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"Ray Andraka" <ray@andraka.com> wrote in message
news:IH9Zg.7614$XX2.2429@dukeread04...
> Dave S wrote:
> > Ray Andraka wrote:
> >
> >>
> >> I believe the breakers are supposed to be sized to the wire, not to
> >> the radio. My transponder (was an AT150 with a trans-cal encoder, now
> >> an AT165) has a 5A circuit breaker on it.
> >
> >
> > Ray.. as many others have told me.. you are right.. you size the breaker
> > to the wire.. not the device..
> >
> > But you also size the wire being used.. to the current carried over the
> > distance carried (as the nice lil FAA book shows)...
> >
> > So one sizes the wires to the device,, then the breakers to the wires..
> >
> > In my instance it makes a difference because I've a LOT of 5 amp
> > breakers. For the wire runs involved, a 1, 5 or even 10 amp breaker will
> > protect my wires adequately. But I also dont want to pop a breaker in
> > normal operation.. "while protecting my wiring run"
> >
> > By they way.. thanks for the feedback on the 5A breaker.
> >
> > Dave
>
> I believe Narco has the install manual on their website.
>
> The install manual calls for a 1.5A circuit breaker. They list the power
> requirements as 1.0A receive, 1.6A transmit, 0.26A pilot lights. I can
> tell you that when I bought my airplane, the fuse (changed out for
> circuit breakers since then) for the transponder was marked 1.5A. That
> circuit feeds just the transponder and encoder. I had constant problems
> with it blowing 1.5A fuses, not always but within a couple hours. I
> took it to "the Radio Shop" in Worcester MA, who was a master service
> center for Narco before Narco pulled service in house. They took one
> look at the install, and said the problem is the 1.5A fuse isn't
> sufficient for that encoder's heater and that the 1.5A was what Narco
> recommended for just the transponder. They checked the wiring to verify
> no chafing and that it didn't go anywhere else, measured the current
> with and without the encoder, and then remarked the fuse holder for 5A.
You are correct, and thanks for the link which I've now saved.
http://www.narco-avionics.com/
Choose "Manuals and Pinouts" and the AT-150A has a 17 page pdf manual.
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Re: Sizing the CB needs... Homebuilt wiring too
