[ARC5] Cleaning and soldering Litz wire?

Tue Jun 11 11:03:27 EDT 2013

You can buy a Chinese mini soldering pot for about $10 on Fleabay.

Dip the Litz into a diluted hydrochloric acid, sold as plummers tinning 
fluid, Muriatic acid, etc and into the molten solder.

Then dip the Litz into a mix of baking soda and water to neutralize the 
acid......just as you do with automotive batteries.

> Hi Ken,
> I'm 71 years old, have shaky hands, not so sharp eyesight
> anymore, and still like to solder.  But have never had much
> success with cleaning and soldering Liitz wire.
>
> Mostly I wind up breaking the wire by the time I have
> enough covering removed to solder.   What steps/procedures
> have you found that work the best to get Litz wire ready
> for soldering?
>
> Great posting about finding and solving the 70+ year error
> in the ARC-5 Rx and getting it to work again!
> Thanks,
> -Tom KE4RHH
> > Message: 3
>> Date: Tue, 11 Jun 2013 00:44:32 -0000
>> From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
>> To: ARC-5 List <arc5 at mailman.qth.net>
>> Subject: [ARC5] 70+ year old errors found and corrected.
>> Message-ID: <51B672F0.32671.67E6D7A6 at kgordon2006.frontier.com>
>> Content-Type: text/plain; charset=US-ASCII
>>
>> You know that 1.5 - 3.0 MHz coil box I was having troubles with? The one 
>> out of the receiver
>> that had been hacked for crystal control back in the 1970s?
>>
>> Well, today, not having anything much else to do (yeah, right), I decided 
>> to take a closer look
>> at it to see if I could figure out exactly what was wrong with it.
>>
>> First, since the HFO coil had been the one that had been messed with (I 
>> figured this out
>> when I looked at the screws holding the coil in the box: there were 2 
>> different kinds, and the
>> paint had been "broken").
>>
>> Although I had restored the two resistors, R-3 and R-6 to their original 
>> values, the HFO still
>> didn't work. I looked more closely at the connections to the coils and 
>> after taking my glasses
>> off and looking VERY closely, I discovered that one lead of the plate 
>> coil was no longer
>> soldered to its connection. What looked at first like solder was flux, 
>> and all 6 of the Litz wires
>> were not soldered. When I had tested the coils for continuity, I had 
>> clip-leaded one lead of the
>> ohm-meter to one end of the coil, and had used the probe on the other 
>> end. The clip-leaded
>> end turned out to be the open one....of course.
>>
>> Have any of you 70+ year old folks ever attempted to 1) clean the enamel 
>> off of 6 pieces of
>> #60 Litz wire, and then 2) solder them in place with shaky hands? Well, I 
>> managed...finally.
>>
>> Putting it all back together and installing in my working receiver, I 
>> found that the HFO was
>> now working, but the signal through the mixer was way down. However, the 
>> RF amp did peak
>> by the Align Input control, so that meant that the RF amp coil was OK.
>>
>> Back to the coil box. After swapping the good coils, one at a time from 
>> my working coil box
>> into the non-working coil box, I zeroed in on the mixer coil as the 
>> culprit. Obviously, however,
>> the coil had never been tampered with as the screws still had their red 
>> paint on them and
>> they were very tight.
>>
>> Even so, I removed them with some effort, and removed the coil. Using my 
>> clip-lead and
>> ohm-meter I again determined that both coils had continuity. Furthermore, 
>> there were drops
>> of the original ruby-red enamel on all the connections.
>>
>> Then, remembering my experience with the HFO coil, I used both of the 
>> ohm-meter probes,
>> without any clip-lead, to check continuity through the connections at the 
>> bottom of the coil
>> from outside it.
>>
>> Sure enough: one coil no longer had continuity.
>>
>> Again removing my glasses, I looked VERY closely at the two connections 
>> of the now open
>> coil, both of which looked "factory" and both of which had that ruby-red 
>> enamel on them.
>>
>> One of those connections had never been soldered: the Litz wire had been 
>> wrapped around
>> the connection, never soldered, and then had been covered with ruby-red 
>> quality-control
>> enamel.
>>
>> A 70+ year old construction error, followed by a quality-control error 
>> uncovered.
>>
>> A few seconds with the soldering iron and solder fixed the problem.
>>
>> Re-installing the now repaired coil box proved that the receiver was now 
>> working properly.
>>
>> Alignment followed, and I am now listening to it.
>>
>> Sheesh!
>>
>> Ken W7EKB
>>
>>
>> ------------------------------
>>
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>>
>>
>> End of ARC5 Digest, Vol 113, Issue 46
>> *************************************
>
>
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