Envelope-to: dave@picks.force9.co.uk
Delivery-date: Wed, 01 Feb 2006 14:02:37 +0000
From: Warren K2ORS/WD2XGJ <k2ors@comcast.net>
To: rsgb_lf_group@blacksheep.org,  rsgb_lf_group@blacksheep.org
Cc: "Alan Melia" <alan.melia@btinternet.com>
Date: Wed, 01 Feb 2006 14:01:44 +0000
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Subject: Re: LF: XGJ..Decca Litz
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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" <alan.melia@btinternet.com>
> 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: rsgb_lf_group@blacksheep.org 
>   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: rsgb_lf_group@blacksheep.org
>     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: rsgb_lf_group@blacksheep.org<> 
>     >   Cc: LWCA LF Reflector<mailto:lowfer@lwca.org> 
>     >   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>
> 
> 
> 
> 
>