[RFI] tracking RFI with a marine direction finder

[Dennis Monticelli]

Yes.  All true, Jim.  Thanks for highlighting those features.

The ability to eliminate the bidirectional ambiguity of the ferrite rod via
the Sense whip antenna is highly useful.  The pseudo BFO will disappoint
hams but it's ability to place an audio tone marker on any carrier one
tunes across is still useful.  The designers built the BFO that way so the
lay person would find it easier to stop on the carriers of weak Beacons or
AM stations.

FYI. The same exact receiver goes under the brands Newmar, Coastal
Navigator,  Maricom 1, and FR-662B.  It's an eleven transistor superhet
with an RF stage and a ceramic filter in the IF.  Easy to repair if
necessary.  Not light like a Pilot but there's a side handle.

Dennis AE6C

On Wed, Jan 27, 2021 at 8:47 PM AA5CT <jwin95 at yahoo.com> wrote:

>
> Do not under-sell the usefulness the cardioid (unidirectional) antenna
> pattern
> adds (via the "Sense" antenna function) when DFing noise or other signals
> when using a Coastal Navigator/NAV 101 receiver.
>
> Riding a bicycle and continually 'rotating' the cardioid antenna I can
> practically
> 'drive up to' any interfering signal on the 160 or 80 meter bands when
> DFing
> same.Using a loopstick alone (with only nulls to go by) is a little
> trickier.
> Nowadays I feel quite confident when taking compass bearing readings
> for later plotting when using the Coastal Navigator/NAV 101 DF receivers,
> first confirming the direction of the source using Sense and then refining
> with a null (if sufficient signal strength allows). ALSO NOTE the ferrite
> rod antennas in these units employ internal shields to eliminate E-field
> response and/or interactions with the operator's hands when in proximity
> with the rotatable ferrite bar antenna..
>
> About the Pilot - The Pilot lacks the Sense antenna feature that the
> Coastal Navigator/NAV 101 DF receivers have. I have a couple of these too,
> but be CAREFUL when putting the batteries into the holder. There are
> markings for Mercury batteries which in the day had little 'posts' on the
> opposite of what we expect today (polarity is reversed) and the marking
> on the batt holder can be confusing. Incorrect insertion of the batts can
> kill the receiver.
>
> Also, I have found that the Coastal Navigator is the ONLY Marine DF
> receiver that has a functioning Sense antenna feature. The Benmar/Bendix
> series model 555 Sense function does not operate, and neither does the
> Sense function on the one model (6140) Ray Jefferson I have. A couple
> of us here locally have owned the Bendix/Benmar model 555's and the
> Sense feature did not work on any of them.
>
> Additionally, the so-called "BFO" on the NAV 101/Coastal Navigator
> modulates the final IF amplifier with a 400 Hz tone so a CARRIER ends
> up with a tone on it; this does NOT aid on SSB reception.
>
> de AA5CT/Jim
>
>
>
>
>
>
>
> On Wednesday, January 27, 2021, 8:12:13 PM GMT-6, Dennis Monticelli <
> dennis.monticelli at gmail.com> wrote:
>
>
>
>
>
> Scott,
>
> Yes, the Pilot series is good and easy to lug around too.  Like the others,
> they are inexpensive.  I have one awaiting restoration.
>
> Dennis AE6C
>
> On Wed, Jan 27, 2021 at 5:56 PM nm8rmedic <nm8rmedic at rocketmail.com>
> wrote:
>
> > Another good portable RDF is the Pilot Pal series, with its long
> > rotateable ferrite rod antenna and S-meter.  Same NDB/MW/Marine Band
> > coverage.  The model I have, Pilot II, also has a DF level potentiometer.
> > Scott.
> >
> >
> >
> > Sent via the Samsung Galaxy S8+, an AT&T 5G Evolution capable smartphone
> >
> >
> > -------- Original message --------
> > From: Dennis Monticelli <dennis.monticelli at gmail.com>
> > Date: 1/27/21 18:18 (GMT-05:00)
> > To: rfi at contesting.com
> > Subject: [RFI] tracking RFI with a marine direction finder
> >
> > All,
> >
> > Another useful and inexpensive tracking tool is a vintage marine
> direction
> > finder.  My particular model (Newmar NAV 101, but sold under many a
> private
> > label) is battery powered and has three bands: Beacon, BCB, and Marine
> (1.6
> > to 4MHz).  It has an RF gain control, sig strength meter, a BFO of sorts,
> > and of course a big lovely azimuth calibrated rod antenna that is capable
> > of nice nulls.  I found mine on the local CraigsList but there is always
> > eBay.  Many different makes and models were made.
> >
> > Dennis AE6C
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