A collection of a few hardware PDF's.

Most of them are components used in the  JRC NRD-515  NRD-xxx series or in my own designs
Some easy found, some very hard to find, now all together over here!

Component code Information where used in the circuit

NEC version
Very old, very low power CMOS RAM, used in the NDH-515 / NDH-518.
Has only 256 - 4 bit locations!
Very hard to get for repair because due to it's 256 locations and dual I/O pins for data it has become rather useless.

It was available through AliExpress from China for some time, but not anymore.
BUT NOW: available as PCD5101 an old Signetics (Philips) version!

2101   National


HM-6551   Harris
HM-6551   Intersil
HM-6561   Harris
NMC6551   National

MCM5101   Motorola
MWS5101   Intersil
CDP1822   Intersil
NTE65101   NTE


Functional look alikes of the CMOS RAM above.

2101 is only suitable to test the circuit, it is NOT suitable for battery backup, it is NMOS and consumes so much energy your backup is empty within the hour.

The PCD5101, MCM5101, HM435101, S5101 (AMI), MWS5101, TC5501 and NTE65101 are identical. CMOS 4721B, MM74C920 and CDP1822 will probably work also.
The HM-6501, HM-6551, HM-6561, NMC6551 although, are a fully equivalent low power RAM for battery backup

Save and keep them if you find them in scrap.

The uPD5101 was available through AliExpress from China for some time, but not anymore.
If you want to try it once more: only give uPD5101 as search text, not more.
NOW: available as PCD5101 an old Signetics version!

PDF link
Diagram sketch of a replacement module for in an uPD5101 socket.

For the "struck by lightning" version!

uPD5101 is NOW available again through AliExpress in China.
Click on the small pictures to see a larger version how I made those modules.

Also take a look at the special
web-page about this module

In Dutch and English available!!
Memory upgrade MCM5101  uPD5101 Memory upgrade MCM5101  uPD5101

TC4036 / TC4039


Very old, rather unusual CMOS chip used as memory in the NRD-505 and NRD-66
Only four 8-bit channels

HB1/HB2 relay


NR-HD relay
HB1E-DC12V used all through the NRD-515 RF and attenuator circuits.
For VFO -control a double contact version is used (VFO INT - EXT), HB2E-DC12V.

NR-HD-5V is used in the NDH-518 memory unit.


Very hard to find audio output amp in NRD-515.
First I only had a Japanese PDF version, now a standard PDF from a second source.

I also got an equivalent circuit ECG1423 and cleaned the PDF.

Now available through AliExpress in China. DO NOT buy the cheapest, there is a lot of unfunctional scrap available I have experienced!


More standard Toshiba audio amp used in later JRC equipment.

Now available through AliExpress in China. DO NOT buy the cheapest, there is a lot of unfunctional scrap available I have experienced!

TA7140P  in Japanese

Audio buffer and pre-amp in NRD-515
Scanned from the same Japanese booklet.

And finaly I found the Toshiba datasheet, crippled FAX version, so I also cleaned it.



TA7045M is a high frequency (VHF) RF buffer amp used in the synth in the NRD-515. Very hard to get. It is used on 70 MHz as a buffer amp.

If a TA7045M cannot be found a CA3028 will also work. Not all CA30xx version are suitable for use at 70 MHz! The CA3053 is only suitable for 10.7 MHz IF. And a NTE724 will probably also work.


A Toshiba HF oscillator, mixer and Amp block, used in later JRC equipment.
The datasheet was a dirty version, I made a polished version out of it.


The MC1350 is an IF / RF buffer amp, also used in the synth, with less stringent requirements.
Used in front of the (adjustable) tune divider chain.

I've seen it break down for no apparent reason. Probably a thermal / heat problem,
add/glue a tiny heatsink?


Old 256 step R-array D/A converter.
Used in in my first version of the auto BC-tune circuit for the NRD-515.
Unfortunately no longer available........, see next item.

Analog Devices
Also an old 256 step R-array D/A converter.
Used in my second version auto BC-tune circuit for the NRD-515.
This D/A converter is still available, both IC's can be used!


