Hi Alan,
The Decca Litz I used was from the transmitter tank coils, not the external
antenna loading coils. The Decca TX I got from Andre N4ICK (Andre got it from
David G0MRF) was originally on 70.233 kHz. I had to both decrease the tank
capacitance and the inductance to maintain Q. The wire I used for the
transformer came from turns I took off one of the tank coils.
--
73 Warren K2ORS/WD2XGJ
FN42hi
http://www.w4dex.com/wd2xgj.htm
-------------- Original message ----------------------
From: "Alan Melia" <[email protected]>
Hi Mike and all, you need to be a bit carefull talking about the Decca Litz,
because the coils were substantially air spaced. They are not solenoid wound,
but more like a basket wind. There were several parallel strands of wire,
"wavewound" on large formers with, I would estimate (I have disassembled my
coil), about 0.5in. between layers ( plus the lateral distance of wavewind) So
It was not dependent on the insulation. I have some Litzwire from that source
that has only cotton insulation (DCC) but i dont know what this was used for.
The wire on the coils has a thin plastic sheath over the cotton, but I think
this is only intended for mechanical strength to protect the cotton cover during
the winding process, and subsequent chaffing on the perspex (Lucite ??)
separator "combs".
Cheers de Alan G3NYK
----- Original Message -----
From: MIKE REID
To: [email protected]
Sent: 01 February 2006 06:25
Subject: Re: LF: XGJ
So it appears to be a dielectric breakdown in one of the insulations of one or
both of the core windings. Has anyone done a dielectric test on the Decca Litz
wire? I did some on #12 THHN wire a couple years ago and it arced at 5kv AC at
1kc as well as 5kv DC. No burning but it made some Ozone smell and the frying
sound. I'll have to do some hi-pot tests Wednesday on the #12 Teflon insulated
wire I have on my transformer.
This is good information to know. Hopefully others down the road can use this
data to design their LF stations.
Mike
WE0H
WD2XGI
----- Original Message -----
From: Warren K2ORS/WD2XGJ
To: [email protected]
Cc:
Sent: Tuesday, January 31, 2006 8:25 PM
Subject: Re: LF: XGJ
Mike,
The 50 ohm side was made up of Litz wire from the Decca tank coil. The
loop side was #4 stranded wire with pvc insulation.
After examining the transformer close up it appears that the transformer
arced from primary to secondary. This seems to be correlated with the damp rainy
weather yesterday, the transmitter was running full power for 6 and a half hours
before the transformer arced over.
--
73 Warren K2ORS/WD2XGJ
FN42hi
http://www.w4dex.com/wd2xgj.htm
-------------- Original message ----------------------
From: "MIKE REID" <>
> What type of insulation & wire gauge did you have before?
>
> Mike
> WE0H
> WD2XGI
>
> ----- Original Message -----
> From: Warren K2ORS/WD2XGJ
> To: [email protected]<>
> Cc: LWCA LF Reflector<mailto:[email protected]>
> Sent: Tuesday, January 31, 2006 5:18 PM
> Subject: Re: LF: XGJ
>
>
>
> Hello the list,
>
>
> I disassembled the toroidal transformer in the loop ATU and found
the
> cores to be good. I will attempt to pick up some teflon insulated wire
tomorrow
> and rebuild the transformer, if all goes well will be back on the air
tomorrow
> evening.
>
> --
> 73 Warren K2ORS/WD2XGJ
> FN42hi
> http://www.w4dex.com/wd2xgj.htm<http://www.w4dex.com/wd2xgj.htm>
>
> -------------- Original message ----------------------
> From: (Warren K2ORS/WD2XGJ)
> > Hello the list,
> >
> > Many thanks for all the reports last night from Hartmut, Jean-Pierre
> (F5YG),
> > Juan, Gary, and Roelof (Hope I didn't miss anyone!)
> >
> > As many of you have noted the signal dropped off at 03:00 UTC. At
04:00 I
> > noticed XGJ was very weak on the W3EEE 'grabber'. I went downstairs to
the
> radio
> > shack to investigate. The antenna current (measured at 50 ohms) was
less
> than
> > 100 mA ! It should be approximately 5 Amps from the Decca PA. I
checked the
> > Decca on a dummy load and it was ok. I tried the smaller transmitter
and
> noticed
> > a very high SWR. I went out and looked at the ATU, flashlight in hand.
The
> > secondary of the toroidal step down transformer had arced and burned
through
> the
> > insulation. I believe that the very high humidity played a part in the
> breakdown
> > of the insulation. I will have a look at the transformer today and
may be
> able
> > to repair it if the toroidal core is not damaged. I am hopeful that
the
> core is
> > o.k. since impedance measurements showed no change and I was able to
run the
> 250
> > watt transmitter into the antenna with a low swr after a period of
time
> (after
> > the tuner cooled down).
> > I will of course use better insulated wire for the high voltage!
> >
> >
> >
> > --
> > 73 Warren K2ORS/WD2XGJ
> > FN42hi
> > http://www.w4dex.com/wd2xgj.htm<http://www.w4dex.com/wd2xgj.htm>
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