SANWA FM Receiver info needed?

[wldnas]

Hi, I've just been given a set of Servo's and Receiver to test from my cousin, it's an old SANWA FM type set, I've tested out the Servo's and Battery box/switch on another compatable Sanwa Receievr I have and they all wok OK, but I cannot get a peep out of the original receiver

It's quite possible that the RX is shot (cos the aerial lead has been cut off, nots normally a bad sign :S ), but then again I'm not even sure if I'm using the right frequency as it came fitted with a funny type of crystal that I've never seen before?

The RX has a sticker on the top saying "USE SANWA CAP TYPE X'TAL" rge Crystal cover is marked up as 35.190Mhz FM RX 79 but the Crystal itself is a D34735 Toyo Com 2B? now I've been trying to get it to work using an old Futaba FP-T4L and my Hi-Tec Lazer 6 with a veriaty of FM 40Mhz X'tals but to no effect?

what I want to know is would these work at all? if so then it's obvious that the RX is kaput? if not then what TX and X'tals must I use to get it to work?

suggestions please :S

BTW: while were on the subject of strange radio gear that I can't seem to get working? I also have a weird Transmitter that I can't figure out what frequency it's on, I've tried every combination of of FM and AM frequency I have but can't get nothing out out of the thing, not even static?

The Transmitter is a Graupner (JR) Varioprop SSM 40 E4 there is some german writing on the bottom (SSM-Schmalbandsystem . Kanalraster 10 Khz) on the back it has the writing (Graupner MF-95/81 Varioprop E4SSM40) the X'Tal markings are (52 T SSM) on the cap and (type 72-5 AM 72.830Mhz on the Crystal)

now apart from the marking on the crystal there are no clues on the TX as to what frequency it is? I've tried AM and FM, 35,40 and 75 Mhz but noting seems to work at all the TX itself is in good overall condition, it powers up when batteries are put it so I can see no reason why it shouldn't work? any clues as to why :S

[Twmaster]

Sounds like that receiver is a US 75 Mhz ground Band model. Possibly even on Channel 79! Pay no mind to the odd frequency on the crystal it's self. The JR Alpina set I have also has a goofy frequency stamped on it's crystal which curiously enough is also channel 79....

As for the Graupner it sounds like 40 MHz but the numbers on the crystal indicate 72 MHz aircraft band (US).

You seem to have quite a pile of odd stuff Jason.

[wldnas]

Hi Mike

the trouble is that US 75Mhz is AM frequency? this Sanwa RX I have is FM and I don't have a compatable FM TX to use with it :S I've got no FM 35 Mhz Crystal seta that I can try out either?

still thanks for your info any advise is appreciated

[Twmaster]

Here is a link that may help:

http://www.rctek.com/radio/rc_model_car_ra...requencies.html

One other thing to remember, (I don't know if this holds true for 40 MHZ but it does for 72 and 75 MHz) You cannot mix RX and TX on some brands of radio gear due to a thing called frequency shift. JR and Sanwa (Airtronics) use positive shift. Acoms, Futaba and Hitec use negative shift. Typically you can use another brand receiver if it is on the same channel and is the same shift as well as modulation type eg AM will not work with FM. Also, you typically cannot use the crystals from another radio brand eg Sanwa in a JR. Sometimes it works but more oft than not it is a very bad idea.

Hope that is of some help.

[Twmaster]

quote:Originally posted by wldnas

Hi Mike

the trouble is that US 75Mhz is AM frequency? this Sanwa RX I have is FM and I don't have a compatable FM TX to use with it :S I've got no FM 35 Mhz Crystal seta that I can try out either?

still thanks for your info any advise is appreciated

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id="quote">id="quote">

No 75 MHz uses both AM and FM. I have JR, Hitec and Futaba radios that are FM and I also have JR, Futaba and Hitec radios that are AM and *all* are 75 MHz. (I am sure you are ready to scream now! []

As I said before, the frequency stamped on the crystal may not make any sense. The lable on the holder or the paper tag you see on many crystals is the important identifer.

Happy to help if I can.

[raemin]

Old sanwa receiver requires specific crystals (green ones).