hi all,

I seemed to remember that antenna should be fully extended when transmitting. Otherwise, final stage of TX circuit will be overdriven and finally burned. I am just wondering if this is still true with newer transmitter that has better circuitry design. I am asking because I use my transmitter with SIM interface and I hate to extend my TX antenna in front of my PC. My transmitter does not have TX on/off feature, but it just start transmitting as soon as I turn it on.

Any thought?
Thanks, Ckay

You should be able to take it out for a flight sim. Just for the future, I think it is transmitter not tranciever

Beat me too it Chad, saw the subject and thought... tranceiver in RC?


Trans(mitter) + (Re)ceiver = Transceiver

but I dunno about the actual question.

First of all, it's not duplex so it's a transmiter on one end (you on the ground) and the receiver on the other end (the plane).

The antenna is matched to the frequency of operation. the main reason to extend the transmitter antenna is, yes, to prevent the overload of the transmitter final circuitry.

BUTl in actual operation, with a plane in the air, the extension of both antennas is essential. Both antennas must be matched to the frequency of operation.. both the transmit and the receiver. So, fully extend both antennas for optimal operation and range.

dagnythepilot... I thought the very same thing while using it
on my AFP... I call Airtronics(my radio) and asked them, and
they said that it would be no problem???? But when I do use
it on the SIM, I remove my crystal, Which should eliminate
the transmitting????? And the battery really last a lot longer
also:-)

As Raideron said, if you remove the Tx crystal you can use it with the antenna collapsed (for flight simulation ONLY! )

When you remove the crystal the signal never reaches the final stage amp since you are removing the "bridge" that modulates the signal into the desired frequency

Cheers

Okay sorry, just a bad habit that I happened to deal with tranceivers. So corrention is TRANSMITTER.. :-)
I am using Futaba 8UAP. Does that mean that it is okay if I disconnect RF module from the body?

Thanks for all the help yo provided..

Ckay

Yes just remove the RF module on a module type Tx and no RF will be generated with no place to go.

Chad - having no aerial with the TX turned on is just as bad (if not worse) than not having it extended.

Removal of the crystal prevents the oscialltor from functioning thus the TX final amp has nothing to amplify and no damage will be done. For those who are interested the damage is caused since the final amp expects to see a certain impedence to minimise losses. The aerial only presents this load when it is fully exteneded. If it is not then it will cause an impedence mismatch which inturn causes reflections back down the aerial and into the final output transistor. Since the transistor is not designed to have power coming back at it, it will dissipate this energy as heat. After a while the transistor will heat up too much and fail. For the power outputs that we use this will take a while, where I work we deal with high power radio gear (50W) and have transmitters that will fail within microseconds if the antenna load is removed.

Hope all that makes sense

Cheers
Vaughan