A very peculiar thing, a NWG-515.

This is a homebrew remote VFO ( WG = Me, PE1ABR) usable for all the old NRD Rx-Tx series.
It is largly a copy of the left half of the synthesiser drawing of the NRD-515.
The output frequency is 2.455 to 3.455 MHz in 100 Hz increments.
The tuning is also digital, like the NRD-515, with a selfmade opto unit, in a FISH tin can, made around a copy on film from a stroboscope disk. On the shaft is also some "dead weight" (visible as a red disk) to give it smooth tuning.
It is made as robust as the NRD-515 itself. Also the "casing". To be safe during the design stage, it is build and tested in smaller steps, to overcome failures if it is on a large board like in the NRD-515. The analog part is made in metal (brass) enclosed subsections.
It can also be used as a VFO for a homemade transmitter or other projects....

Click on pictures to enlarge,
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Keep also in mind that this unit is already more than 25 years old and never failed...... 		  © PROJECT ENGINEER:
WALTER - PE1ABR.


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A nice duo...., ready for split-Rx




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front,
delta f is with pushbutton.
Tuning the dial = auto switch-off!		 nwg515.jpg

back
nwg515.jpg

open bottom,

with 3rd mounting plate for extra's



 nwg515.jpg

open bottom,

extra units "door", a.o. FM and squelch unit and I/O buffers for MHz decade from Rx



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bottom plate bend sideways, visible now:
power supply part, analog signal part, MHz interface board, encapsulated transformer, fishcan opto unit.
In the NRD-515 the power supply dissipative (heatsink) zone was the back, here it was easier to use a side of the box.
nwg515.jpg

detail rotary unit, open fish-can with stroboscope disk on film and more power supply.



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Analog part opened

Now visible: 19 MHz oscillator, 38 MHz filter, 24 - 36 MHz VCO, mixer, divide by 10 part, more buffers and filters
The MC1350 has a heatsink !

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open top, digital part in sub units.
In the middle the crystal ref unit, at the bottom the display driver section.
The transformer has a VDR to absorb spikes and to protect the mains filter, a foil short circuit winding to suppress leak field and fits in an iron box. The mains cable wiring = SCREENED



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nwg515.htm
by Walter - PE1ABR - 2010-03-25