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Other › once again... Tx/Rx not communicating right???
05-09-2005 02:31 AM  12 years agoPost 1
WRXRonald

rrKey Veteran

Auburn, OH

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what the hey is going on here... argh i'm pissed...

so everybody remembers helping me figure out how to get the Tx to 'chat' with the Rx correctly and teaching me about why we only swap Rx crystals and not Tx crystals.......

So i went out and ordered the correct Rx crystal for my new 7chp... while waiting i 'broke the law' as dshkema would point out and swapped my Tx from the correct channel 13 to channel 20 to match what was already in the Rx.

works ok. but today had problems and glitches about 300 feet distance and lost the bird into a crash.

The reason this happened was because despite everyones advice, i am STILL unable to match the right Tx to Rx crystal.

i went to TowerHobbies site and looked at their "futaba dual conversion Rx crystals"... purchased 72.050 channel 13 to match my Tx crystal 72.050 ch13.

got it the other day and install into the Rx and get nothing. tried both ppm and pcm on the Tx, still nothing. the Tx crystal has black sticker and says "FM" on it. the Rx crystal i got from Tower has RED sticker and says "dual conversion" but not FM on it???

What the heck am i doing wrong? i thought i could buy any dual conversion Rx as long as the channel and frequency/band or whatever was a match to my Tx and be all set here. but i'm not. Especially ticked cuz Tower's site said "futaba crystals" and my Tx is made by Futaba, and my Rx is made by Futaba? so now i'm lost, and clearly i don't think using the wrong Tx crystal in my Tx is a good idea, cuz the range appears to be quite reduced.

any help or suggestion would be appreciated.

thanks,
Ron

Good Day: crashed thx to dumb thumbs. Bad Day: crashed mechanical malfunction. Every Day: CRASH :)

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05-09-2005 05:57 AM  12 years agoPost 2
dkshema

rrMaster

Cedar Rapids, IA

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First, you need to quit fiddling around with the TX. By messing with it, you have introduced a whole second set of variables and only complicated your trouble and increased your frustration level. And yes, you are now an outlaw for that dastardly TX crystal swap.

I looked back at your previous post, you were'nt too clear about what RX you are having trouble with.

As far as I can tell, you have an old T6XHS system, and a new 7CHP.

The T6XHS shipped with the R127DF receiver if it was an FM system, and it shipped with the R138DP or R148DP if it was shipped as a PCM system.

The 7CHP ships with an R138DP for the PCM setup.

Assuming that you have a new 7CHP, you have an R138DP receiver that came with it. This is a dual conversion, PCM RX.

Assuming you are using all Futaba receivers here, the older T6 system was a dual conversion RX, and the new 7CHP is also a dual conversion RX. Both frequencies are in Futaba's "low" band, so you should have no problem with your old receiver or your new receiver when switching between your two channels (72.190 and 72.050).

The correct crystals are indeed the "low" band, dual conversion Futaba crystals. It looks as if you got the right crystals.

So, here are the tough questions:

Which receiver do you have that came with your T6XHS system?
Which receiver do you have that came with your 7CHP system?

Are you trying to use a non- Futaba receiver here? If so, which brand?

Which transmitter works with which receiver, with no apparent problems?
Which transmitter appears to have problems with which receiver?

Does the "bad" receiver work with ANY of your Futaba systems with no problems?

Answers to these questions may help pinpoint what's going on.

It may be that you simply have a defective receiver in the mix somewhere. Possibly a broken ceramic filter inside that's part of the IF stage.

Dave

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05-09-2005 02:28 PM  12 years agoPost 3
WRXRonald

rrKey Veteran

Auburn, OH

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ok...

first let me say thanks dave... good questions and appreciate you helping me get to the bottom of this.......

Bird came with a T6XHS and a Futaba Rx: PCM1024, R136HP, 72.190, always worked fine.

The T7CHP came stand-alone, no Rx or servos with it.

So i am trying to adapt the 7CHP to work with the R136HP. worth noting the 7C manual tells me it should work with any futaba pcm1024 Rx, and as long as it was low band (ch 11-36 or something), no Rx tuning should be necessary.

Since the 7chp came on 72.050, i went to tower's site and ordered from Futaba crystals dual conversion 72.190 (oops, ordered wrong one, back to the site again, order again... this time 72.050 dual conversion)

The R136HP initially had 72.190 in it, along with the T6xhs, and always worked fine, and still does. Also the setup works (at least at moderate to short distances) if i put the 72.190 from the T6 into the 7C -- of course this is a no no, thanks only to my impatience for making this mistake.

What is not working is when i switch back to the correct crystal on the 7C, 72.050.... and put the new tower Rx crystal into the R136HP (the 72.050 one), effectively making both the 7C and the R136HP match channels-- thus one would expect them to be working together. Tried both PCM and PPM settings like this, to no avail.

Turn them both on, get nothing but a flashing ESC and nothing communicates. Switch them (the 7C and 136HP) both back to 72.190, and voila, they work. or put the 72.190 in the T6, agin voila, they work.

??? got me. did i screw it up cuz I started use of the 7C with the wrong crystal right from day 1. Now maybe the 7C is screw-geed?

thanks again..... (also worth noting... both the Tx and Rx crystals have "type" markings on them, ie TYPE 72-7 or TYPE 72-12. do these matter at all, the 'type #' is different on all my crystals.

Good Day: crashed thx to dumb thumbs. Bad Day: crashed mechanical malfunction. Every Day: CRASH :)

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05-09-2005 06:58 PM  12 years agoPost 4
dkshema

rrMaster

Cedar Rapids, IA

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Am I seeing correctly, is my monitor going weird, did you type the wrong RX type, or did you actually mean to type that the RX is an R136HP?

I looked at the Futaba site, at their old receiver listing, and their new receiver listing...

I don't see anything like an R136HP listed.

The type numbers on the crystals -- 72-X -- I'm guessing that the 72 tells them it's a 72 MHz crystal, and that the number after the dash tells them which channel it is. I believe you got the right crystal.

I'll re-read your post this evening -- and see what else I can help figure out.

Dave

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05-09-2005 07:10 PM  12 years agoPost 5
rckrzy1

rrElite Veteran

Hurst Texas

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Just help or confuse some more.

Single or Dual conversion have nothing to do with am/fm/pcm , it's
just the number of mixes used to get to the IF frequency.

And a crystal should work or not , I don't see range being affected
unless the crystal is cut to the wrong freq or is very old or damaged.



Wildcat Fuels

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