Programmable bitmap array ( Bipolar TTL Prom ). Used to decode the input filter bank out of the display information.
If this device is blown you have "shot yourself in the foot"! You cannot buy it programmed, nor who will program it for you??
Solution, see next item.

NOT programming compatible, but equal in use after programming are f.i. Signetics 82S137, TI TBP24S41, Sharp IM56S26, Fujitsu MB7122, AMD 27S33, MMI 6353, National 74S573, Intel 3625, Fairchild 93415 or Harris HM-7643, and even others!

See PE1ABR's the TTL PROM list booklet for much more info.


Lattice datasheet

first set of files
to make the 22V10

second set of files
to make the 22V10

Manual sheet in PDF with information how to build the re-wire socket

A self-made solution for a blown uPB426 above.
For a hopelessly damaged case, a 515 memory / I/O cable being struck by lightning, and 25 chips connected to the MEM I/O port blown......(from Rx and memory), but it has been repaired!

With a double pin re-wire socket in between a GAL 22V10 will work if the uPB426 gets blown.
Smaller GAL's like the 16V8 and 20V8 have not enough product terms per macrocel.
Keep in mind: This GAL device has to be programmed too!
Put the *.JED file in your GAL-programmer. Tested and works great!

The first (early) version had a lot of don't cares, so I tried to make a better version. It was not easy possible to fit it in a smaller GAL ( 20V8 ), so the result is a different approach with a second version for a 22V10
It still could be possible with a 20V8 with fixed wiring for D3 and using its macrocel as a node. And a different re-wire socket. But the repair is already finished. It worked OK with a 22V10.

Click on the small pictures to see a larger version how I made those re-wire sockets.
Pictures are made by NL10194
Cor van Soelen - now PG9HF
uPB426 JRC NRD-515 uPB426 JRC NRD-515
NEW !! version

Original Motorola !!
This is NOT a standard CMOS circuit!
Very special phase frequency detector ( PLL ) originally made by Motorola.
Used in the synth circuit of the NRD-515 (and 505, and 525).
Very hard to get for repair from the original manufacturer. That's why it is new on the market by a second source: Agere Systems!

U310 FET
Siliconix - Calogic
Well known VHF FET used in the NRD-515 in balanced mixer configuration

U310 is the metal version, in plastic known as J310.

P8002 Power FET,
Texas Inst.
Well loved VHF power FET among radioamateurs, unfortunately almost NOT available. Used in my HF amplifier and first active aerial projects.
300% multiplied and highly cleaned PDF from PE1ABR.

2SK125 medium Power FET,
Also well loved VHF medium power FET among radioamateurs.
Used in mixers and HF pre-amp circuits. Can sometimes replace the P8000 FET if there is not too much dissipation.

2SK192A FET,
GR BL or Y

Well known tiny VHF FET used, or could be used, in the various JRC VFO modules















Some diodes used in the NRD-515 or their equivalents.

1SS315 as a replacement for 1S2187.
1SV149 as a replacement for 1SV100.
at last the real 1SV100 PDF.
1SV100 Cap-1Volt / Cap-10 Volt = ± 500 pF / ± 30 pF
1SV149 Cap-1Volt / Cap-10 Volt = ± 500 pF / ± 20 pF
BB212   Cap-1Volt / Cap-10 Volt = ± 450 pF / ± 25 pF

BB212 is a duo-version used in some BC-TUNE upgrade's.

The Fujitsu FC51M is a special high capacitance varicap, used in the 25 - 35 MHz VFO oscillator. Impossible to find a PDF.
I made a good working copy of this circuit for my remote VFO NWG-515. I used a just as hard to find varicap BB113, 3 high cap. diodes in one housing, I used 2.
It works great. See German BB113 PDF and VFO link.
BB113   Cap-1Volt / Cap-10 Volt = ± 250 pF / ± 75 pF
Some Chinese max capacitance (1 Volt) info: FC51M = ± 200 pF, FC52M = ± 105 pF, FC53M = ± 60 pF, FC63M = ± 380 pF, FC65M = ± 600 pF.

