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-518.
Has only 256 - 4 bit locations!
Very hard to get for repair because due to it's 256 locations it has become rather useless.

2101   National


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


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 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.

Now available through ALI from China. Only give uPD5101 as search text, not more. It is a Dutch/ NL link.

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

For the "struck by lightning" version!

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
HB1 relay
NR-HD relay
HB1E-DC12V used all through the NRD-515.
Not only used in the attenuator circuit, also in VFO-control (INT - EXT).

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 ALI in China. DO NOT buy the cheapest, there is a lot of unfunctional scrap available!


More standard Toshiba audio amp used in later JRC equipment.

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

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 a tiny heatsink?


Old 256 step R-array D/A converter.
Used in my 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 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 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 hopeless damage case, a 515 being struck by lightning, and 25 chips blown......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
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.

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.
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.

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

Recently sent to me:
MI301, the input protection PIN diode (bad scan).
MI303, a version that is compatible.

I personally also used standard BC-band/SW switch (PIN) diodes like BA243. Use more of them (double in number) in series.
They are much less rugged, but will work as protection if you have nothing else!
If you only cut them without adding a static bleeder (1K to 4K7), C15 (100nF) will fail.
You can add this R anyway


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.




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.

Also a simple self made PDF for the SN16913P.


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.

"Not found yet"

LR3671D - magnetic encoder interface chip NRD-535 and NRD-525
CX7925B - PLL chip NRD-535
SN16913P - Another mixer circuit
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 - 2016-08-17