Author Topic: Italian "Fava" field phone  (Read 845 times)

Offline countryman

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Italian "Fava" field phone
« on: December 05, 2020, 05:44:54 AM »
I generally do not collect field phones. I will make an exception for this elegant one that reached me from Milan/Italy, known as the capital of the leather fashion.
In fact the case is only synthetic, but I believe earlier ones might have been real leather? Any Italian Signal Corps officer will look really neat with it, however.
The phone has a dial and on the seller's pics there was no crank visible so that I mistook it for a lineman's test set. But it has a magneto and the metal switch on top is a selector for CB or LB operation. It has a third (momentary) position for ground signal.
I can dial out and receive with the phone but it does not transmit. The wiring of the battery has been screwed up. The battery leaked out and made a mess and that might have something to do with it. I cleaned up the rust so far and the springs are still intact. I hope to get it going again. The transmitter capsule tested good in a different phone.
I can't find anything on the web about the manufacturer "Fava" or the phone itself. A wiring diagram would be helpful right now.

Offline Key2871

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Re: Italian "Fava" field phone
« Reply #1 on: December 05, 2020, 06:16:18 AM »
Well for having a battery leak, it looks pretty nice. And I agree that's a nice set to hold onto.
Good luck with your repairs that is a real nice piece.
KEN

Offline dsk

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Re: Italian "Fava" field phone
« Reply #2 on: December 05, 2020, 12:04:12 PM »
If you know someone who may speak/write Italian you may get help to ask the company (looks like they will understand English too  :)   ). https://fava-ivo.com/en/product-category/telephony/   

Nice phone, I guess you get it alive if you just solder on a contact set for a suitable battery. What battery was the original?

Offline countryman

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Re: Italian "Fava" field phone
« Reply #3 on: December 05, 2020, 12:35:02 PM »
Thanks dsk. The contacts are all there. I guess the microphone battery was 1 D-cell. In addition, there is a clip and a holder for a 9V battery, unusual and irritating?
The wires were taken off the contacts of the D-cell. I guess I will use the try and error method... the wiring is no rocket science. A diagram would be nice though, and usually field phones have one permanently imprinted, but this one not.
Thanks for the company link! They even still make a LB set. I guess I might write them in German as the location is in South Tyrol, the northernmost and bilingual part of Italy near Bozen/Bolzano in the Alps, right adjacent to the ancient language boundary.
The address is Via Meucci (Meucci street), how appropriate!
« Last Edit: December 05, 2020, 12:40:45 PM by countryman »

Offline countryman

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Re: Italian "Fava" field phone
« Reply #4 on: December 13, 2020, 09:33:17 AM »
I kindly wrote the company in German and also google translated it to Italian. I used their Facebook site to keep it informal, but got no answer so far. Maybe it was too informal. Or I should have written that I am the army of (add any country name) and want to order 1000 pcs.?  8)
The wiring is no rocket science for sure, but confusing. Some wires were soldered wrong but I eventually figured that out. The transmitter tested good in a CB phone but... you guessed it already... with only 1.5 Volt battery voltage it won't work well. Maybe it's aged, maybe just the wrong (CB) transmitter element that came with it.
I finally fitted a brown AKG DKO48 element (transistor mic for German field and railway LB phones). This works fair, but is originally made for 3 Volt. I measured a mic current of 2.5 milliamps, which is still low.
I might try and build a transistor mic that copes with this low voltage. Nice project for the holidays/shutdown time we are facing. Otherwise I'll modify the battery holder for 2 AA or C cells.
The 9V battery adds this voltage to the outgoing line in LB mode. That way any CB phone can be connected and communicate with this field phone . An interesting feature!
« Last Edit: December 13, 2020, 11:10:39 AM by countryman »

Offline dsk

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Re: Italian "Fava" field phone
« Reply #5 on: December 13, 2020, 11:12:26 AM »
If you need the battery in both CB and LB mode, I would have stored the hard to get brown AKG DKO48 transmitter for another project. In this phone a 9V battery will fit well, and then you could use a real CB transmitter there.  If the current will be to big, just add a resistor in series.
dsk

Offline countryman

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Re: Italian "Fava" field phone
« Reply #6 on: December 13, 2020, 11:31:14 AM »
The microphone is on the 1.5 V cell all the time and the phone won't work without one. The 9 V battery is for the operation of a CB extension phone only.
« Last Edit: December 13, 2020, 11:37:19 AM by countryman »

Offline countryman

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Re: Italian "Fava" field phone
« Reply #7 on: December 25, 2020, 10:55:34 AM »
The same seller now has this unit on eBay - a "portable telephone and line tester" made by URMET in Torino. It seems to have some functions similar to my Fava set, LB / CB operation and an additional battery for test purposes or the operation with a second CB phone on a stand-alone basis.
So my earlier suspicion that it is not a field phone may have been correct.
Both sets, the wooden box and my plastic/imitation leather version also just aren't heavy and rugged enough to be typical military equipment.

Offline countryman

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Re: Italian "Fava" test set
« Reply #8 on: January 11, 2021, 04:29:21 PM »
I now did an attempt to draft a diagram of the "telefono di prova Fava" from the original post. The ribbon cable wiring looks simple, but the wires change their colors inside a connector, very confusing!

It becomes obvious that this is NO field phone, but a dedicated lineman's test set. It acts as a CB phone plus magneto all the time, with the option to feed 9 Volt DC into the line. This way a lineman can call and talk to a coworker or even a subscriber using an identical set or a normal CB extension. Is there any other test instrument with this option?

They are available used: https://radiosurplus.biz/strumenti/usata-revisionata/test-di-misura/telefono-di-prova-fava/
« Last Edit: January 11, 2021, 04:54:08 PM by countryman »

Offline dsk

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Re: Italian "Fava" field phone
« Reply #9 on: January 12, 2021, 04:39:38 AM »
Great!
When you mentioned that the but set used by the Norwegian "Televerket" in the 70'ies and 80'ies was called the banana among those who used it.  It had a 22.5V battery in series as an option. 
The quality of your phone is obviously much better  :)

I wrote a little about it here: http://www.classicrotaryphones.com/forum/index.php?topic=24740.new#new

dsk

Offline countryman

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Re: Italian "Fava" field phone
« Reply #10 on: January 12, 2021, 07:20:47 AM »
Not sure if the quality is better, but the batteries are easier to obtain :-)
22.5 V is an oddball today. But probably the higher voltage allows a longer line.

I fabricated a makeshift crank, because the original one was missing. Not overly fancy but it works. The set comes in handy to check if a phone rings, transmits and receives.