Tome Remote Meter

GEMOTO · Post by **GEMOTO** » Mon Dec 25, 2006 1:43 pm

HI Everyone,

I am looking for a DMM (Fluke) that has a dB scale to measure the line setting for a tone keying system i.e -16dB etc.

I was looking on the Fluke site and it looks like the 189 series have a dBm/dBV measurement setting but is there a less expensive model available?

I believe that when you set it to measure AC volts it should have a dB scale.

Thanks and Merry Christmas.

kcbooboo · Post by **kcbooboo** » Mon Dec 25, 2006 3:19 pm

I have a 189 and had a 187 before that. They both can display dB and using several different references. I have mine set for 600 ohms. You get four digits on either the ACV or ACMilliV range.

Depending on the line level you're trying to measure, the good old Simpson 260-series VOM has a dB scale on it, but you might want to run it through a capacitor to keep any DC out of the meter when measuring a phone line circuit.

I would think that some other meter models also can display dB, however it's not difficult to convert ACV to dBm, so if you do it often enough, make a conversion chart that shows you whole dB values for some common AC voltages. Save a lot of money that way too. 0 dBm at 600 ohms is 0.775V (roughly). 20dBm higher is 7.75V; 20dBm lower is 0.0775V. The rest can be calculated with common logarithms.

Bob M.

GEMOTO · Post by **GEMOTO** » Mon Dec 25, 2006 3:24 pm

Thanks Bob. I am looking for a Fluke. I am going to be using it for general purposes and to ocassionally measure the level of the gurard/status tones in voting/tone remote systems.

I looked at the Fluke meter comparison page and the only models that would display dB are the 187 and 189.

I was just wondering if any of their cheaper models are capabe of converting the AC volts to dBm for me.

kcbooboo · Post by **kcbooboo** » Mon Dec 25, 2006 3:44 pm

Well, here's one that's definitely cheaper:

http://www.elexp.com/tst_8229.htm

Looks similar to a Fluke. I just googled for

digital multi-meter db

and this one came up.

Bob M.

psapengineer · Post by **psapengineer** » Mon Dec 25, 2006 7:11 pm

Suggestion:

I'd purchase a used Fluke 8060a from E-Bay.

I've used mine for years in the two way / radio console / level setting applications.

I'd also consider purchasing a used HP 4935a test set to compliment it if your're going to be doing much level setting.....

Happy Holidays, Bob

Bruce1807 · Post by **Bruce1807** » Mon Dec 25, 2006 8:19 pm

The frequency meter on the 180 series is also usefull especially if your TRC units are over a long distance (going through amps at the phone company etc.) as I have seen frequency changes on the low level guard tone , enough to make the base drop out.

RFguy · Post by **RFguy** » Mon Dec 25, 2006 11:45 pm

The function/high level guard tones will be too fast to see it on a DVM. You may want to look at a scopemeter (search here for previous topics).
You can pick up a Fluke 123 scopemeter on Ebay at a good prce from time to time.

Bruce1807 · Post by **Bruce1807** » Wed Dec 27, 2006 6:31 am

True but you can read the level of the low lwvel guard tone as well as its frequency.
The flukes also have peak display so it can capture the initial HLGT level and display it without a problem.