Handwritten code made with Cute-HTML
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A collection of  NRD-515 oriented
diagrams and modifications
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Drawings are NOW in 2-colour BW 600 DPI TIFF format with LZW or G4 compression.
They are very hi-res! Also inside the PDF's ( double compressed LZW + G4)
If they won't view in your IE-browser, copy to HD first!
View with an image viewer like Irfan!!
DO NOT / NEVER
reduce in pixel size! Because they won't print as detailed.
Latest change: Highres GIF replaced by Highres TIFF with LZW compression,
in the PDF's even double with extra G4 over the LZW!
Most in A3 size and rescanned in 600DPI Black&White!
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| Links to original |
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NRD-515 drawings: |
| Item (All 2 colour 300 or 600 DPI High Res TIF files) |
Highres TIF
in PDF file |
Original
TIFF file |
| Principal working overview diagram |  | Appendix 1 |
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| Main chassis and Front Board circuit diagram | | Appendix 2 |
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| Rx board circuit diagram | | Appendix 3 |
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| Synthesizer board diagram | | Appendix 4 |
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| Power supply - voltage distribution between IC's | | Appendix 5 |
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| Power Supply regulator board | | Appendix 6 |
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Anti mains rattle feedthrough rectifiers on regulator board
Adding extra capacitors on the AC side of the rectifiers
Modified version
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Safety modifications mains filter to comply with new regulations
IEC power input exchange with real mains-inlet filter
Click on IE icon to see a sub page with mains-inlet pictures |
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A PDF (only) version of the CPA-94 main tuning dial encoder board
Thanks to cooperation with PA0A (Ex: PA0AWN) who did the research |
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| A PDF (only) version of the CGA-68 main (triple) VCO unit
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A PDF version of the CGA-94, the JST-100 triple VCO unit.
Compare this with the above CGA-68, the CGA-68 decoupling has been improved.
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A redesigned PDF (only) version of the 455 kHz filter board
Due to public demand I made my own layout
Meant to etch your own filterboard!! |
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A very slow FTP link to the complete NRD-515 instruction manual
With all the A3 diagrams inclusive!! All 600DPI, size about 5 MB |
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| Links to original |
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NDH-518 drawings: |
| Item |
Highres TIF
in PDF file |
Download TIF
LZW or G4 |
| Memory Unit NDH-518 circuit diagram (made from TIFF-LZW) |
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Modified memory unit diagram (for the options/modifications further below)
made from TIFF-G4 |
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Complete scanned NDH-518 Memory unit instruction manual
With A3 diagram inclusive |
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Complete scanned original NDH518 Service Manual, scanned not in the most ideal settings according to the latest standards, but this is all that is available!!!
Thanks to Mike - VK4GV |
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GOTO
NWG-515
Remote VFO section
on this page
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NCM-515 |
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←←← LOOK, LOOK, AAAHHHH
Click over here for a scanned NCM-515 manual. Made with an Acro-7 scan plugin,
but compatible with Acro 5 and above.
I've added the very hard to obtain diagram of the connector box CQE-515 as last page.
Also read my Addendum for the NCM-515 manual
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CQE-515 |
CQE-515 |
Click over HERE for lots of PDF files about hardware used in the NRD-515 and in my designs.
And now some links to my modification drawings and designs |
©CopyRight, modifications add-on design, drawings, photographs,
gal programming, and research by: W.A.J. Geeraert ( PE1ABR ) email
Almost all the drawings are made available in PDF format.
You MUST have Adobe Acrobat reader installed, see at the bottom of this page.
I try to keep PDF's compatible as low as AR version 5, some even AR3 !
If problems: copy PDF files to harddisk first without double click, but with "copy to"
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A very simple method to Backup the Synthesizer:
BFO control only for BFO/BC-tune button with Auto BC Tune:
English Dutch Diagram BC-Tune D/A converter and amplifier
BC-tune PCB layout - both sides
ZIP file with example eprom file + QuickBasic 4.5 eprom creation programs - comments in DUTCH
A new version of the Auto BC Tune with more recent DA-converter:
(And a NEW VB6 conversion shell)
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English Dutch Diagram BC-Tune D/A converter and amplifier
new BC-tune PCB layout - both sides
New ZIP file with example eprom file + NEW Visual basic 6 EPROM creation program - And a part of the program listing from VB6 - comments in DUTCH, with simple English Notepad HELP file.
Diagnostic output with over 1000 lines of calculation results.
Due to this list with tune info some minor roundup bugs removed.
If your XP or W2K is very "clean" you also need
the VB6 RUNTIME and dialog files
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Memory NDH-518:
Modifications executed on a NDH-515 Memory unit:
Accessibility Modification on a NDH-518 unit to make it
into a Remote controllable Memory:
AM detector buffer:
The single diode AM detector causes a too high a-symmetric load on the last IF stage.
With a small buffer with low Z-out the distortion is gone, also audible as cleaner SSB!!
Alternative CW crystal filter:
JRC's narrow CW crystal filters are very hard to get nowadays and are too expensive.
