SINAD Measurements
 

I just got a SINAD Meter at a flea market; as usual no manual.

It's a model 1410 by GAW Co., Inc.

If someone is familiar with the controls could you give a brief
description on the adjustment of the front-panel controls:

1. Tuning
2. Balance
3. What response should I get in the SINAD position?

I ask this question, because I get no meter indication what so ever;
probably why it was for sale.


//John

I just got a SINAD Meter at a flea market; as usual no manual.
If someone is familiar with the controls could you give a brief
description on the adjustment of the front-panel controls:
1. Tuning
2. Balance
3. What response should I get in the SINAD position?

A SINAD meter meters the difference between signal and noise
(gee, what a surprize).

Typically, these things have an audio input and a notch.
They measure the audio level before and after the notch.
The difference in levels between these two signals is the
signal to noise ratio or SINAD.

You use them with a RF signal generator to adjust receivers.
Modulate the signal generator with 1000Hz, 3kHz deviation
(did I mention SINAD is an FM thing?).

Assume that the 1000Hz signal is 20dB stronger than the background
noise. The complete signal has a level of X; the signal after the
notch has a level that will be 20 dB down (as it will only have
the background noise). The SINAD will be 20 dB.

Your box is adjustable; I suspect tuning sets the notch frequency,
balance sets the signal levels and SINAD is the signal level difference.

These are actually pretty useful devices if you want to squeeze
the last dB out of a receiver. If you don't have one, you can get by
by using a _good_ comms speaker and aim it directly at your ear,
then fiddle for minimal noise, reduce RF signal, fiddle receiver again, etc.
That's what I did before I got one and you can get reasonable close
this way too.

73,

Geert Jan PE1HZG

Many so called techs don't even know how to use them. You might find
out in a class. They are most used in verifying specifications. You
don't know how many experts have been unable to show me.

There should be no need for adjustment of the meter itself unless you
want to screw it up. If you don't know how to use it there won't be
an indication.

General instructions are available in Publication EIA/TIA-204-D

Jim, ac6tk

wrote in message
ups.com...
I just got a SINAD Meter at a flea market; as usual no manual.

It's a model 1410 by GAW Co., Inc.

If someone is familiar with the controls could you give a brief
description on the adjustment of the front-panel controls:

1. Tuning
2. Balance
3. What response should I get in the SINAD position?

I ask this question, because I get no meter indication what so
ever;
probably why it was for sale.


//John

"JB" wrote in message
...
Many so called techs don't even know how to use them. You might find
out in a class. They are most used in verifying specifications. You
don't know how many experts have been unable to show me.

There should be no need for adjustment of the meter itself unless you
want to screw it up. If you don't know how to use it there won't be
an indication.

General instructions are available in Publication EIA/TIA-204-D

Jim, ac6tk

wrote in message
ups.com...
I just got a SINAD Meter at a flea market; as usual no manual.

It's a model 1410 by GAW Co., Inc.



Unlike some of the "automatic" sinad meters such as the Helper sinadder the
1410 has to be adjusted by the user. Set the signal generator to a very
high output (enough to insusre a full dead quiting signal on a FM receiver)
.. Then crank in about 4 KC of deviation of a 1 khz tone (assuming a 5 kc
receiver) , The Tuning and Balance are adjusted for the best null, meter to
the left or 0 side. The signal generator is then lowered into the low
microvolt area tuil the meter reads -12 on the red scale if 12 dv is the
desired sinad point. You then read off the scale on the generator to find
the 12 db sinad point.