Dual comms

cvzyl · #1 04-07-2013, 12:59 AM

Hi

I am considering installing a second COM radio in my aircraft. Will I also need a second dedicated antennae for this radio or can both COM radios share the existing antennae?

I know this is probably a stupid question but I'm not very knowledgeable about avionics.

Regards
Cobus

roee · #2 04-07-2013, 01:18 AM

Cobus,

Welcome to VAF!

It is not a stupid question.

The long answer is, it is theoretically possible for two comm radios to share an antenna in certain configurations, but in reality there are many reasons why it is not practical. I can explain some of those reasons in greater detail if you're interested, but it would be purely an academic discussion.

The short practical answer is, yes, each comm radio needs to have its own antenna.

-Roee

alpinelakespilot2000 · #3 04-07-2013, 01:04 PM

Not sure if you intend IFR, but if not I would encourage you to consider just a radio that has dual monitoring. This allows you to actively listen and transmit on one frequency while also hearing what's on another frequency. Having just one radio is less expense and easier to wire. I'm VFR only and with my Icom A210 can't think of a reason why I would need a second radio, though I do have a handheld that I keep in the aircraft which can serve as a backup in a pinch. Good luck.

Mike S · #4 04-07-2013, 01:32 PM

Cobus, welcome to VAF

Good info above, just go with the dual antennas.

You might also need an audio panel, makes it easier to switch between radios, and many if not all of them allow you to monitor the second radio also.

BobTurner · #5 04-07-2013, 03:05 PM

Let's not complicate things too much. If you want an intercom then consider an audio panel. If you already have, or do not want, an intercom, then one or two switches are all you need to swap between radios.

cvzyl · #6 04-07-2013, 03:41 PM

Thanks for all the replies. I already have a radio, Garmin SL40, which is a great radio. Problem is I hate the Flightcom intercom. It opens all the mics when squelch is broken on one mic, which causes unnecessary noise ( 4 seater). It is also a pain to set the squelch as I don't necessarily use the same brand and model headsets. I want a PS Engineering audio panel for the AudioVox (automatically sets squelch for each individual mic and only opens the mic on which speech is detected). I have used PS Engineering intercoms in the past and love them.
During my search for the right model I noticed the PAR100EX which is a COM radio and intercom combined. I don't fly IFR and I know having a second radio is probably not necessary but I thought while I'm going through the exercise I might just as well get the radio with the audio panel.

Any thoughts?

roee · #7 04-07-2013, 05:05 PM

From your description of the problem that prompted all this, it sounds to me like all you really need is a better 4-place intercom. The rest is scope creep.

With a single radio, you don't even really need a full-blown audio panel. And being VFR only, and already having an SL-40 with standby frequency monitoring capability, it doesn't sound like you really have a need for a second radio either. It just came into the picture as "if I get A, then I may as well get B, and if I get B, then I may as well get C, and if I get C then I need D...". (A=better intercom, B=audio panel, C=second radio, D=second antenna)

So, to keep it simple and just solve the problem at hand, my general advice to you would be to look for a better 4-place intercom. I'm not familiar with specific makers or models to point you to, but unless you've exhausted that search already, that's the direction I would go.

And one specific avenue, since you've had good experience with PS Engineering products, find out what they have to offer on the intercom-only end of the spectrum. Mark Scheuer, CEO of PS Engineering, has been known to frequent this forum (username: mscheuer). Shoot him a message.

BobTurner · #8 04-07-2013, 05:16 PM

PAR100 is relatively new, so no data on long term use. However, PS has always made good products. Like the last post, I'd suggest:
1. Just get a ps intercom
2. If you want a second in the plane radio, the PAR100.
3. If you want an emergency (no electricity) radio, consider a PS intercom plus a battery powered handheld. (Transmit range will be limited but good enough for vfr use).

Btw, I agree, an intercom that opens all mikes when one person talks is going to have a lot of noise.

rleffler · #9 04-07-2013, 05:17 PM

One gotchas to keep in mind if you install a second radio, is minimum separation between the two antennas. Typically you'll want about 30-36", but use what is specified in the radio installation manual. You'll also want to understand how each radio handles transmit lock.

cvzyl · #10 04-07-2013, 11:56 PM

Thank you all for your replies. Roee, you are quite right, there is considerable scope creep. Maybe I'm looking for reasons to buy something I like but don't really need.

I'll contact Mark from PSE. I know they make quite a few intercoms but I'm not sure if any of them have built in IntelliVox.

Thanks again for all the input.

Cobus