Comm Radio Box

[N74DV]

We're surrounded by several Class D fields so we have to have a radio on board. We've been using our Icom A-6 handheld with external antenna which does a great job but the wires and hassle have made us decide to add a somewhat more permanent installation.

We considered putting radio in the panel on the left side in the glove box area... but not wanting to have an avionics shop do it and make it legal we decided to go with a simpler and cheaper route.

A center console that acts as a self contained radio box. We'll mount it to the floor right in front of the bungees. Should be all legal since all it really is, is a large wooden cased handheld

Installed are:

MicroAir 720 comm radio
Sigtronics intercom
12 volt meter
12 volt NiMH battery pack
Solar charge regulator

We have an all weather solar panel that will be mounted with velcro to the top of the canvas cockpit cover to act as a charger to keep the battery topped off. The solar charge regulator monitors the pack and keeps it topped shutting off the power from the solar panel when the battery reaches 100%. Got the charge regulator on ebay for about $25. The solar panel was also purchased on ebay for about $60.

I also installed the optional 1/8" jack for an aux input such as an Ipod.

Tomorrow I try it out!

[cpirrmann]

Re: Comm Radio Box

Sweet! What are you doing for battery and charging? Also, what kind of antenna arrangement are you using?

[N74DV]

Re: Comm Radio Box

Sweet! What are you doing for battery and charging? Also, what kind of antenna arrangement are you using?

I have a fuselage mounted external antenna. It exits in the middle of the top of the plane right behind the wing.

Charging is handled via the solar panel as I described above.

I flew today for 1hr in the pattern. I hooked up my watt meter to monitor the amount of current draw the system has. I found that at rest, with everything turned on it draws about .190A. While transmitting it draws 1.4A.

After flying for one hour in the pattern with alot of radios usage talking to tower I consumed 212mah. So if I use a small 2400mah NiHM battery pack that should be good for nearly 10 hours of use.

The solar charger charges at 14v@ 20-100mah (depending on sunlight).... so essentially a trickle charge. With the regulator I'll be able to leave it parked out on the ramp for days or weeks and should keep the battery fressh and ready to go.

Tower said today that the radio was loud and clear... she said "in fact, I need to turn my headset down cause your radio is louder and clearer than the other planes in the pattern". So looks like the little MicroAir comm is a good little unit!

The Ipod feature worked flawlessly... muting the music when sending or receiving comm transmissions.

I'll get some pics of the box installed onto the floor soon.

[Richard Boyer]

Re: Comm Radio Box

Thats a pretty nice setup. If you used the XCom instead of the Microair, you wouldn't need the intercom as it is built in (and a cheaper radio). They use the same form factor.

[N74DV]

Re: Comm Radio Box

Thats a pretty nice setup.

Thanks,

the MicroAir does have an intercom but it is an always hot intercom and I also wanted the availability to plug in my Ipod.

It fits nicely in the plane and even though it's "portable" it looks very much like it should be there. We're happy with it

[Fred W]

Re: Comm Radio Box

That set-up looks great! Do you have shielded ignition? I've been using
an Icom A6 handheld clipped to the instrument panel but even at the
highest squelch setting, I'm getting lots of ignition noise. I'm going to try
putting ferrite chokes on the P-leads to see if that helps at all.
My old Eismann mags work so well, i hate to part with them! Any suggestions?
Fred 44051

[af1zaf1z]

Re: Comm Radio Box

Don't know if this belongs here, but here goes: Using an Icom IC-A20 handheld, a couple of DC H-10-13.4 headsets, and an old Telex PC-2 two place intercom. The problem is garbled audio ( unintelligible) when using the Icom handheld, with the intercom turned on. Intercom power off- problem gone. So talking to the tower or whatever, I have to find the power switch and turn the intercom off while using the radio. Anybody have a thought on this?/ Thanks Mark N44103

[Pearson]

Re: Comm Radio Box

Fred,

Please tell me, what is a "ferrite choke on the P lead"? I am familiar with shielded P leads, but have never heard of the ferrite choke.

[Pearson]

Re: Comm Radio Box

Mark,

I had the same problem when I first started using my Vertex handheld. It turned out the problem for me was the PTT switch built into the radio didn't work well with the intercom. I had to use an external PTT.

[Mark Julicher]

Re: Comm Radio Box

Fred,

Please tell me, what is a "ferrite choke on the P lead"? I am familiar with shielded P leads, but have never heard of the ferrite choke.

Ferrite chokes are made of iron and clay and are shaped like little donuts or tubes. Wires that need to be shielded are often passed through a ferrite choke. Since unwanted RF energy travels along the surface of a wire, the ferrite choke acts as a block. Surface energy is captured in the ferrite and dissipated as heat while the intended signal goes through the conductor.

It would be good to know if ferrite chokes offer any advantage on a P-lead.

[Pearson]

Re: Comm Radio Box

Thanks for the info! It sounds like the ferrite choke does the same thing as shielded P leads. Is that correct? Is one better than the other?

[astjp2]

Re: Comm Radio Box

I am doing something similiar for my transponder\encoder. It will have a 7ah Sealed lead acid battery and it will be portable. It will make my life easier to cross the Canadian border. The last time I got a squak code and just kept going with no electrical system. We had to keep looking over our shoulders to make sure the F-16's weren't chasing us as we headed out of the country. Tim

[Mark Julicher]

Re: Comm Radio Box

Thanks for the info! It sounds like the ferrite choke does the same thing as shielded P leads. Is that correct? Is one better than the other?

Great question. Short answer is they work differently and do different jobs.

Shielding captures the signal radiated from your P lead at each spark event and shunts the signal to ground. The shield should be grounded at one end so the signal will dissipate into the ground. A spark consists of many frequencies and the P lead is just a radiating antenna throwing all kinds of noise into the ether. Think of the shield as capturing a radiated signal inside a tin can. Ferrite toroids keep a signal from traveling along a wire and into a device. For example, if your radio is bleeding into your intercom, a toroid on every wire going into the intercom - as close to the intercom box as possible - should eliminate the bleed.

I knew a Ham radio operator in an apartment complex who, although operating legally, was "talking" to all the TV sets and telephones of his neighbors. He purchased a box of ferrite toroids designed to absorb amateur radio frequencies and installed them for all his neighbors. Everyone was immediately happy with their quiet appliances.

[Pearson]

Re: Comm Radio Box

Thanks for the explanation. I think I need to put shielded P leads on mine to eliminate ignition noise in the handheld.

[astjp2]

Re: Comm Radio Box

Dont put anything on a slick's p leads, it will mess up the mags per thier instruction manual. Tim