wejaz28

I have an older model (91') airtronics vg6 Tx (Fm, 75mhz, ch56)

I purchased a Cirrus MRX-4 Single conversion Rx for a park flyer.

I also purchased a ch56 crystal for the Rx.

Problem: DOES NOT WORK !

Tx works fine with full sized Rx it came with.

I tried the crystal from the full sized Rx in the Cirrus Rx to no avail.

1) Do I have the right crystal, or do I need a specific one ?
2) Are these items compatable ?
3) What are my options ?

Thanks in advance, Weja

blvdbuzzard

When you bought the Rx, did you get one that has the same shift as the Airtronics??? Is the Rx on 72MHZ or 75MHZ??

Dru.

Airbike

My Feedback: (6)

I use an Airtronics RD6000 with several Cirrus MRXII Rxs with no problems.
Make sure you are using a Cirrus single conv Rx crystal and not the dual conv one.

Imac Kiwi

I think you will find that the rx you purchased is on the 72mhz band, and the xtal is Ch #56 on the 72 mhz band. This will not work with a surface radio on 75mhz.

wejaz28

Thank you for the quick responses.

1) I listed 75mhz, should have wrote 72mhz (Not a surface radio).

2) This is the single conversion MXR-4 Rx, not the MXR-4II.

3) It has "For use with Airtronics" (Postive shift ?) on Rx.

4) So, a Single conv crystal is needed in the Rx even if the Tx is Dual conv?

5) It says on the package that crystal is for "MXR-4II.

Thanks again, Weja

Scar

My Feedback: (3)

Cirrus makes an MRX-4 Mark II receiver. I can't find any MXR items.

The MRX-4 is designated a "Single Conversion" receiver, that's just a short description of how the receiver handles the transmitter signal. It will require a crystal that matches.

The transmitter does not have a "single conversion" or "dual conversion" designation. It transmits on a 72MHz carrier frequency specific to the channel number. The AMA webpage or handbook shows the relation between channel number and specific 72.xxx MHz frequency.

A Channel 56 FM transmitter signal can operate any channel 56 FM receiver, be it single or dual "conversion". However, the receiver must be equipped with the proper crystal.

Sounds to me like you have inserted a dual conversion crystal in a single conversion receiver. You might call up the place where you bought it, and exchange information. They will probably help you.

Good luck,
Dave Olson

wejaz28

Thank you Dave. I will check on the crystal conversion tomorrow.

Weja

wejaz28

Uh oh ! I took the crystal back the the Hobby store and exchanged it for a "Hitec" channel 56 single conv crystal. Everything seemed O.K. during bench instal and test. Went to the field and did a range check. tested ok.

Turned the plane on and applied full power, plane glitched a couple of times when I neared the radio to the plane. So I moved it away and sent her up. It got about 100 feet from me flying straight, then lost control and dove straight into the ground.

I don't get it. The guy I talked to today (When I returned the crystal) said he has used Hitec crystals in a Cirrus Rx before with no problems. Think I will be trashing the Rx....

What could my problem be now?

Weja

Scar

My Feedback: (3)

Sorry to hear about that crash! Have you flown much? I'd like to know why the plane glitched, and how much. Without knowing how much you've flown, and what the glitch problem was, we can only guess.

What kind of plane, what kind of propulsion system, was the receiver antenna run clear out the back, was the transmitter antenna fully extended, and were there other planes flying in the area? And when I ask what kind of plane, I mean did it have rudder, aileron, elevator & throttle control, was it high wing or low, biplane or shoulder wing, and was it electric power, or what glow engine.

More information is better.

Good luck,
Dave Olson

wejaz28

I have been flying gas for 20 years. Just got into electrics to fly with my daughter at the park.

The plane is a "Accipiter Badius" (High wing powered glider, flies nice) with different ESC and Rx (obviously). the rest is stock, 370 motor-direct drive, 700mah Nicad. I changed radio because of mode 1 Tx it came with.

The plane flew great with the standard Airtronics Rx. I just wanted something a few ounces lighter in it. Rudder/elevator controls.

Glitch was full deflection of rudder and lack of throttle control. Happened a few times when Tx was near plane. Rx Antenena was run out back (same as Airtronics Rx), Tx antenna fully extended. I was flying in school field with no other planes around. I did not lose control, plane did not respond to controls and went nose down from about 30 feet (no damage!, tough little plane).

Tx/Rx batteries were just charged.

I've never really got into the radio side of flying, just installed what I had and flew. Never had any problems until now, but never switched Rx's before...

Thanks, Weja

Airbike

My Feedback: (6)

Weja, Sorry about your crash. You should take everything back to the store and see if they can't help you out since they sold you a Hitec crystal for a Cirrus Rx.
I suppose the employee experience level just varies too much.

You SHOULD NOT mix Rx crystals. You need to use a Cirrus crystal with a Cirrus Rx and a Hitec Crystal with a Hitec Rx. (and single conv crystal for a single conv Rx)
While they always seem to work on the bench, there are no reassurances that they will work without problems later on.

I have seen some advertisements for certain Rxs that can use several different crystals, but I don't think that was Cirrus.

I had to mail order a single conv crystal for my MRX-4II from Hobble People as the local stores did not have my channel in stock. I just figured the shipping and handling charge would be less than a couple of gallons of gas to drive around.

Scar

My Feedback: (3)

Wejaz,

Good description and information, and it sure is a puzzler. I'll endorse everything Airbike said, but I have one additional response.

It sounds to me like it flew out of range. To verify (or rule out) would require a range check, with the existing system. I'm sure you have your methods, but mine would be to collapse the antenna, point the antenna straight at the plane on the ground, and walk backward until it either glitches fulltime, or loses control. If that's less than about 80 paces, we can debate further, and if it's more than 100 paces, the consensus is that the range is adequate.

At our field, there's an alternate theory, I believe it involves wormholes, or moleholes, or some such Black Magic theory. Good as any, I guess. Hope your next one range-checks out to 200 paces!
Dave Olson

wejaz28

Scar,

My range check is similar to yours. My 5 year old does not know to announce a glitch in the radio. I saw the control surfaces move as I backed away, but it could have been glitching as well. I stopped at about 100' due to the size of the control surfaces. I assumed it was O.K.

The plane was no more than 150' from me when it nosed straight down.

I am going to try one more time. I ordered a Cirrus crystal ch56, part #446156 from Hobby People.

If that don't work, can anyone recommend a decent micro Rx for my old Airtronics Tx?

Thanks, Weja

JohnBuckner

My Feedback: (1)

Hitec 555 - very small adaquate for most electrics, full performance, full range dual conversion, five channels. The most reliable Rx I have ever experianced and use 16 of them. Of course only use Hitec dual conversion crystal and order it with positive shift and old style Airtronics plugs if that is what you have.





John

wejaz28

Thanks John