[RFI] tracking RFI with a marine direction finder

[Grant Saviers]

One RDF not mentioned, that was my favorite on board, is the Lokata 7 
hand held with a very good built in compass.  LF (marine/aero) and BCB 
only with digital frequency readout.

https://www.ebay.com/itm/Lokata-7-Vintage-Marine-Radio-Direction-Finder-RDF-Hand-Bearing-Sestrel-Compass-/224210468351


Grant KZ1W
On 1/27/2021 20:47, AA5CT via RFI 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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