Found one at the flea-swap real cheap. It is nothing like the 260, with a giant meter that emphasizes dB and Milliwatts.

I have a manual for it. Does anyone know what it's primary use was. I am guessing checking transmitter modulation for maintenance of commercial radio stations.

Based on the fact I can find music on only one AM station anymore:tears:

I am thinking of starting my own:D

It was basically a high sensitivity, large meter version of the 260. Because of these differences, it had a slow moving needle. But a good meter.

Thanks.
I could assume that the ohms-per-volt was not as high as a VTVM, but better than a standard 260.

As I recall, it was 100,000 Ohms per Volt, perhaps the highest ever for a d'Arsonval movement. That translates to a mere 10 microamperes to reach full scale, very sensitive.