Yaesu FT-2900R

**S11D336B** · Sun 22nd Jan 2012, 04:35

Hey guys. I'm new to the ham community so bear with me.

I just got a Yaesu FT-2900R for my car. The radio works really well. I was able to hit a repeater over 100 miles away, no problem. However, I do have an audio amplifier for the stereo in my car. Since the power was already run for the amplifier, I simply used that power wire/ground for the new Ham mobile radio.

Ever since, I hooked it up and made my first transmission the audio amplifier no longer puts out sound like it used to. The sound is all garbled and makes bad cracking sounds. This continues even if I disconnect / turn off the Ham radio. . .

Do you guys have any idea what could have happened? If I have to replace the audio amp, I want to make sure I don't do whatever I did wrong again..

Thanks,
George

**5B4AJB** · Sun 22nd Jan 2012, 10:43

Sounds like you have had RF flowing through the DC leads back to the amp.

Did you mean the crackling persists with the Yaesu disconnected or just turned off?

If it is disconnected and still crackling, then maybe you have fried something in the amp. Probably not expensive to fix, but still another job.

It is good practice to run a separate power lead from the battery to a transmitter. Make sure you put fuses on the lead too...

**G4LNA** · Sun 22nd Jan 2012, 16:56

Hello George, welcome to the forum, what do you mean by 'hitting' a repeater?

**Orion** · Sun 22nd Jan 2012, 18:03

i guess he means he can access it

**S11D336B** · Mon 23rd Jan 2012, 03:08

Sorry for the delay in my response. I didn't get automatically subscribed to the thread so I didn't see your responses. I'm subscribed now.

Even after I disconnect the Mobile radio, the car stereo amplifier still has the same symptoms. Basically, it is fried. The right channel doesn't work and the left channel just makes cracking noises. What I'm looking for is a suggestion on what to do so that when I do replace the car audio amplifier I don't blow it up too.

The mobile radio has 25 amp fuses built into the provided power leads on the ground and power wires so that is good. I'm just a little dumbfounded that simply connecting the power wires near the car audio amplifier would cause a problem.

Originally Posted by 5B4AJB

Sounds like you have had RF flowing through the DC leads back to the amp.

Did you mean the crackling persists with the Yaesu disconnected or just turned off?

If it is disconnected and still crackling, then maybe you have fried something in the amp. Probably not expensive to fix, but still another job.

It is good practice to run a separate power lead from the battery to a transmitter. Make sure you put fuses on the lead too...

**S11D336B** · Mon 23rd Jan 2012, 03:10

Thanks. I was trying to say that the radio seems to be working as I get the confirmation tone from a repeater (which is quite far away). And others reported that they could hear me ok.

Originally Posted by G4LNA

Hello George, welcome to the forum, what do you mean by 'hitting' a repeater?

**5B4AJB** · Tue 24th Jan 2012, 19:02

I suggest you check the VSWR, a lot of RF power returning to the battery will cause all kinds of strange problems, especially with big MOSFET's (in your amp).

Wire your power leads straight to the battery using good connections and thick wires, with fuses on both leads (the fuses should be near the battery to keep them from continually blowing).

Try to keep the radio equipment away from speaker/line/amp if possible.

Double earth the amp, with a nice thick wire to the vehicle chassis.

It could have been a lot worse, you could have blown the car's CPU while driving...

**2E0JTP** · Wed 25th Jan 2012, 11:14

The FT-2900R puts out 75W at full power, that's a lot of potential stray RF if your setup isn't spot on.

The requirement for power wiring has already been mentioned, but have you checked your setup with an SWR meter and where and how is your antenna mounted on your vehicle?

**AJ4GY** · Wed 25th Jan 2012, 15:46

I agree with a lot of what people said. Run radio power directly to battery. What kind of car is it? and where is the antenna mounted? Also, agree with check your SWR. if you don't have one, go to your local club meeting. Hams are generally willing to help out.

**S11D336B** · Mon 30th Jan 2012, 07:38

Thanks for all the responses.

I have 8 awg from the battery to the amp (it is a fused line) which is under the passenger seat. I have the ground connected to the bolt which holds the seat down. I just took the wire which comes with the radio (which has fuses on the + and - lines) and connected it to the power/ground of the amp.

The car is a 2010 Mazda Mazdaspeed3. The antenna is mounted using a lip mount on the trunk right over the left light.
http://www.topcarspicks.com/wp-conte...AZDASPEED3.jpg

Lip mount:
https://www.hamcity.com/Store/pc/vie...&idproduct=727

Antenna:
https://www.hamcity.com/Store/pc/vie...idproduct=1029

I'll add the second ground too, this sounds like a good idea. I haven't pulled the amp out yet, but I'll probably do that tomorrow to see what the damage looks like.

Thanks guys.