NONTUNABLE RECEIVER
Electro-metrics NTR-51C Nontunable Receiver
If you have never seen one of these before, You may be asking yourself " Who the heck needs a receiver that you CAN'T TUNE?? "
Well, before you write this off as another government boondoggle, just take a minute and FEAST YOUR EYES on this beauty.

HMMM...look at all those FILTERS...


Starting at the lower left end, you've got a bunch of LOW PASS filters.
They let you select the top end of your pass band, from 200 kHz to 1 GHz in a nice 1-2-5 sequence.

Now look at the next row above it.
It looks like the same thing, only HIGH PASS...
You could carve out almost any portion of the radio frequency spectrum, starting between 200 kHz and 500 MHz and ending between 200 kHz to 1 GHz. You can look at this chunk of the spectrum ALL AT ONCE, without having to diddle with tuning knobs and stuff..

And think of this: by doing it this way, your measurements will be very REPEATABLE.

Now, imagine what you could do with this thing once you get on the air. Specially if you have one of our ANTENNAS

If you want to play with one before you buy it, this can be arranged.

Now, GOING BACK TO THE PICTURE OF THE NTR-51C

On the lower Right end, we have "special filters.."
There are two extra HIGH PASS filters, a 5 kHz one and a 100 kHz one..

It looks like you could start your passband down at FIVE kHz instead of at TWO HUNDRED kHz.
Now, looking clockwise from the TOP LEFT, we've got:
*a handy little attenuator,
* some pre-and post amplifiers ( to reduce the interaction between the filters and clean up the signal)
* two adjustable high and low pass filters.

And hey, you could also end your passband at THIRTY MHz.
Now WHY WOULD ANYONE WANT TO DO THAT??
what is so special about 30 MHz? If you don't know, look it up or sign up for our ONE-DAY, ON-LINE, fully interactive E3 course