KT88 construction problem

[John Caswell]

Hi all,
A 15 Watt soldering iron is not really big enough for this sort of work. it does not have enough thermal capacity/inertia to keep hot when applied, say, to a valve base tag or a big part tag.
As a minimum I would use a 25 Watt or preferably a welder TCP type 48 Watt, but I appreciate that is an expense many could do without at present. As an an example I have a 15Watt, 25Watt ,2 off 48Watt, a 60 watt and a 125Watt. They are all used at one time or another.
Silver solder versus lead free versus Tin/Lead? I will always stick with Savbit Multicore Tin/Lead. Do not use separate flux paste as some is acidic, which you do not want. To clean flux if required, IPA or Methylated Spirit does the job nicely especially on PCBs.
That should stir things up nicely:-)

John

[FreddieT]

+1 for tin/lead. Stay well clear of lead free (the only acceptable tin whiskers are those left behind by the cat if you leave the food can out).

It's not for no reason that aerospace and military electronics are still using leaded solder.

F.

[bikerhifinut]

I also am no fan of "Lead free" solder. I only used the silver loaded lead free on my WD88 where I was soldering the silver plated connecting wires. The joints never looked properly "wet" the solder always solidifying to a very dull colour. Luckily I didnt seem to have any bad joints.
I shall be very sad when my roll of 60/40 tin lead runs out.

I also tried using normal 60/40 on some wiring in another project with the silver plated wire from WD, it soldered just fine. I think the clue is in "Silver plated" and maybe the silver just melts into the joint and the normal solder "takes" on o the copper strands? May be a different story with Solid silver? I have no experience of this.

In the WD88 I actually used ordinary copper solid core for the link wires on the tag strips, I am just a wee bit cynical about the sonic "benefits" of an inch or less of silver plated wire. I'd rather have neat "wet" joints.
did of course use the supplied wire for the longer wires, especially where it was the heavier duty stuff.

I built the WD88 back in 2007, it worked straight away on switch on and has not needed any surgery apart from a couple of minor upgrades/alterations.
But I was somewhat OCD about the build and took my time to build it. never starting one stage unless I was sure of finishing it.

Andy

[Richard]

Yes I use 62% tin 36% lead 2% silver solder from RS 551-671
Low melting point and flows like water, no grey pudding, great for construction and repairs on copper and silver/plated.
Had the reel for years but it's gone up a lot in price these days

[A.N. Beal]

Dear Guys,
Thanks for the advice. I found that generally I was able to get good joints with the Antex and silver solder but the bit had to be clean and given time to get good and hot and (as you have found out) when I rushed things some didn't work out right. In hindsight the Antex was better suited to the printed circuit boards and trnasistors I was dealing with when I bought it. It reminds me that when I 'helped' my dad to build a Heathkit amplifier when I was about 5 years old his soldering iron was a Henley Solon 25 watt.
Plus ca change ..., was they say in French.
Best wishes,
Alasdair

[david]

Originally Posted by Richard

Yes I use 62% tin 36% lead 2% silver solder from RS 551-671
Low melting point and flows like water, no grey pudding, great for construction and repairs on copper and silver/plated.
Had the reel for years but it's gone up a lot in price these days

Yes, just don't use it on any 6C33 valve bases which operate at 200c with its 179c melting point!