I have some projects with 300b SET amps built on two chassis - power
supply and signal chassis. Right now I'm using amphenol 4 pin AP
series connectors for earth and HT - which is about 440v or 490vDC off
load.

I'm wondering about a simpler coax option, since I really only need HT
and earth (rest can be done with 4/5 pin XLRs and 4/8 pin speakons).
The umbilical can be fixed at the PSU end and detachable at the signal
chassis. So a female socket on the cable and a male one on the
chassis.

I have no experience of coax connectors - there's the cheap and
plentiful BNC, the more robust N type, then TNC, UHF etc etc. The
connector must be comfortable at 500v, but the other requirement would
be that the cable connector - presumably female - should be
sufficiently shrouded that it's very hard to touch since there's over
400vDC on it!!

Best choice here?

andy

"Andy Evans" wrote in message
...

Best choice here?

Err. stay with what you've got?

Why do you want to change? and why do you think co-ax appropriate for DC?

And if you are using 5-pin XLRs for "the rest" why not use them for this as
well?

Your whole approach seems arbitrary and illogical.

David.

In article
,
Andy Evans wrote:
I have some projects with 300b SET amps built on two chassis - power
supply and signal chassis. Right now I'm using amphenol 4 pin AP
series connectors for earth and HT - which is about 440v or 490vDC off
load.

I'm wondering about a simpler coax option, since I really only need HT
and earth (rest can be done with 4/5 pin XLRs and 4/8 pin speakons).
The umbilical can be fixed at the PSU end and detachable at the signal
chassis. So a female socket on the cable and a male one on the
chassis.

I have no experience of coax connectors - there's the cheap and
plentiful BNC, the more robust N type, then TNC, UHF etc etc. The
connector must be comfortable at 500v, but the other requirement would
be that the cable connector - presumably female - should be
sufficiently shrouded that it's very hard to touch since there's over
400vDC on it!!

Best choice here?

If you want posh go for Lemo. They make co-ax connectors suitable for high
power transmitters where I'd guess there are a fair few volts flying
around. But be prepared to dig deep...

--
*A bicycle can't stand alone because it's two tyred.*

Dave Plowman London SW
To e-mail, change noise into sound.

"Andy Evans has no Brain"

I have some projects with 300b SET amps built on two chassis - power
supply and signal chassis. Right now I'm using amphenol 4 pin AP
series connectors for earth and HT - which is about 440v or 490vDC off
load.

I'm wondering about a simpler coax option, since I really only need HT
and earth (rest can be done with 4/5 pin XLRs and 4/8 pin speakons).
The umbilical can be fixed at the PSU end and detachable at the signal
chassis. So a female socket on the cable and a male one on the
chassis.


** Using an RF co-ax connector for this job is totally insane !!!!

None of the readily available types are even vaguely safe as they allow
finger contact with the core terminal.

No readily available connector is entirely safe for delivering high voltage
DC and earth to an exposed chassis. There is far too much risk that due to
damage, normal wear and tear or partial insertion of the line plug in the
socket a situation arises where the DC power ground ( ie chassis earth ) is
NOT connected while the high voltage DC is.

This event will render the amp chassis live and lethal.

The same rules apply as with any mains powered appliance that requires a
safety earth - particularly that the safety earth conductor MUST NOT also
be a current carrying conductor.

Speakon ( and PowerCon ) connectors have the unfortunate characteristic
that the back cover unscrews in the fingers and exposes internal live
arts - makes them quite unsafe for use as domestic mains power or high
voltage connectors. The Speakon twists to actually connect the contacts -
making it very possible for a partial twist to connect the high voltage DC
contacts but not connect the ground contacts.

The only suggestion I have is to stick with the Amphenol 4 pin AP connector
and use 3 out of the 4 pins to carry the ground conection back to the PSU.
Make sure the cable has 4 wires in it for complete redundancy.


