Transponder help

As I continue to attempt to finish up my electrical system Iam having a problem Im hoping someone has seen or knows what I should do to remedy the situation.

I have a Vertical Power Sport, and from that I am powering my strobe lights (Strobes N? More) and my transponder (Garmin GTX327). They are on separate circuits, and operate with no defects EXCEPT....when the transponder is turned on and the strobe switch is selected on the transponder ?reboots?. This is the only device that is causing it to do that. Turning the strobes off has no effect on transponder operation (good). The transponder is grounded at the firewall with the majority of all other items. The strobe power supply box is grounded to the airframe and I have it located just behind the baggage compartment bulkhead. Power to the strobe is independent. Power to the transponder is on the avionics buss which also includes the EIS, and Comm and neither have any issues when strobes are selected on. Battery voltage is 12+ volts. Was thinking of trying to wire the transponder directly off the main battery in lieu of the avionics buss and see if that changes anything, but perhaps someone here has a better idea.
Thanks

I?m not familiar with the strobe system, but it sounds like there is a momentary high draw when the strobes are turned on that is dropping your voltage low enough to cause the transponder to reboot. Probably wouldn?t happen with a running engine with the alternator supplying power. With an alternator on, voltage will be closer to 14V.

I wondered about that Jay, but I discounted it as it didn?t happen to my EIS nor my Comm. My reasoning was that I am assuming they would all pull similar amounts of power, but maybe the transponder is the most sensitive to it. I guess the only way to see is start the engine, but Iam still a month or two out from doing that. Thanks for the response.

I just checked the agar in manual. It does say 11-33 volts. Might just be a blip below 11 causing it

Could be. I guess I could hook up another battery to give me more capacity or perhaps a battery charger and see what happens. The more I think about this, it has me thinking that you are probably correct in your thought process, and that if I start the engine the alternator should provide more than enough juice to keep everything running. The battery that I am using to do my check outs is just a 12v lawn mower battery that I bought for $15 for just this purpose. I would have to look, but would doubt it has much capacity for this set up which it was not designed for.

Cleco 97 said:

Could be. I guess I could hook up another battery to give me more capacity or perhaps a battery charger and see what happens. The more I think about this, it has me thinking that you are probably correct in your thought process, and that if I start the engine the alternator should provide more than enough juice to keep everything running. The battery that I am using to do my check outs is just a 12v lawn mower battery that I bought for $15 for just this purpose. I would have to look, but would doubt it has much capacity for this set up which it was not designed for.

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I made my own GPU using a variable voltage 30A power supply. It worked well for testing since I was able to check everything out at 13.7v rather than 12v. It also let me charge the Dynon backup battery while on the ground, since it won't charge when you are running off just battery power.

If those are old school strobes instead of LED, then there are some large capacitors that need to rapidly charge when power is applied. I was able to find a power supply on eBay for about $20. Just search for LED sign power supply. It was 12V and 30 amps and it has an adjustment to tweak the output

Cleco 97 said:

SNIP... The battery that I am using to do my check outs is just a 12v lawn mower battery that I bought for $15 for just this purpose. SNIP

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Tom,
You should have included this tidbit in our original post.

My standard recommendation - never run any avionics on anything other than a real battery (like the kind you will fly with) or for bench testing and hangar flying, a real power supply. NEVER run avionics with a battery charger connected to the battery.

Many options, but here is a very nice, light weight 30 amp regulated supply with variable voltage output, voltage and current meters: https://www.dxengineering.com/searc...+brand:mfj&sortby=Default&sortorder=Ascending

With this you can run everything on the panel and rest of the plane as well as charge the battery(s) just like your alternator will do.

Carl