Nautilus DMC IIb schematic

[Mario-j23]

Thanks, friends. Link to my disk with the collected material. There is also a diagram Nautilus IIB and PCB that I drew. Be careful, it may contain errors. Sorry for my English, I use a translator.
https://drive.google.com/drive/folde...usp=share_link

[kt315]

thank you much MJ23. must do a mix of the files with mine sorted for the archive. you are best amigos, you do your Home Work perfectum.

[Carl-NC]

Yes, I did know the 2Ba had a preamp. I suspect (thinking like a tech) that is how the modern multi frequency machines must be getting away with making the coil resonant at different frequencies, by switching different caps in parallel with the coil at the preamp. I would love to know if I am correct or not. I have a Nokta Legend and looked at the frequency output of it in multi modes. It appears to be a variable pulse width modulated square wave.

Multifrequency designs do not resonate the coil at all, they leave it wideband. Probably all of them have the preamp in the coil, the reason for doing that is to improve the SNR of the signal going up the cable. In that respect, practically all detectors would benefit from moving the preamp to the coil.

[yoyo27983]

Thanks for the file share Mario-23!
Carl, thanks for the note about the modern multi freq coils. I have a lot to learn about how the various coils work. I am a radio tech by trade and an amateur radio operator so I understand why they would put a preamp in the coil. I would have bet they were trying to make the coil resonant for best efficiency. That surprises me! My friend is going to buy a 2Ba in the near future. I can probably get some more information from him. Does anyone have any specific questions? Not sure if he is willing to tear the board out of it for good pictures though.

[Carl-NC]

Single frequency detectors (like the Nautilus) almost always have a resonant TX coil for power efficiency, and almost always run a sine wave. The RX coil can be tuned or not, it's done to decrease EMI noise. In multifrequency, the TX is always wideband and driven with a rectangular waveform. The RX is always wideband.

I'm in the market for a DMC-2B, but not at the price most people want for one.

[Mario-j23]

I did take some measurements with my O'scope and voltmeter which are in the notebook and did not get typed into the word doc. I was also disappointed not to be able to read the components on the autotune Bd.

I can't find the doc or the notes on the google drive. Could you give me any directions where they are if they are even shared?

[yoyo27983]

I can't find the doc or the notes on the google drive. Could you give me any directions where they are if they are even shared?

The notebook is the hand written notes I had taken when I had this on the bench and testing it. They did not get copied into the word doc I had started that is in the folder.

[scrungy_doolittle]

I am not familiar where the Archive is located.

the Archive is on my GOOGLE disc, i give a link above in post.

I can't get there. It appears to take me to a log in page, If I log in using my gmail id, it says that the drive is not accessible because I don't have permission to access it. I guess you need to tag it somehow

[kt315]

on every link to the disc i give here to someone i get 10-20+ requests. while i give to just one. so i can NOT distinguish where is your request or not because all people under nicks. check your SPAM box. i am looking it regularly too.

[kt315]

[giuhalftrack]

this was mine I had two the DMC II and DMC IIa great machine... deep holes ahahahha
I have to find others but my computer is a mess

[kt315]

deep holes

guys, i ask you again, do the pics under open sun at your yard, OUT OF YOUR HOME/ROOM/SHED.
the source of the information is just YOU, not kt315. remember that.

[lokaj81]

Pavol M. alias lokaj 81, kt315 thanks for MET_DET.rar

[kt315]

welcome amigo... i am glad you get whole archive and will look in the perspective )

[giuhalftrack]

deep holes

guys, i ask you again, do the pics under open sun at your yard, OUT OF YOUR HOME/ROOM/SHED.
the source of the information is just YOU, not kt315. remember that.

sorry those are old pictures I don't have the nautilus anymore.