...... Phil

On Sat, 3 Oct 2009 15:15:28 -0700 (PDT), Andy Evans
wrote:

I have some projects with 300b SET amps built on two chassis - power
supply and signal chassis. Right now I'm using amphenol 4 pin AP
series connectors for earth and HT - which is about 440v or 490vDC off
load.

I'm wondering about a simpler coax option, since I really only need HT
and earth (rest can be done with 4/5 pin XLRs and 4/8 pin speakons).
The umbilical can be fixed at the PSU end and detachable at the signal
chassis. So a female socket on the cable and a male one on the
chassis.

I have no experience of coax connectors - there's the cheap and
plentiful BNC, the more robust N type, then TNC, UHF etc etc. The
connector must be comfortable at 500v, but the other requirement would
be that the cable connector - presumably female - should be
sufficiently shrouded that it's very hard to touch since there's over
400vDC on it!!

Best choice here?

andy

Have a look here, you should find something safe that will fit the
bill. Not cheap though, I'm guessing.

http://www.ges-electronic.com/connector/multipin_hv.php

d

In article , Dave Plowman (News)
wrote:
In article
,
Andy Evans wrote:

I have no experience of coax connectors - there's the cheap and
plentiful BNC, the more robust N type, then TNC, UHF etc etc. The
connector must be comfortable at 500v, but the other requirement would
be that the cable connector - presumably female - should be
sufficiently shrouded that it's very hard to touch since there's over
400vDC on it!!

Best choice here?

If you want posh go for Lemo. They make co-ax connectors suitable for
high power transmitters where I'd guess there are a fair few volts
flying around. But be prepared to dig deep...

I'd agree with the above since IIRC Lemo make designs specifically for high
voltage uses, and they can provide self-locking. That, combined with being
totally incompatable with the usual audio plugs would help avoid accidents.
You will, of course, have to also choose a cable that is designed for high
DC voltages.

Lemo do tend to be expensive - but cheap if they save your life.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Hello again,

Thanks for the contributions. I'll answer the questions first! David
Looser - nothing is either arbitrary or illogical here. The connectors
are chosen for the following criteria:
1) They are cheap and widely available. So Don and Dave - yes, plenty
of Lemo and Amphenol to drool over! You have my sympathies here! But I
arrived at Amphenol AP because it was a much cheaper option for the
voltage required, while being available from most suppliers.
2) They carry voltages within their voltage rating. Here, David, note
that XLRs are now rated as 50v. They were rated at 300v or so but have
been re-rated in conformity with newer regulations, so XLRs are now
not an option for high voltages. So they are used for filament
voltages. Speakons are rated 300v. They could no doubt carry more but
I'm using an Amphenol AP connector because it's rated 660v.
3) They are not confused with other connectors. So 3 pin XLRs are out
for power supplies, 4 and 5 pin are possible. Speakons could
theoretically be an issue but they are only used on the power supply
where they are fixed to the chassis. There's no power on the signal
chassis end so you couldn't connect a speaker to it unless the amp had
no power to it.
4) They are safe in use - fingers can't touch live parts. Speakons are
nice here because shrouded, but they don't have the voltage rating for
490v. Yes the backs unscrew, though when you screw them up tight they
are pretty hard to unscrew. A theoretical hazard maybe, but well
noted. Thanks for pointing that out, Phil.

So having arrived at the current solution by careful logic, it's a
good question "why change it"! I don't have to - it works perfectly
well. The amphenol connectors are nice and easy to use, though a
little large.

The advantages of a coax connector is that I could buy already made up
leads, which would save time. Now this is where Phil is very
informative - thanks Phil!
None of the readily available types are even vaguely safe as they
allow finger contact with the core terminal. This was indeed my
question. I haven't handled these connectors so I'm only going by
photos - you can't handle a photo so I don't know what can and can't
be touched.

So you reckon - as above - that all these coax connectors could be
touched? That would rule them out really if that's the case.

