VHF damage - transmitting without antenna

[CaptainHogwash]

Anyone know what type/cost of damage can be caused by pressing 'transmit' on a handheld vhf when the antenna is not attached? The kiddies found mine in a desk drawer recently (antenna unscrewed) and when I took it to sea the other day signal reception seemed really faint even with brand new batteries. It's an Icom M3 Euro in case that makes a difference. Thanks.

 

[PembrokeshirePromise]

I would have thought receive would still have been OK actually.
I thought that you burnt out the transmitter if you transmitted for more than a few seconds

Sure someone else will give you chapter and verse

 

[Boomshanka]

Depending on the kiddies' age(s)... check for playdough in the speaker grill - or any other socket /forums/images/graemlins/grin.gif

 

[ThereAndBack]

From the far back of my memory, I think it is only the output diodes which are at risk from tx without an antena.
No doubt, someone cleverer than me will be along soon with more detail or a contradiction.

 

[mikejames]

It will be OK

Handhelds will be designed to work with more mismatched aerials than fixed mount units. Leaving the aerial off or transmitting while it is lying down on metal and all other mistreatments inbetween will be expected.

Doing this with a cheap fixed mount set might be more fatal.

 

[matelot]

cant be absolutely sure that it applies in your case but most modern radio transmitters are designed so that they shut down before doing damage if you try to transmit without an aerial. in any case the damage would be to the power output stage of the transmitter not to the receiver. have you checked everything else that little fingers can get at? orange juice in the speaker? paydough in the mic?

do a radio check and see if the other party can hear you OK. then if that is OK make sure you keep your radio away from the rug rats in future
/forums/images/graemlins/grin.gif

 

[William_H]

Damage if at all will be total failure to transmit.
As said transmitters now often have a circuit to throttle back the transmitter in a mismatch situation.

However perhaps more telling is that in the early days of transistors it was difficult to get transistors that could cope with high voltage (an outcome of mismatch or no antenna) so they tended to be operated near to max voltage rating. Over the years higher voltage rating transistors have become cheaper so designers can be much or conservative or transmitters and more robust to this kind of abuse. olewill