Another VHF aerial question ...

PuffTheMagicDragon

PuffTheMagicDragon

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I have an old Icom Hand-held that I cannot use any more as a H/H because the batteries won't charge (and the only supplier that I found will not mail replacement battery packs out of the UK /forums/images/graemlins/frown.gif).

My question is this: Can I use the little flexible aerial that is on it (marked FA-104BF) as an emergency aerial to be used with the fixed VHF set?

All it would need - if it works - would be a length of cable with a PL259 at one end and a male BNC at the aerial. Fishing rod can be used for hoisting in case of loss of rigging.

Any opinions anyone? Not too technical please because, where electronics are concerned, I am of the 'black-magical-box-that-does-what-I-want' variety of user. /forums/images/graemlins/wink.gif

Thanks.
 
There are companies out there who will break open a battery pack and put repalcement cells in for you all very neatly, this may allow you to continue use of the HH is you so wish. I can't comment on the use as back up aeriel.
 
Buy rechargeable batts and solder them in, should be available most places. They may be less efficient (and check whether NiMH etc) but they'll be cheaper. It should be straightforward DIY. Keep and eye on the heat generated when re-charging though in case charger/batt not properly compatible.
 
Which radio is it... I bought an AA cell pack for mine a few years back after John Brooks contacted me on here, if it is an IC-M12 then it is the same unit as mine, he did say at the time (circa 2004) there were only a few left. I think it was around £14.00 or so, I would have to dig out the receipt.

On the other hand, I have also been into the nicad pack (nicely screwed together not glued like laptop batteries), the cells are easy to get and even easier to replace, there is very little to it.

Things like this are why I buy and recommend icom for h/h radio telephones, the support is still there for me on a radio that is approaching 19 years old.

<span class="small">*usual disclaimers apply, but I will say more nice things about icom if they send me some diodes for the matrix board /forums/images/graemlins/grin.gif</span>
 
[ QUOTE ]
My question is this: Can I use the little flexible aerial that is on it (marked FA-104BF) as an emergency aerial to be used with the fixed VHF set?

All it would need - if it works - would be a length of cable with a PL259 at one end and a male BNC at the aerial. Fishing rod can be used for hoisting in case of loss of rigging.

[/ QUOTE ]

I don't know what that aerial is specifically, but if my opinion's worth anything after the DSC alert debacle, I think it would work but wouldn't be as good as a longer aerial.

Can't help feeling that sorting the HH out would be much more use, though - you've then got a spare VHF, battery and aerial, and you can take it with you if you have to leave.

Andy
 
Please could you explain why matching, SWR, etc. will be bad? (Always thought 50 ohm was 50 ohm, at least until you start getting sparks ??)

Andy
 
The individual cells seem to be 29mm long (approx. I haven't taken them apart) whereas the commonly available AA are more like 50mm long. The diameters are also different; so I don't really know which size to look for.
 
The set is an old IC-P2ET. There used to be a 'battery case' (BP-110) which would have been ideal as it took plain AA cells but it is no longer available; at least, I have not been able to source one. I did find a battery pack that would fit, the BP-113, advertised as a clearance item. This too would have been a good solution as it has a bigger capacity.
Unfortunately, the company told me that they will not ship out of the UK 'because postage costs would be exorbitant' (sic.). It wasn't exactly cheap either - £35 - when one considers the advertised prices of complete hand-helds!

Thanks for your interest.
 
Probably yes

Reasonable assumption that its 50 ohms

Difficult to say how to mount it, perhaps best use some insulating material to make a bracket. Fix a suitable connector to the insulated bracket and coax connected to the socket.

Using a fixed set there will be an earth connection at the set. best to avoid having an earth connection at both ends of the coax.

Impedance not affected by the power, and 25W isn't going to make it burst into flames.
 
Providing that the coax connection is sound, the ariel could be used as a back-up without undue concern. It's already tuned to resonate within the marine band vhf band so it's impedence will be correct. There are three issues to consider. 1. Losses through length of cable, joints and non-tuned length; all likely to impact the vSWR. 2. Hight of emission. 3. Poor gain from a compromised design that focuses on size, not efficiency.

Looks like you'll follow the route of getting the battery replaced so this is laregly academic now.

David (had an amateur radio licence since 1981 and long since forgotten 99.9% of the theory!).
 
I had this problem with one of my amateur radio hand-held some years ago (Trio 2500 and Trio 3500). The battery that was required was an F-type and it looked like a short AA battery but slightly larger diameter.

If these are the correct type, they are available from a number of sources (Maplin etc) just Google it!
 
Thanks for the tip. I shall certainly look up the dimensions of the F size; however, I do not think that the diameter of the cells that I have could be much greater than that of an AA. One way of finding out ... /forums/images/graemlins/wink.gif

I also noticed that there are some components stuck in the space between the individual cells. I suspect that they could be some zener diode and / or something to limit the current while being charged? Here again, I'll know for sure if I have to take it apart - although it always helps to know what to expect.

Thank you for your input.
 
The AA battery size is 50½mm x 14½mm. There is a possibility that the battery you require is the 2/3AF Battery which is also available from Maplin. Its size is 29mm x 17mm. Its Maplin code is VN40T See:

http://www.maplin.co.uk/Module.aspx?Modu...ry&doy=18m7

Regarding the components tucked between the battery pack, these are thermal limiting devise which controls the charging. When you rebuild the battery pack they are fairly easy to fit into place.

Where are you in the world?
 
Length is approximately 28mm while the diameter is closer to 14mm. Definitely not 17 though. I do not have my callipers handy at this time.

I am in Malta.
 
Please could you explain why matching, SWR, etc. will be bad? (Always thought 50 ohm was 50 ohm, at least until you start getting sparks ??)

**********************************************

It is......Power does not affect match. The antenna connection on a hand held is 50 ohm...after all we buy adaptors to connect out masthead antenna to our hand helds so there is no reason why you can not do as planned.
 
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