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Guys
I am building a BITX and have the rx working very nice.
However, there is a problem of microphics around the detector/af amp.
Ceramics replaced, as per past postings. No change.
I have now traced this to the balun core and find I have a 'short' of
about 60k between one of the windings and the core.
I have tried different wire and smoothing the holes before winding but
every time I get a 'short'.
I have tried a toroid core and that works without the problem.
Interested to know if anyone else has experienced this and if they
found a fix!
73, Steve, G0FUW

the problem with balun is that it has a sharp edges. these edges nick the enamelled wire being passed around. and the wire gets scrapped and touches the core. if more than two wires get nicked, they short, showing high resistance like you said.

you need to be careful in not pulling the wire too tighly around the edges of the balun. a better way might be to coat the corners with a bit of paint.

- farhan

a bit of insulation tape on the core will certainly help matters.....
\

mm ali
vu2ali



Quoting Ashhar Farhan <farhan@...>:

Chamfering the edges with a bit of emery or sand paper will also work.

73 Raj

--
Raj, vu2zap
Bangalore, South India.

???????? Chamfering the edges with a bit of emery or sand paper will also work.

73 Raj

At 08/07/05, you wrote:
>a bit of insulation tape on the core will certainly help matters.....
>\
>
>mm ali
>vu2ali
>
>
>
>Quoting Ashhar Farhan :
>
> >
> >
> >
> >
> >
> >
> > the problem with balun is that it has a sharp edges. these edges nick the
> >
> > enamelled wire being passed around. and the wire gets scrapped and touches
> >
> > the core. if more than two wires get nicked, they short, showing high
> >
> > resistance like you said.
> >
> >
> >
> > you need to be careful in not pulling the wire too tighly around the
> >
> > edges of the balun. a better way might be to coat the corners with a bit
> >
> > of paint.
> >
> >
> >
> > - farhan
> >
> >
> >
> > On Thu, 7 Jul 2005, g0fuw wrote:
> >
> >
> >
> > > Guys
> >
> > > I am building a BITX and have the rx working very nice.
> >
> > > However, there is a problem of microphics around the detector/af amp.
> >
> > > Ceramics replaced, as per past postings. No change.
> >
> > > I have now traced this to the balun core and find I have a 'short' of
> >
> > > about 60k between one of the windings and the core.
> >
> > > I have tried different wire and smoothing the holes before winding but
> >
> > > every time I get a 'short'.
> >
> > > I have tried a toroid core and that works without the problem.
> >
> > > Interested to know if anyone else has experienced this and if they
> >
> > > found a fix!
> >
> > > 73, Steve, G0FUW
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> > > Yahoo! Groups Links
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >?? YAHOO! GROUPS LINKS
> >
> >
> >
> >
> >??? Visit your group "BITX20" on the web.
> >
> >??? To unsubscribe from this group, send an email to:
> >? BITX20-unsubscribe@...
> >
> >??? Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>

--
Raj, vu2zap
Bangalore, South India.

---

NEW - crystal clear PC to PC

Ashhar and freinds
I have solved my balun core problem. As you guessed, it was caused by sharpe
edges inside the core. I small file and emery paper removed them and
windings now well isolated from core.
For UK builders, Robin at Sycom (sycomcomp.co.uk) stocks the cores - part
number FX2754 about 50p each, I think.
Now, on with the Tx.
73, Steve, G0FUW

Ashhar and freinds
I have solved my balun core problem. As you guessed, it was caused by sharpe
edges inside the core. I small file and emery paper removed them and
windings now well isolated from core.
For UK builders, Robin at Sycom (sycomcomp.co.uk) stocks the cores - part
number FX2754 about 50p each, I think.
Now, on with the Tx.
73, Steve, G0FUW
----- Original Message -----
From: "Ashhar Farhan"
To:
Sent: Friday, July 08, 2005 6:14 AM
Subject: Re: [BITX20] BALUN Core Winding


>
> the problem with balun is that it has a sharp edges. these edges nick the
> enamelled wire being passed around. and the wire gets scrapped and touches
> the core. if more than two wires get nicked, they short, showing high
> resistance like you said.
>
> you need to be careful in not pulling the wire too tighly around the
> edges of the balun. a better way might be to coat the corners with a bit
> of paint.
>
> - farhan
>
> On Thu, 7 Jul 2005, g0fuw wrote:
>
> > Guys
> > I am building a BITX and have the rx working very nice.
> > However, there is a problem of microphics around the detector/af amp.
> > Ceramics replaced, as per past postings. No change.
> > I have now traced this to the balun core and find I have a 'short' of
> > about 60k between one of the windings and the core.
> > I have tried different wire and smoothing the holes before winding but
> > every time I get a 'short'.
> > I have tried a toroid core and that works without the problem.
> > Interested to know if anyone else has experienced this and if they
> > found a fix!
> > 73, Steve, G0FUW
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

---

NEW - crystal clear PC to PC

I have found that a one or possibly two coats of nail polish
(sometimes called nail varnish) of the clear color works well.


Allison
KB1GMX


--- In BITX20@..., Rahul Srivastava <vu3wjm@y...> wrote:

Hi!

To be safe, a layer of plumbers PTFE tape on balun before winding

the coils is helpful.

73

Rahul VU3WJM



Steve Hartley <g0fuw@t...> wrote:
Ashhar and freinds
I have solved my balun core problem. As you guessed, it was caused

by sharpe

edges inside the core. I small file and emery paper removed them and
windings now well isolated from core.
For UK builders, Robin at Sycom (sycomcomp.co.uk) stocks the cores -

part

number FX2754 about 50p each, I think.
Now, on with the Tx.
73, Steve, G0FUW
----- Original Message -----
From: "Ashhar Farhan" <farhan@p...>
To: <BITX20@...>
Sent: Friday, July 08, 2005 6:14 AM
Subject: Re: [BITX20] BALUN Core Winding

the problem with balun is that it has a sharp edges. these edges

nick the

enamelled wire being passed around. and the wire gets scrapped and

touches

the core. if more than two wires get nicked, they short, showing high
resistance like you said.

you need to be careful in not pulling the wire too tighly around the
edges of the balun. a better way might be to coat the corners with

a bit

of paint.

- farhan

On Thu, 7 Jul 2005, g0fuw wrote:

Guys
I am building a BITX and have the rx working very nice.
However, there is a problem of microphics around the detector/af

amp.

Ceramics replaced, as per past postings. No change.
I have now traced this to the balun core and find I have a

'short' of

about 60k between one of the windings and the core.
I have tried different wire and smoothing the holes before

winding but

every time I get a 'short'.
I have tried a toroid core and that works without the problem.
Interested to know if anyone else has experienced this and if they
found a fix!
73, Steve, G0FUW





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