Making contact by FM radio

[Brian]

This looks a nice piece of kit but battery consumption at 4 watts output will be very heavy.
I use the Cobra MT600 set for airsoft using 1100 mAH batteries and even at the low 500 mw output I barely get 8 hrs standby with say 10% transmission time. This Intek unit uses 1500 mAH batteries but I'd be surprised if it would last more than 4 hours or so with 10% transmission time at 4 Watts. The answer is obviously lots of alkaline batteries or some serious recharging capacity. The Intek units use 5 AA batteries and with that consumption I'd expect each unit would need at least one spare set on hand, if not two - that's up to 30 batteries per 8 - 12 hours with only two radios in use! Wow! Also these MiMH batteries deteriorate with recharging frequency and progressively hold less charge, so short-term, low/occasional usage might be the best option but up to 20 miles range is becoming useful.

[NorthernRaider]

I noticed that one one forum the writer said he had fitted Nimh 2750 mAH batteries?

[Brian]

That would be a worthwhile investment for anyone choosing these sets. I know with the Cobra sets they can quite sensitive to the type of battery - even though Maplins say they can take alkaline in practice they don't. Apart from the expense of buying the 2750 mAH batteries, which could be pricey, the extra life would be a win - win. Charging would be the same issue though.

[Skvez]

2450 mAh is standard for a AA rechargable at the minute. 2750 is only 12% more

But we've drifted completely off topic.
The original thread was discussing the utility of contacting people without the need for them to have a special receiver.

[NorthernRaider]

(16 November 2011, 14:34)Skvez Wrote: 2450 mAh is standard for a AA rechargable at the minute. 2750 is only 12% more

But we've drifted completely off topic.
The original thread was discussing the utility of contacting people without the need for them to have a special receiver.

Dead letter drops, note boards and RZs are about the only option unless you can set up a courier service.

[Skvez]

(16 November 2011, 15:43)NorthernRaider Wrote: Dead letter drops, note boards and RZs are about the only option unless you can set up a courier service.

No, using a standard FM radio.

[NorthernRaider]

Going to need a heck of a powerful transmitter with an aerial over 200ft high

(16 November 2011, 17:09)Skvez Wrote:

(16 November 2011, 15:43)NorthernRaider Wrote: Dead letter drops, note boards and RZs are about the only option unless you can set up a courier service.

No, using a standard FM radio.

[Skvez]

(16 November 2011, 18:20)NorthernRaider Wrote: Going to need a heck of a powerful transmitter with an aerial over 200ft high

To do what?
To cover your local area (say your village) can be done with a 10W transmitter and a few meter aerial.
How do you think pirate radio stations managed to survive before triangulation?
Some of them still survive by driving the transmitter around in a van.

[NorthernRaider]

I see, so why do you want to broadcast to your village, the risk of being triangulated is very high, and prepper to prepper coms is usually better dont by PMR or CB broadcasts at a set time each day.

Mind you I'm dead keen to learn more for someone like yourself with more experience than me with radio comms.

[Skvez]

I have *some* experience with transmitters, I don't claim to have a lot.

Certainly the ideal scenario is that everyone you want to communicate with has the same (obscure) transceiver but realistically that's very unlikely outside your own small group.
My original question was asking what worth people saw in being able to contact others by a medium that almost all people already have.
What it could be used for (and whether this is worth the OPSEC risk) was supposed to be the point of this thread. I'd love to hear peoples' opinions of HAM radios on another thread but that wasn't the point of this one.
An FM broadcast over a small area could be used for
1] Warning of gangs or refugees entering the area
2] Voice of the Village - tell people how to collect water and other basic survival info without having to identify yourself and risk the locals overpowering you by numbers for your stuff. I'm sure there will be lots of discussion on this one as to whether we want the slightly-better-than-sheeple to survive a bit longer (prolonging their suffering) or just let them die quickly.

For contacting other groups if you have CB and they have Ham you're not going to be able to communicate but pretty much everyone will have a standard 88-108MHz FM receiver. You could even use this band to tell people where to find you on the more obscure bands.

Why do you (NR) think the risk of being triangulated while broadcasting over a small area is 'very high'? Most people don't know how to triangulate and the authorities/military and unlikely to pick up a weak localised transmission.