
discription can be found at <http://kd1jv.qrpradio.com/bi_ssb/bi-
ssb.HTM>


72,
Steve, KD1JV
"Melt Solder"
White Mountains of New Hampshire
http://kd1jv.qrpradio.com

Re: Experimental board for KD1JV IC version of BITX

ve7hcw <cw_keyer@...>
 

Hi Vaclav

sorry that I didn't post his schematic but I just uploaded a PDF
copy of his web HTML in the "PCB for KD1JV IC BITX" file . added also
revised PCB version 1.02 with the gain capacitor added for pin 1 and pin8
of the LM386 amplifier.Mention inside this document is how to do toner
method PCB boards without tears and frustrations.The web site for this
method is http://www.fullnet.com/~tomg/gooteepc.htm . Tom Gootee will
explain it nicely on his site.

wayne ve7hcw

SNIPPED

--- In BITX20@..., "medvidec" <vaclavpe@...> wrote:

Hello all,

what do you mean by "IC BITX" ? Is it the bidirectional ssb excite
that Steve recently posted here ?

Maybe I am blind but I can't find a link from Steve's home page.

Thank you,
Vaclav

--- In BITX20@..., "ve7hcw" <cw_keyer@> wrote:

Hi Steve

your right on ,the first mixer is correct but the BFO is
transposed . I have corrected the BFO mixer on the BFO module pcb and
the laser tone PCB and the jumper JPEG diagram and reposted under the
files.
wayne ve7hcw

------------------------------------------------------
Snipped

BITX20 microphone?

Greg Derda
 

Hi All,

I haven't seen this discussed in the assembly doc, nor can I find much in the list archives, so I'll go ahead and ask: What kind of microphone(s) can be used with the BITX20? I am hoping that my little Ten_Tec 701 "electret" will work, but I am curious about other options as well.

Thanks in advance,
Greg (of the Group 2 Hendrick's kit mailing)
ki4mmm

Mistakes on BITX-20A layout diagram

Steven Weber <kd1jv@...>
 

I finally printed out the layout diagram and and schematic for the
Hendricks BITX20A today and noticed a couple of mistakes.

Q26 should be 2N7000, not 3904
Q21 should be FQN1N50C, not 2N7000

R17 is 10 ohms, couldn't find it on the schematic when I labled the diagram
1 ufd caps are 10 ufd caps.

I was hoping I'd get my kit today, but still no show in NH. Going on a 3
day hiking trip tomorrow to catch the fall colors, so maybe it will be here
when I get back Friday.

72,
Steve, KD1JV
"Melt Solder"
White Mountains of New Hampshire
http://kd1jv.qrpradio.com

Re: Experimental board for KD1JV IC version of BITX

Steven Weber <kd1jv@...>
 

"" ? Is it the bidirectional ssb exciter
that Steve recently posted here ?

Maybe I am blind but I can't find a link from Steve's home page.
I haven't added a link on my projects page for that circuit yet. This is
the direct link <http://kd1jv.qrpradio.com/BI-SSB/bi-ssb.HTM>

I redid my web site using MS Publisher recently and that was a mistake, as
its now a pain in the butt to do updates. I need to go back to my simpler
web page designer.


72,
Steve, KD1JV
"Melt Solder"
White Mountains of New Hampshire
http://kd1jv.qrpradio.com

Re: BITX20 microphone?

Charlie <charlie@...>
 

--- In BITX20@..., Greg Derda <gderda@...> wrote:

Hi All,

I haven't seen this discussed in the assembly doc, nor can I find much
in the list archives, so I'll go ahead and ask: What kind of
microphone(s) can be used with the BITX20? I am hoping that my little
Ten_Tec 701 "electret" will work, but I am curious about other options
as well.

Thanks in advance,
Greg (of the Group 2 Hendrick's kit mailing)
ki4mmm
I was planning to use the mic from my ICOM IC 703 (HM 103) assuming
that I can find a panel mounting 8 pin modular sockeT!


Charlie.
M0WYM

C92?? for Hendricks QRP Kits, What will happen??

KI6DS <ki6ds@...>
 

Guys, as Dan has already posted, C92 was not in the first 100 kits
shipped. Since it is really not needed to meet FCC specs, but was
added later for "margin", I will not be shipping a cap to those of you
who were in the first 100. I will however, be adding the cap to the
kits from 101 on. It is not a matter of cost, but of the time required
to do so (ship the cap to the first 100), and as it is not really
required, I am asking your indulgence on this. 72, Doug, KI6DS

Re: Experimental board for KD1JV IC version of BITX

Jim Tonne <tonne@...>
 

I need to go back to my simpler web page designer.
I use WordPad!
http://tonnesoftware.com/

- JimT

Re: Hendricks QRP Kits BitX20A Shipping List Kits 51 - 100

Paul Brice-Stevens <paul@...>
 

Hi Martin,

Got my two

73 Paul g0wAT

Martin Peters wrote:


Hi - anyone in Britain received theirs from the FIRST batch yet? I read
various acknowledgements of delivery in Europe but nothing arrived here so
far.

