comm radio wattage

[Walt]

Reading is a lost art

[BobTurner]

Originally Posted by Walt

in case you are interested in doing so, the cost would be a poultry $4995

Well, I think I can read, if I take my time.
"paltry" has to do with a small amount
"poultry" has to do with a chicken. -

[Paul 5r4]

Thanks guys! $4995.... WOW I'll pass. I didn't see the 28V requirement either.

[Walt]

Originally Posted by BobTurner

Well, I think I can read, if I take my time.
"paltry" has to do with a small amount
"poultry" has to do with a chicken. -

Never said I could spell
(can I blame spell checker?)

[Walt]

Originally Posted by Paul 5r4

Thanks guys! $4995.... WOW I'll pass. I didn't see the 28V requirement either.

Once again, there is NO 28V requirement...

[jliltd]

More is not necessarily better. Keep in mind that a 16W transmit capability means your coax and connectors had best be the good stuff and in perfect shape. Same for your antenna placement and good ground plane bonding. A set up that works perfect at 10W may get taxed at 16W due to this stuff. Not to mention #2 comm having to shield itself from the transmit interference strength of a 16W #1. So maximum distance from all other antennas and electronics become more critical which can be difficult on a small airframe. Lastly, a higher transmitting power requires more amperage from the bus. That can be a bigger whack to the system and wiring. So battery and charging system need to be maintained to a higher standard. Other avionics may more easily exposed to undervoltage in their sensitive circuits. This is one of the reasons designers prefer 28v over 14v when it comes to high wattage aircraft transmitters.

I say there is a reason most tramsmitters we use in small aicraft are 6 to 10 Watts. Experience has shown they work good, are forgiving of instalation issues and don't cause much trouble.

Jim

[dlloyd3]

The Trigg remote radio has a 6W output. This is the radio Dynon uses for their comm and PS Engineering uses with their PAR200 (# ?) audio panel/com. Haven't heard any complaints about weak output when properly installed.

[Bill Boyd]

By tradition (and the IARU) an "S-9" signal on VHF is supposed to represent 5mV of signal across an input impedance of 50 ohms. This equates to a field intensity of -73dBm.

More to the point of this discussion, an S-unit is supposed to represent a 6dB difference in signal strength. The ratio between 10 and 16 watts of output power is 2.0 dB, or 1/3 of a standard S-unit. Based on 40 years of radio experience, I suggest no one can reliably hear the difference in the two, Flight lever 180 or not. Your finals will feel the difference because it's 60% more heat to dissipate.

To me it would make more sense to restrict rather than increase TX output power at the higher flight levels to avoid same-channel interference. Elevations of 3-10 miles don't add appreciably to the slant-range-to-target when communicating with a ground station at the horizon. Nevertheless, I don't make the rules - I just question them

[622BH]

I have two GTN-650s installed in my 9. At 3500' I am communicating beyond 80 miles. That should be more than enough on any IFR flight.
Increase altitude results in an increase in comm range - to a point.

As mentioned previously: the new GTN 650s can utilize the 16 Watt option IF you purchase the requisite enabling card; which is bloody expensive.

[BobTurner]

Originally Posted by Bill Boyd

By tradition (and the IARU) an "S-9" signal on VHF is supposed to represent 5mV of signal across an input impedance of 50 ohms.

I think that?s 5 microvolts, not mV (millivolts).