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Author Topic: Regency Marine RDF information  (Read 22580 times)

K2MPW

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Regency Marine RDF information
« on: May 20, 2015, 03:28:18 PM »

I went to the Dayton Ohio Hamcation fleamarket this past weekend. First let me say that every Ham needs to put that trip on their bucket list!

I found a complete Regency Polaris marine "ADF" unit. Most Hams would just call them a Doppler RDF.

The thing was made in the stone age of 1981! The nice part is that it works!

As a non boater the marine receiver doesn't do me any good BUT>>> The RDF part of the box has my curiosity tweaked. I have searched the net high and low only to find ONE source of technical information on the NR7100.

The issue at hand is that guy who has the info wants $45 for a schematic and $75 for a manual. Based on the fact that I paid $20 for the entire system, I'm not too keen on shelling out that kind of dough for a piece of paper of which I'm sure is a copy.

I understand the basic idea of how this thing works. I have located a few points of where demodulated audio is sent to the RDF board. What I'd really like to do is remove the marine receiver, separate the RDF circuits from the receiver and inject RX audio from a separate 146 Mhz radio.

Is there anyone out there in the group that might have a link, suggestion or clue as to how I can get  a roadmap of this thing without paying the piper his due?




Thanks

Michael

KB2UMJ at ya who dot com
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WB6BYU

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RE: Regency Marine RDF information
« Reply #1 on: May 20, 2015, 09:18:17 PM »

Or you could just stick a 10 MHz converter ahead of it to convert the 2m signals up to the
passband of the receiver.  You may have to arrange it to pass DC from the input to the output
if the antenna switching voltage goes up the coax cable.  Another option is to look for the
IF strip - for example, if it is 10.7 MHz then you could feed the IF signal from a 2m receiver
that used the same frequency.


If it is a conventional Doppler (there are some other possibilities) then there should be either
one coax cable and several wires connecting the receiver to the antenna assembly, or several
coax cables.  There may be some switching diodes and filter ahead of the receiver section, but
the first transistor you encounter likely will be the beginning of the receiver, and a possible
point to tap off the signal to the 2m receiver.

The other connection for a Doppler is the audio output - the receiver should have a speaker, and
if you work back from that it should get you pretty close.

K2MPW

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RE: Regency Marine RDF information
« Reply #2 on: May 21, 2015, 04:43:06 PM »

Thanks for the ideas.
The RX in this thing is pure 1981 cheapo. It has all kinds of issues that stem from early microprocessor controlled radios.
I have connected it to a sig gen and sent a 1000 hz tone into it. I poked around and found three different areas that have the demod audio present so I'm still lost as to which one to pick. I guess I could kill off one at a time and inject audio from my 2m rx as an experiment.
Poking around in this thing is fun, but I still would rather have a roadmap, off roading can get tiresome.

Thanks
Michael
KB2UMJ
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AG1B

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RE: Regency Marine RDF information
« Reply #3 on: May 24, 2015, 06:29:18 AM »

The issue of using the Regency Polaris ADF NC7100,7200 on the Ham bands has been raised on the web a few times over the years. I don't believe anyone has reported on a connection that works. Please report on your efforts if you engineer a way to connect into the DF side.  I bought a NC7200 in 1979 for use on a boat. I still have it. It was very advanced at the time, but a few marine channels have changed. It was repaired once by Uniden in Texas who might have bought out Regency. I don't have the service manual. The US Patent office has some block diagrams of the Regency ADF which might help.
The Regency NC6000 ADF adapter is the unit to seek out for ADF use on the ham and VHF public service bands. The NC6000 connects with speaker and antenna cables with FM receiver/transceivers, in other words, plug n play.
The Sitex 525 ADF adapter with a similar antenna is an other sought after plug n play unit that works with 2 meters, also 70cm. If you find a complete working Sitex 525 ADF, antenna, and cables , buy it.
« Last Edit: May 24, 2015, 07:00:10 AM by AG1B »
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K2MPW

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RE: Regency Marine RDF information
« Reply #4 on: May 27, 2015, 10:56:36 AM »

well lo and behold the United States Patent Office came through. the patent is number 4219821. it fully describes the mode of operation as well as gives schematics for the ADF VHF FM direction finding system. the read is rather tough but I found what I was looking for.audio is coupled into the ADF unit through a single capacitor. Although the value of the cap is not called out figure 4c in the patent shows the connectivity of the capacitor to other components so it should be rather easy to find.the other interesting fact is that the ADF unit utilizes a divided down clock signal from the actual Marine Band receiver. That signal is a 40 khz clock videos divided from a10.254mhz ref. That means the marine rx board stays in place.
I hope to play with this very soon and will update when I can.

Tnx
KB2UMJ
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K2MPW

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RE: Regency Marine RDF information
« Reply #5 on: June 09, 2015, 05:25:17 PM »

The good news is that I was able to figure out where the inject point would be. I used a signal generator on ch 16 156.800 with a 1khz tone. After poking around with a scope I found two points on the ADF board (the one closest to the front of the unit). The input to the ADF is at the far right and towards the front of the board. I can't remember what the color was. Looking at the schematic that is listed in the http://www.google.com/patents/US4219821 the input is coupled via a cap and a resistor. The proximity of a pair of to-92 transistors confirmed it for me.
The second location is towards the rear but also on the right. That is the audio output of the ADF that goes to the audio amplifier.
The bad news is that I didn't take it any further than that. I don't think the thing is actually working as well as it is supposed to. From the patent description, the display is supposed to "scan" as long as there is no incoming signal. Well.... it kinda does that but not constantly. It does respond to a signal transmitted from a HT but I just don't get the feeling that it's doing what its supposed to.
For now, I'm holding off playing with it. Because of its age, I may just end up putting it on ebay and make it go away.

73
Michael
KB2UMJ
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