Regards to all - Martin, G4EFE



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Re: Experimental bi-directional SSB exciter

Steven Weber <kd1jv@...>
 

Regarding your comments on slightly low AF O/P I feel I should add
an active decoupled common base AF preamp before LM386.
That would likely be a good idea.

I hope you wont mind my palgarisation.
Not at all, that was the whole point of making the circuit public. I'm just
glad some people are interested in it and are going to the trouble of
designing boards and making improvments to it.

72,
Steve, KD1JV
"Melt Solder"
White Mountains of New Hampshire
http://kd1jv.qrpradio.com

Re: C92?? for Hendricks QRP Kits, What will happen??

Lee Mairs (SAG) <lmairs@...>
 

What!! You mean you screwed me out of a capacitor???

No problem, Doug. We shouldn't have too much problem finding one if we really want to put in the effort. The last time you sent me a missing part I felt guilty as it cost you way more in shipping than the part itself cost.

73 and thanks for all your efforts to help out fellow hams,
Lee
KM4YY/8



KI6DS wrote:


Guys, as Dan has already posted, C92 was not in the first 100 kits
shipped. Since it is really not needed to meet FCC specs, but was
added later for "margin", I will not be shipping a cap to those of you
who were in the first 100. I will however, be adding the cap to the
kits from 101 on. It is not a matter of cost, but of the time required
to do so (ship the cap to the first 100), and as it is not really
required, I am asking your indulgence on this. 72, Doug, KI6DS

Re: BITX20 microphone?

Arv Evans
 

Greg & others

The original BITX20 used an electret type mike, the type with an
internal J-FET amplifier. In the BITX20A kit Dan allowed for using
either an amplified mike like the Electret or a non-amplified unit. If
using an amplified mike you will need to include resistor R-92, (4.7K).
If not using an electret microphone then do not install this resistor.

Arv
_._


Greg Derda wrote:


Hi All,

I haven't seen this discussed in the assembly doc, nor can I find much
in the list archives, so I'll go ahead and ask: What kind of
microphone(s) can be used with the BITX20? I am hoping that my little
Ten_Tec 701 "electret" will work, but I am curious about other options
as well.

Thanks in advance,
Greg (of the Group 2 Hendrick's kit mailing)
ki4mmm

Re: Hendricks QRP Kits BitX20A Shipping List Kits 51 - 100

Lee Mairs (SAG) <lmairs@...>
 

I'd love to hear to USPS explanation as to why kits get over seas before they get to WBGV.

My box was empty this afternoon again...
73 de Lee
KM4YY/8



Paul Brice-Stevens wrote:


Hi Martin,

Got my two

73 Paul g0wAT

Martin Peters wrote:

Hi - anyone in Britain received theirs from the FIRST batch yet? I read
various acknowledgements of delivery in Europe but nothing arrived
here so
far.

Regards to all - Martin, G4EFE




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Re: Hendricks QRP Kits BitX20A Shipping List Kits 51 - 100

Ronald Scifleet <ronaldscifleet@...>
 

Hi All,

I've received my Bitx20A kit the the mail today. It took a week from US to Australia.

73 Ron VK2YQJ

----- Original Message ----
From: Paul Brice-Stevens <paul@...>
To: BITX20@...
Sent: Tuesday, 2 October, 2007 7:28:52 AM
Subject: Re: [BITX20] Hendricks QRP Kits BitX20A Shipping List Kits 51 - 100

Hi Martin,

Got my two

73 Paul g0wAT

Martin Peters wrote:

Hi - anyone in Britain received theirs from the FIRST batch yet? I read
various acknowledgements of delivery in Europe but nothing arrived here so
far.

Regards to all - Martin, G4EFE





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http://www.eset. com



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Re: Hendricks QRP Kits BitX20A Shipping List Kits 51 - 100

Arv Evans
 

They get more money for overseas delivery...?
_._

Lee Mairs (SAG) wrote:


I'd love to hear to USPS explanation as to why kits get over seas before
they get to WBGV.

My box was empty this afternoon again...
73 de Lee
KM4YY/8

Paul Brice-Stevens wrote:

Hi Martin,

Got my two

73 Paul g0wAT

Martin Peters wrote:

Hi - anyone in Britain received theirs from the FIRST batch yet? I
read
various acknowledgements of delivery in Europe but nothing arrived
here so
far.

Regards to all - Martin, G4EFE





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