Activating a radio by tuning fork?

[firedog359]

Hello all, I know this question is not Motorola specific but maybe someone can answer this. An ebay seller has a 1477 Hz tuning fork listed that he says was used on a railroad radio system to activate the radio to summon the dispatcher. He says you had to point the fork at the radio to turn it on. Is this for real or is he just totally misinformed?

[Bill_G]

Yep. That was the way it was done before you could make reliable equipment to generate a precision tone. But, just to be clear, you couldn't simply aim the tuning fork at the radio, and magically call the dispatcher. You had to key the radio, strike the fork, and then hold the fork near the mic for a few seconds. If successful, you heard an acknowledgement tone come back. Then you waited for a dispatcher to respond.

[jackhackett]

So this is kind of like a manual version of a vibrasender. Interesting.

[Bill_G]

Very much so. No installation required, and not affected by temperature. They didn't drift.

[firedog359]

Thanks so much for the information. It's amazing how things had to done in the good old days.

[Bill_G]

Old days? For some railroads, that's state of the art!

No. Not really, but they are loath to change much. They still use tones to call a dispatcher. But, the radios can spit them out with the push of a button now. Whether the dispatcher responds is still a coin toss. On the systems I work on, I have the console position generate the ack tone. If you got the tone, you just did a full comm check of the voice path - from your radio, over the air to the local tower, down the phone line to the dispatch city, through their equipment all the way to the dispatcher, and back. If you don't get a tone, something is broken.

[KitN1MCC]

i knew a few fire houses that still use that method

[fire_master_21]

Old days? For some railroads, that's state of the art!

No. Not really, but they are loath to change much. They still use tones to call a dispatcher. But, the radios can spit them out with the push of a button now. Whether the dispatcher responds is still a coin toss.

This is very much the truth! A couple weeks ago I went 120 miles before she ever asked who was calling.

[Bill_G]

Old days? For some railroads, that's state of the art!

No. Not really, but they are loath to change much. They still use tones to call a dispatcher. But, the radios can spit them out with the push of a button now. Whether the dispatcher responds is still a coin toss.

This is very much the truth! A couple weeks ago I went 120 miles before she ever asked who was calling.

(snort)