[ARC5] Cleaning and soldering Litz wire?

[Tom Bridgers]

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
> *************************************