[volt-nuts] Good quality but reasonably priced 4mm plugs?

[Tony]

On 16/08/2014 11:24, Andrea Baldoni wrote:
> On Sat, Aug 16, 2014 at 12:44:53AM +0100, Tony wrote:
>
>> Can anyone recommend some decent banana plugs, preferably stackable,
>> for making up test leads? There don't appear to be many different
>> types on Ebay - the cheapest have a single screw connection which
>> loosens off at the drop of a hat, and in any case the plug, at 16mm,
>> is too short for my HP 34401A.
> Hello Tony.
> Gordon already recommended the same kind of plugs I use, but I think
> it would be better if you buy them from the manufacturer, because
> I found many cheap imitation around there and they are really not the same.
>
> They are made by Hirschmann, and if you prefer the solder/crimp version,
> you should buy the BUELA 30. Red color is 930727101 and black 930727100.
> They make also the female KUN 30 and the male BUELA 300 with lateral insulation
> to avoid unwanted contacts when coupling them.
>
> I normally buy them from Farnell, where you could also find the SLS425-SE/Q
> that suggested Todd.
>
> Best regards,
> Andrea Baldoni
Thanks everybody for all the suggestions - I have to say I didn't expect 
it to be quite so difficult.

Gordon: That ebay suggestion looks good but they're out of stock. The 
description doesn't say if they are gold plated (my preference) or not - 
they look as though they are in two photos but not in the other.

Andrea: I found the Hirschmann BUELA 30s here: 
http://www.conrad-electronic.co.uk/ce/en/Search.html?search=BUELA - the 
price is reasonable at  £0.79 each ($1.3), but they are nickel plated 
and I would prefer gold plated. I have to agree with your suggestion to 
buy branded products given the poor quality of some Chinese ebay goods, 
but some of it is perfectly ok - its pot luck.

Todd: The SLS425-SE/Q is available from Farnell but they are shielded 
which isn't what I'm after (sorry, I forgot to mention that) and aren't 
that cheap at £3 each (+ 20% VAT) and you have to buy them in packs of 5 
of one colour. The Multi-Contact SLS205s are gold plated and aren't 
shielded but aren't stackable.

The Multi-Contact SLS425-A looks like a possibility; its still a bit 
short at 18mm but its gold plated, solder connection, stackable and cost 
£1.59 including VAT from conrad-electronics. (I don't know anything 
about them but they do seem to have an large range of connectors).

I might have to buy low thermal cables as I haven't yet found any 
suitable banana plugs - ie. gold plated, crimp and solder connections 
and made from copper with a copper based spring. (Some have 
copper-beryllium springs but brass bodies). How are the ready made low 
thermal leads connected - are they soldered, crimped or both? My concern 
with crimped connection is that despite a good tight connection, the 
copper wires in the joint may still be prone to oxidation leading to 
high thermal emfs and even rectifying properties?

Can anyone tell me how long the plug is on HP test leads? The first 8mm 
or so is lost to the contacts being recessed in the test socket on the 
34401A.

On gold plated contacts:

I found this interesting: 
http://www.te.com/documentation/whitepapers/pdf/aurulrep.pdf
They claim gold to be the best connector coating with 2 exceptions:

1) They shouldn't be mated with tin contacts
2) They aren't recommended for making/breaking live circuits due to the 
susceptibility of the gold contact to arc damage.

I wasn't aware of these and will be more careful in future - 
particularly when undertaking current measurements with my HP 34401A to 
avoid damaging the terminal sockets.

Tony H