Kenwood has equivalent 250 Hz - 455kHz filters, in the same footprint type YG-455CN-1, also from the NDK factory.
They won't work because the wrong impedance and a DC short circuit to ground.
But with two minor impedance transfer and DC separation toroids it will work,
even better than the original JRC 300Hz CW-filter, which has a VERY bad shape factor ( above 4) !! See further down.......
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The toroids you see are 3E25 - 14mm - AL=2200
It transfers the 600 Ohm to 2000 Ohms and back.
It also gives the needed DC separation.
Windings are 20 for 600 side and 36 for 2000 side.
So it's about 1 to 1.826 in N, and 1 to 3.333 in Z.
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CW FILTER COMPARE.....
(A very bad shape)
The small curves left and right can be enlarged.
The RED curve on both is the 600 Hz KOKUSAI.
You see the curve shape of both filters
on two filterboard's.
The smaller GREEN curve left is the perfect
KENWOOD narrow CW filter.
At right you see the (GREEN) JRC CW filter curve.
It is rather straddle legged and JRC should have
ordered a better filter at the NDK factory.
Shame!
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If time permits I will place a link here how to measure those filters and how to make additional buffer amplifiers
to connect it to a Selective Level Meter setup.
( Wandel und Goltermann !)
Here you see a quick preview of the setup.
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Kokusai Filter Repair:
Kokusai Mechanical filters have a habit of deteriorating in time due to decomposing of the foam inside it.
It becomes a sticky gummy mess, which dampens the vibrations of the resonating disks.
With extreme care the shit can be dissolved with nail polish remover (in Dutch: aceton) or even better with isopropyl alcohol
and repaired with fresh foam. After some experience: packing foam works better than cotton wool!!
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Before the cleaning
Picture © by Luuk
Radiohobby
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John Kolb ( KK6IL ) is a Kokusai Mechanical filter specialist and has a special site about it....
Go to John and read it over there in his own words.
John's site is NOT available all the time.....
Due to public demand I've made a backup copy over here. Sorry in advance!
The pictures you see over here are from a radio friend: Luuk. He also managed to repair it too.
All the pictures © from Luuk in one small PDF sheet.
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After the cleaning
Picture © by Luuk
Radiohobby
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Before the cleaning
Picture © by PE1ABR |
After a whole series of cleaning actions a friend of mine (PD0SDQ - Peter) developed an even better method of restoration. NO cotton wool, as I did like John, but packing foam.
Almost the same as on the pictures from Luuk. But square stiffer foam blocks with a hole in it over the piezo units, that is used at the ends to position the disks only, no pressure on the disks themselves. On top and underneath only a thin sheet of foam to fill-up.
Indeed it works just a bit better, lesser damping of the resonating disks!
Here you see what should be trick!!
One filter is a 2.4 kHz version, the other is a 600 Hz version. Do you notice the differences in disk numbers and the size of them??
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After the cleaning
Picture © by PE1ABR |
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Frequency calibration:
Blown uPB426 chip on the synth board ??
This chip is the band segment decoding table out of the frequency range
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Click to go to the page with PDF hardware information and
how to build your own decoding chip with a GAL22V10!!
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VLF ADDON, extension down to 10kHz:
More modifications are needed to the input circuits to work properly
VLF mixer add-on (the extended version drawing)
VLF modification simple (overview sketch)
Excellent reception from about 25 kHz
Only exchange some capacitors and two resistor like inductors
VLF modification extended (overview sketch)
Only do this if you are experienced, also a relay is added and
an extra input toroid in the first mixer to extend the Rx range
to as low as 10 kHz without degradation of sensitivity
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PHOTOGRAPHS section:
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Photographs from the NDH-518 memory unit
with eprom BIN-BCD address decoder,
push-button and rotary-opto up-down control
Click here or on picture for sub-page
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Photographs from the NDH-515 memory unit
with two GAL's for BIN-BCD decoding.
Only one hole for extra bankswitch needed
Click here or on picture for sub-page
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Photographs from the NDH-518 memory unit
with two GAL's and remote control options.
Most complex version
Click here or on picture for sub-page
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The design of a set of replacement uPD5101
modules for an exploded memorybank
NEW
In DUTCH and ENGLISH available
Click here or on picture for sub-page
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Photographs from the NWG-515 Remote VFO
A NWG-515 ?!?, a very peculiar thing.
Click here or on picture for sub-page
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Mains-inlet changes
Safety modifications mains filter to comply with new regulations
IEC power input exchange with real mains-inlet filter.
Click here or on picture for sub-page
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Click over HERE for a direct hop over to all the other radio information on the next page.
If you do not have the "Acrobat Reader",
please access to the site of Adobe Systems Incorporated.
The Acrobat Reader is distributed by Adobe
Systems Incorporated free of charge.
Adobe, Acrobat Reader, and their logo marks are registered
trademarks of Adobe Systems Incorporated.
A nice NRD-515 YouTube video I found, a perfect place over here to embed it.
And there is a lot more to see...
Copyright© 2001 - 2011 Walter Geeraert - All Rights Reserved
index515.htm
by Walter - PE1ABR - 2011-10-21
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