Thorp Air Command - T18.net

This problem came out of the blue . I was in the driveway running the engine to warm it up for an oil change and was listening SOCAL Approach...nothing better to do . Radio working fine and squelch could be turned up and down no problem . My Microair has a green lite that comes on when the squelch is turned up . Shut down , changed oil and tugged the AC back into the workshop . I had been having trouble with the fuel gauge bouncing around and knew it was just a loose connection . Tilted the panel found the loose connection . As I always do I power up the panel and check that everything is working . This time my green squelch lite is on and I can not turn it off with the squelch knob ? I know what you are thinking...another loose connection . I went thru everything and found nothing . If I remove the coax antenna connection from the back of the radio the lite goes out . OK...maybe the radio ? I have a spare radio and put that in only to find the same problem with the squelch . Bad coax connector ? Replaced it . Same result . Have a spare antenna and premade coax and attached it to the radio . Works 4.0 ?

Now I start to work down to the AC antenna . I disconnect the coax from the AC antenna and attach it to the spare antenna . Works 4.0 ? Must be a bad ground on the AC antenna . Removed the AC antenna cleaned all the attach screws , mounting holes and the skin inside the AC and the doubler mounting plate . Put it all back together and can not get the squelch lite to go out ? If Mr. Wizard is out there tell me what I am missing !

RB

Measure with a Dvm from center connector to ant. Base then check the one that works ant could be partially shorted ohms scale.

Lance

I'll try that , but it seems strange that when I disconnect the original coax installed in the AC at the ant. and hook up the spare ant. (ant not installed in AC , but grounded) the Squelch works . It even worked when I removed the RAMI AV-17 ant. from the AC and hooked it up to the current coax ? >:(

What reading should I see on the Ohm meter ?

RB

Depends if it is a loaded ant. But you did all the right things and sounds like you isolated the problem you will probably get a very low reading, compair the readings between both antennas. Look real close at the base of the ant and see if you can see any foreign substance.

Lance

Friday the 13th and a full moon.....

_________________
Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

Thanks Lance . I'll do the readings in the morning . I'll been in and out of that cockpit at least 10 times today and the same for the last 3 days . When I removed the AC antenna , I cleaned everything . The only thing I did not do is remove the rubber gasket that goes between the ant. base and the bottom of the AC . The installation instructions state the ant. gets it's ground from the 4 screws that attach the ant. to the doubler plate inside the AC . If the ant. attach points were any cleaner they would have to testify before Congress and plead the Fifth !

Full Moon ? The only full Moon I see is your Arse hanging over your patio balcony after a few Barley Pops !

RB

I suppose you towed the plane out of the garage/hangar and checked it. Could be interference from some source in the house (air conditioner?). Even fluorescent lights can mess you up.

_________________
Bob Highley
N711SH
SN 835
KLAL

Bob: At this point I'll try anything . The panel was built and tested in the shop and the radio has work flawlessly for over 3 years . I'll tow it out into the driveway and give it a try . The spare radio does the same thing . It's also about time to do a wire wiggle test also . It has to be something simple that I am over looking ?

RB

Bob...you the man! I had never had a problem with using/testing the radio in the shop/hangar until now . I towed the AC back on the driveway , powered up the radio and the problem went away ! BOOM ! One possibility is that I just remodeled the hangar putting down a new epoxy on the floor , installing several new metal cabinets and moved around and repositioned the big iron machinery . I owe you the beverage of your choice along with lunch . Thanks Bob . You saved me many more hours of trouble shooting .

RB

dang! now that is something....never in a million years would I have figured that one out.

Sooner or later I would have gone back to square one where the radio did work ...in the driveway . Bob put the idea in my head a lot sooner ! I think it was the addition of the metal cabinets and repositioning the shear , brake and 3 large metal tool boxes .

RB

I think that the tool cabinet , and the 3 tool boxes you had rearranged on top of the radio could have been the culprit, just can't figger out how you got em under you panel?? Dan

Very carefully ! Plan to arrive at U-42 around 1230 (L) ? Fuel stop at St. George .

RB

Never take anything for granted . I pulled the AC back onto the driveway and I had Sil with the handheld drive up and down the street for a radio check . OPS normal . I then tugged the AC back into the shop but is a slightly different spot...you guessed it the squelch worked ! This ends my squelch thread . BOOM !

RB

I still think it was Friday the 13th and a full moon that caused it....

_________________
Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)