Anyone know a good radio repair shop?

FORANE

FORANE

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FORANE
Some have followed my thread regarding the com radio issues I was having (squelch break and EGT readings up and down with clicks of the push to talk). Turns out the SL40 com has a short (not completely closed - there is some resistance) between the center post and ground of the antenna out.
This is not normal correct?

Anyone know of a good reasonable repair shop for a SL40?
 
Higginsville Avionics Lab in Higginsville, MO, but you probably don't want to go that far. KHIG LOL
 
What is "some resistance"? I would not expect an open circuit on the output of the radio, instead something in the vicinity of 50 Ohms. And then primarily in the frequency range where the radio is operating. Do you have a schematic diagram showing the output circuitry of the radio?
 
Ghery said:
What is "some resistance"? I would not expect an open circuit on the output of the radio, instead something in the vicinity of 50 Ohms. And then primarily in the frequency range where the radio is operating. Do you have a schematic diagram showing the output circuitry of the radio?
Click to expand...
About 15 ohm's if I was reading my ohmmeter correctly.
All I have is this:
http://www.mstewart.net/Downloads/sl40_IM.pdf

I checked the Garmin 430 antenna and it was an open circuit between center post and ground. I checked my CB antenna and it was an open circuit.

I just remembered, I have another SL40 in the RV. I will go check it tomorrow and possibly swap it into the Lancair tray to see if it resolves my issue.

I looked on Garmins website and the SL40 flat rate is now up to $550. If it is indeed the SL40, I suppose that is an option unless someone knows of another repair shop.
 
Confirmed, swapped out SL40's and problem solved. I have a bum SL40 radio.

So, is Garmin repair service the way to go?
 
Make sure you send it to the right place. I think all the old apollo stuff goes to Salem, OR. If you ship it to Olathe (like my idiots after I told them not to do so), it just wastes a couple of days while Olathe forwards it along.
 
flyingron said:
Make sure you send it to the right place. I think all the old apollo stuff goes to Salem, OR. If you ship it to Olathe (like my idiots after I told them not to do so), it just wastes a couple of days while Olathe forwards it along.
Click to expand...
Good to know, thanks.
I am considering weather I should send it to Garmin, Gulf Coast Avionics or Sarasota Avionics.
 
Garmin fixed rate service is OK. The Salem guys busted ass to get my MX20 fixed. The guys in Olathe, I'm less pleased with. When my Garmin audio panel took a dump, the fixed price as 1/3 of the new one and there was no loaner or other things I could do to expedite the horrendous turn around time and my plane was effectively AOG without the panel.
They were perfectly hunky dory happy to fedex me a brand new one if I wanted to buy one (anybody want a slightly broken Garmin audio panel?)/
 
I've had good luck with bench repairs at Penn Avionics in the past.


JKG
 
JGoodish said:
I've had good luck with bench repairs at Penn Avionics in the past.


JKG
Click to expand...
Penn Avionics...I will have to look them up. I tried calling Gulf Coast Avionics numerous times today but only managed to get ahold of an answering machine or voice mail or whatever we call it these days.

Took the SL40 out to the RV today to see if it had the same symptoms in the RV as in the Lancair. In the RV it did not break squelch as in the Lancair but it did slowly raise the analog EGT meter with push to talk click. Also, the analog ammeter showed varying amounts of drain from zero to -15 amps with clicks of the push to talk on different frequencies -very strange.

In any case, the Lancair needed the good SL40 from the RV and the RV needed a panel mount so today I bid on a GTN-650 on eBay figuring there was no way I would get it. Sure enough, I bought a GTN-650 today...

Anyone need a SL40 after I get the GTN installed?
 
weirdjim said:
Why would you expect 50 ohms?

.
Jim
Click to expand...

Note the next sentence. Around the frequency of operation. The output impedance typically would match the transmission line impedance (and input impedance of the antenna at the intended operating frequency). Typically we're using 50 Ohm coax, hence the output impedance around 120 MHz ought to be about 50 Ohms. Now, his Ohmmeter is operating at DC, so his reading of 15 Ohms probably isn't too far off. Nevertheless, the OP indicated that swapping radios solved the problem, so now he just needs to get the radio fixed.
 
Do you understand the difference between impedance and resistance? They use the same units but they are different. 50 Ohms impedance may read as either a dead short or complete open or anywhere in between when measured with a DC meter.
 
Ghery said:
Note the next sentence. Around the frequency of operation. The output impedance typically would match the transmission line impedance (and input impedance of the antenna at the intended operating frequency). Typically we're using 50 Ohm coax, hence the output impedance around 120 MHz ought to be about 50 Ohms. Now, his Ohmmeter is operating at DC, so his reading of 15 Ohms probably isn't too far off. Nevertheless, the OP indicated that swapping radios solved the problem, so now he just needs to get the radio fixed.
Click to expand...

It's way far off. The series resistance of a coaxial cable is going to be near ZERO and there should be no DC current between the shield and center conductor. The characteristic impedance for all practical purposes is purely reactive.

You are not doing anything attacking this problem with a DC meter.
 
Ghery said:
Note the next sentence. Around the frequency of operation. The output impedance typically would match the transmission line impedance (and input impedance of the antenna at the intended operating frequency). Typically we're using 50 Ohm coax, hence the output impedance around 120 MHz ought to be about 50 Ohms. Now, his Ohmmeter is operating at DC, so his reading of 15 Ohms probably isn't too far off.
Click to expand...


You are kidding, right? Or you have no concept of RF circuits. One or the other.

Jim
.
 
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