Making contact by FM radio

[grumpy old man]

what about morse code?
any idea's about setting one up like the old days

[Skean Dhude]

Grumpy,

Morse code is still very popular today and many radios have an attachment to allow the operator to use it. It has several advantages a such as range and noise is less of an issue but it needs training. There is some information on the main site about this including training packages.

[Brian]

What about using marine band radios for contact comms? These sets are cheap(ish) are readily available and have pre-set channels for various uses including the emergency distress channel 16. Sets can be picked-up on ebay for a few quid and run off a 12v battery, other sets are hand-held and are rechargeable but some do take alkaline batteries. Depending on radio type and aerial arrangement and location ranges of 50 miles are not uncommon.

[Skean Dhude]

(14 September 2011, 16:47)Brian Wrote: What about using marine band radios for contact comms?

A viable option for us all. I'm trying to find out a bit more about the differences between all the different radio types.

[Reality Jones]

(14 September 2011, 09:27)Skean Dhude Wrote: Radios don't need that much power but transmitters do require a lot more than receivers.

Is there a minimum size for the FM transmitter to be to make it effective over long distances? Anything over a certain size is gloing to make it difficult to hide and as we all know, the less obvious we are the better chance we have of being overlooked by the crowd.
RJ

[Skean Dhude]

I don't know the answer to the minimum size question. Although experience shows that even powerful radios are smaller than show boxes. Not very big at all.

The antenna though is the biggest issue. To receive requires a bit of wire but to transmit requires a larger, usual a quarter or half of the wavelength which can be dozens of metres. This is not so easy to hide although it can be done.

[Skvez]

The Size of transmitter (the physical box) shouldn't be an issue for a fixed location.
As Skean stated the Size of the aerial can be an issue, you get better distance with a taller aerial but you can conceal an aerial if you don't mind a loss of effective range.
The power of the transmitter directly affects the volume you can cover with the transmission. The standard 4W CB will get you over 10 miles (in today's noisy environment) some commercial FM radio stations are pushing thousands of Watts.

To be "the Village Vigil Voice" you probably only need a 100mW transmitter.
The Original Post was about getting/making a small transmitter that could transmit on the standard FM band so that others in the neighbourhood could be informed of looters/raiders natural disaster risks in the area.
I see little point in being able to transmit on a HAM radio when nearly no-one else out there has a HAM radio to listen to you.

[Brian]

I agree with Skvez, the common shelf radio is all most people will have and FM is the most commonly listened to frequency. VHF might be a close second as all PMR's, marine and aviation use this frequency.
Brian

[grumpy old man]

ariels can go side ways from post to post aswell

[Skean Dhude]

(17 September 2011, 23:57)grumpy old man Wrote: ariels can go side ways from post to post aswell

Good point. The US DoD have several large plots of land miles long set out with ULF radio aerials. We could easily do the same but make sure you have spare wires as any set up before an event would not survive an EMP