RCA phono jacks on Heath gear

[Scott Prather]

Initially, I responded to Jeff directly concerning this question.  However,
after reading all the subsequent posts I thought I'd pass this along to the
group.

Back in the mid 70's the radio club I belonged to in suburban Chicago had a
"Heathkit night" every October, when the salesmen from Heathkit would
arrive to show us their newest equipment.  During one of these meetings
someone asked why they use RCA connectors on their equipment, and their
response was "well, it's good enough for Collins, isn't it?".  After a few
half-hearted laughs from the audience, someone asked "OK, if an RCA
connector is so great, how do you put one onto a piece of RG-8".  They
looked at each other, and then admitted that the prime reason they used the
RCA was the cost difference AND they felt they could get away with that
rational since Collins used the same connector.  Besides, they said, you
can always build an adapter.  If you're prone to worry about impedance
"bumps", that answer makes a lot of sense.

I've heard all the arguments, and I've swept both connector types on a
network analyzer.  Below 30 MHz there is absolutely no electrical
difference between the two worth noting. The question of whether or not one
connector has an advantage over the other concerning an impedance
discontinuity is essentially irrelevant in amateur equipment, and would
only become a concern in precision impedance measurement or fast-risetime
pulse applications (and in either of these applications you wouldn't even
think of using an RCA connector).  Mechanically, these connectors are a
disaster when used in any application where the cable places strain on the
connector.  They were designed to provide a simple, inexpensive connection
at audio frequencies on cables that would place minimal mechanical strain
on the connector.  While it's true that their applications have gone beyond
simple audio applications, this decision has almost always been driven by
their low cost, not their performance.

Scott
N7NB
----------
> From: Jeffrey Herman <jeffreyh at HAWAII.EDU>
> To: BOATANCHORS at LISTSERV.TEMPE.GOV
> Subject: Re: RCA phono jacks on Heath gear
> Date: Saturday, 31 October, 1998 17:27
>
> On Sat, 31 Oct 1998, AL DOLGOSH wrote:
> > The impedance of a coaxial line is a resultant of the ID to OD ratio
and the
> > spacing.  The RCA connector is hardly a coaxial connector.
>
> Doesn't the dialectric between the two conductors play a role, also?
>
> Jeff KH2PZ / KH6
>
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