Powering Up With No Bridge Antenna

[the_doc]

There were some posts in the past advising not to power up without an antenna as to do so may damage the bridge.

If the GPS dongle and DVB dongle are removed, and the unit powered up with no bridge antenna connected, is this still the case?   Or would the bridge be safeguarded as there is no GPS information and so it will not transmit or receive?

If it still is a problem and danger to the bridge, have the team thought of producing a little gadget to screw onto the bridge antenna connector that produces the same impedance/resistance and protects it for when people bring their units home having left antennas in the aircraft?

[Admin]

There were some posts in the past advising not to power up without an antenna as to do so may damage the bridge.

If the GPS dongle and DVB dongle are removed, and the unit powered up with no bridge antenna connected, is this still the case?   Or would the bridge be safeguarded as there is no GPS information and so it will not transmit or receive?

Potentially, but I would not rely on this TBH

If it still is a problem and danger to the bridge, have the team thought of producing a little gadget to screw onto the bridge antenna connector that produces the same impedance/resistance and protects it for when people bring their units home having left antennas in the aircraft?

No need, you can buy these already, just search for 50ohm SMA termination

quick search found this
http://www.ebay.co.uk/itm/SMA-Male-Cable-Terminator-50-OHM-Coaxial-Termination-Pack-of-2-F95855K-/231727263845?hash=item35f4057065:g:P70AAOSwT5tWJ2Cp

Thx
Lee

[the_doc]

That's fantastic Lee.

Thanks so much. I'll order a couple.

[Ian Melville]

You may get away with those for low power transmissions. They are not intended to be stuck on a RF power transmitter and may get hot. Proper dummy loads have a power rating. I have 60W finned one at home from my 78MHZ Radio days, but that would be overkill, one of these would be better. If it would was me I would seek out a 1 or 2W version, make sure the gender is correct
http://www.ebay.co.uk/itm/1pcs-SMA-Plug-RF-Coaxial-Termination-Dummy-Loads-1-2-W-0-5-watt-DC-2-5GHz-50-Ohm/322065885392?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D40812%26meid%3Dbb408da81fea4ffc889641d0b987f24a%26pid%3D100005%26rk%3D4%26rkt%3D6%26sd%3D232196817992

Other dealers are available

[the_doc]

B*gg*r!  I already ordered Lee's suggestion.

Are we saying that the one I have ordered is not adequate?  How does this work?  Am I right in thinking that it is in effect a resistor designed to disappate energy from the transmitter, so the higher the wattage quoted the safer the transmitter is?

[Ian Melville]

I've not opened one up, but yes I think they are wire wound resistors. As the power rating is not specified on the one you have ordered, I have no idea if it is adequate or not.

The PAW is not transmitting all the time so you may get away with the one ordered. For the cost of a few quid, I wouldn't risk it if you plan to use it long term. However if you are just doing a few tests, see if it does get warm, and make a mental note of the temp. If it changes much, either getting cold. or hotter, then stop using it.

You could always return it for the cost of postage?

[Admin]

I think these will be fine, I recall the transmit is appox 6ms in every 1.8 seconds at 500mw

Thx
Lee

[the_doc]

Can it do any damage putting one with a higher power rating on?

Pity they're not in the PilotAware Hardware store, I'd be far less paranoid about whether I was using the correct spec device!! 

[Ian Melville]

No damage.

The whole idea of PAW is to enable you to see and be seen, why on earth would the PAW team encourage people to turn off the very thing that they paid good money for?

If you only want an ADSB receiver then there are other systems available. As you already have the hardware they won't cost you a penny. What is it about PAW that makes it compelling to you?

[the_doc]

Don't worry Ian, I'm not losing my marbles!!!

I asked the question as I simply want to turn the unit on to connect and download my track logs, and periodically update it at home. Problem is, I tend to forget the aerials and leave these in the aircraft. I thought because the GPS dongle and DVB dongle would not be connected that this alone would do the job of preventing the bridge being used to transmit, but like Lee says realise it's probably best to go for a belts and braces approach!

I've created a prototype remote aerial holder that I will release pictures of in due course and if there is demand see if I can get batch produced for people. Problem is it works so well, I keep leaving it in situ!

Lee- is it a possibility to have the software disregard and "ignore" the bridge altogether if the GPS and/or DVB dongles are not present?  The logic would be that if someone has the unit in that state, they either have serious hardware failures or they are at home upgrading/downloading tracks, and shutting the bridge off totally would therefore protect it?

[Ian Melville]

Fairy nuff. You have a perfectly reasonable reason.

Any spare 2.4ghz antenna would be good enough to to screw on.

The problem with by our last suggestion is there is a possibility that a user may leave the dongles in?

[Admin]

Lee- is it a possibility to have the software disregard and "ignore" the bridge altogether if the GPS and/or DVB dongles are not present?  The logic would be that if someone has the unit in that state, they either have serious hardware failures or they are at home upgrading/downloading tracks, and shutting the bridge off totally would therefore protect it?

This is actually how it works right now.
If there is no GPS fix, it is not going to try and tranmit your data.
I personally would not power the unit up without either an antenna or dummy load attached
During the boot up sequence there is no guarantee what the OS is doing to its IO during self checks

Thx
Lee

[the_doc]

Thanks, all understood.