[time-nuts] 58517A external SMC power versus PORT1 power

[Magnus Danielson]

From: "Christopher Hoover" <ch at murgatroid.com>
Subject: [time-nuts] 58517A external SMC power versus PORT1 power (was Re: HP Z3801A on eBay -- And check this out as)
Date: Sat, 20 Jan 2007 15:47:44 -0800
Message-ID: <000401c73ced$61804360$ab01000a at fakie>

> 
> > Well, I failed to have my Z3801A drive my 58517A over port 1.
> > Appling 5V on the SMC connector on the 58517A solved the 
> > problem. The same Z3801A was feeding the active antenna with
> > no problem just a few minutes before, so it is not an issue on
> > the Z3801A.
> 
> I've got/had both varieties, and some time ago I mapped out the circuits.
> 
> To be clear (for non-smart spliiters):
> 
> If it has the SMC jack, external DC power must be supplied via the SMC jack.

As I suspected.

> All of the output ports will sink some current to make receivers happy, but
> they will not power the amplifier.

Good.

> If it doesn't have the SMC jack, power must be supplied via PORT 1.  All of
> the other ports will sink current to make receivers happy, but they will not
> power the amplifier.
> 
> It is easy to convert the external DC version to work with DC on PORT 1.  It
> just takes a (1206, IIRC) shunt -- the pads are right there near PORT1.  It
> is a good idea at the same time to pull the current limiting resistor in
> series with SMC jack so as to disable that input.

Another approach would be to insert diodes such that either the SMC or Port 1
may be used.

Cheers,
Magnus