So again Phil says stick with the Amphenol. Earth and HT connect
simultaneously, earth is a nice big size. Cable is rated for 1,000v.
Of the 4 connections two are for HT and earth, and one is for fixed
bias if used, so typically -30v or something. So I do have one
connection available. So what is the suggestion of carrying the ground
connection back to the PSU? How is this implemented and what's the
advantage?

andy

"Andy Evans is Totally Brain Dead "


I'm using an Amphenol AP connector because it's rated 660v.


** Fraid the maker says the connector is only *safe* for 50 volts.

http://www.amphenolaudio.com/catalog.../page77_78.pdf

See note 1.


Christ alive - the Evan pommy puke is one PIG ARROGANT MORON !!!



...... Phil

"Phil Allison" wrote in message
...

"Andy Evans is Totally Brain Dead "


I'm using an Amphenol AP connector because it's rated 660v.


** Fraid the maker says the connector is only *safe* for 50 volts.

http://www.amphenolaudio.com/catalog.../page77_78.pdf


It says:

"Not suitable for domestic applications above 50V".

This is because it is possible to touch the female contacts with a bit of
wire or something, which is the sort of thing an unsupervised child might
do. If there is no possibility of the uncoupled connector being accessed
when powered is applied, then this restriction does not apply.

David.

On Sun, 4 Oct 2009 01:23:01 -0700 (PDT), Andy Evans
wrote:

Hello again,

Thanks for the contributions. I'll answer the questions first! David
Looser - nothing is either arbitrary or illogical here. The connectors
are chosen for the following criteria:
1) They are cheap and widely available. So Don and Dave - yes, plenty
of Lemo and Amphenol to drool over! You have my sympathies here! But I
arrived at Amphenol AP because it was a much cheaper option for the
voltage required, while being available from most suppliers.
2) They carry voltages within their voltage rating. Here, David, note
that XLRs are now rated as 50v. They were rated at 300v or so but have
been re-rated in conformity with newer regulations, so XLRs are now
not an option for high voltages. So they are used for filament
voltages. Speakons are rated 300v. They could no doubt carry more but
I'm using an Amphenol AP connector because it's rated 660v.
3) They are not confused with other connectors. So 3 pin XLRs are out
for power supplies, 4 and 5 pin are possible. Speakons could
theoretically be an issue but they are only used on the power supply
where they are fixed to the chassis. There's no power on the signal
chassis end so you couldn't connect a speaker to it unless the amp had
no power to it.
4) They are safe in use - fingers can't touch live parts. Speakons are
nice here because shrouded, but they don't have the voltage rating for
490v. Yes the backs unscrew, though when you screw them up tight they
are pretty hard to unscrew. A theoretical hazard maybe, but well
noted. Thanks for pointing that out, Phil.

So having arrived at the current solution by careful logic, it's a
good question "why change it"! I don't have to - it works perfectly
well. The amphenol connectors are nice and easy to use, though a
little large.

The advantages of a coax connector is that I could buy already made up
leads, which would save time. Now this is where Phil is very
informative - thanks Phil!
None of the readily available types are even vaguely safe as they
allow finger contact with the core terminal. This was indeed my
question. I haven't handled these connectors so I'm only going by
photos - you can't handle a photo so I don't know what can and can't
be touched.

So you reckon - as above - that all these coax connectors could be
touched? That would rule them out really if that's the case.

So again Phil says stick with the Amphenol. Earth and HT connect
simultaneously, earth is a nice big size. Cable is rated for 1,000v.
Of the 4 connections two are for HT and earth, and one is for fixed
bias if used, so typically -30v or something. So I do have one
connection available. So what is the suggestion of carrying the ground
connection back to the PSU? How is this implemented and what's the
advantage?

andy

You can use that one spare connection for ground, but is that
something different from the one you already nominate as Earth? Not
too clear about that.

d