1S84 in the input filtering appears a Hitachi high voltage Ge diode, 200V - 4 mA
a 1N191 / 192 or 1N39 also works
In later JRC Rx's a 1SS85, VHF bandswitch diode, is used

MI301, the input protection PIN diode (bad scan).
MI301 = 80V 2A 5Watt UHF/VHF antennae switch PIN
MI303, a version that is compatible. Or use equivalent.
2x a 1N4004 in series for every single MI diode will also work
If seen this kind of "LF diode" being used in a Scanti receiver as protection (type = 10D05 from AEG).
Also a 1S920 is used, which is also a (fast) medium power rectifier.

If you only (unwise) cut the MI D's without adding a static bleeder (1K to 4K7), C15 (100nF) will fail. You can add this bleeder-R anyway

In newer Rx a 1SS149 is used. 200V - 150 mA. Same as MI301 above: "LF equiv." is BA157, BA158, BY204/4, BY206, BY207

I got a hint from Filip, use a CEL L407CD PIN diode, available at Mouser's. See PDF for datasheet.

Some special circuits used in the NRD-525 and NRD-535 in the power supply.

It is basically a tiny (SMD) voltage regulator without the power transistor.


A strange power supply IC (a.o. NRD-525), NOT the same, but in use comparable with the more common 723.
First 141 is in Japanese with all the packing variations, a.o. metal can and ceramic. Second is in English, with only the cheaper plastic DIL variations as uPC305.

uA723  Philips
LM723  National
LM723  SGS-Thomson
MC1723C  Motorola
Some variations of the well known 723
Old, but very universal voltage regulator
Used as an extra regulator for the VFO's in the 505 and 515.




Some special OpAmps used in the NRD-525 and NRD-535.

However...: M5218AL is compatibel with 1458 or 4558 and the M5237ML is compatibel with 358.

The above standard PDF's are (not so) coincidentally original JRC versions!


Texas Instruments

Two mixer circuits used not only in the NRD-525 and NRD-535, the SN76514 is even used in the Yeasu FRG7!! Found at last!
A pdf under a new component name ( TL442C ) - but exactly the same circuit.

Thanks to Hsu from China a scan from a Japanese TI-databook of the SN16913P.
At last a real datasheet!

The MC1496 is a special mixer / amplifier used in later JRC equipment.


A special synth/PLL circuit used in the JST series to generate the BFO signal.
I made a cleaned PDF, from a lesser quality version.
A newer second source ML145145 is available from Lansdale, but the PDF is badly made. The parts that are taken over from the old Motorola databook are scanned WRONG!!! They have scanned the documents in low resolution 16 million colors JPG (NEVER, NEVER do this!!) instead of high resolution 2 color TIFF.
And there are also versions on the internet with crippled fonts in it.


A special prescaler used in many synth circuits.



Replacement module

Opto encoder
LR3671D - (magnetic/opto) encoder interface chip in the NRD-535 and NRD-525
This is a special custom chip and NOWHERE available for repair. Once there was a replacement (PIC) CPU module available, but not anymore I'm afraid. It had a programmed PIC24FV16KA301 and a 74VHC126 I/O interface on it. See picture click.

As a bonus a PDF of the used opto encoder module connected to it.


Looking for complete Databooks?
Try the link, supported by Google.

Fujitsu varactor info

After decades of searching I finally did find some information to identify the Fujitsu FC-xxx range varactor diodes
I put the minimalist information in a text file.

simple sheet CX7925B

Sony complete

CX7925B - PLL chip NRD-535
After decades of searching I finally did found a Sony databook with PLL chip information.
So now not only a simple info sheet, but the complete original datasheet from Sony.

"Not found yet"

old FC-xx varicap datasheets
Old Toshiba databook to scan the old TA- and TC-xxxx stuff
The same could be said for old ROHM, SHARP LA-xxxx, FUJITSU MB-xxx stuff

Back to the NRD515 page

by Walter - PE1ABR - 2024-01-17