RC India

RC Baazar => Wanted => Topic started by: manojswizera on December 14, 2011, 07:57:55 PM



Title: Need of FM crystals
Post by: manojswizera on December 14, 2011, 07:57:55 PM
Friend any one have fm crystalls , 72.490.  or any other 72mhz . i need two crystalls.


Title: Re: Need of FM crystals
Post by: AEROVISHWA on December 14, 2011, 08:03:03 PM
check on ebay ....there are  many.....


Title: Re: Need of FM crystals
Post by: anwar on December 14, 2011, 10:12:07 PM
You have to also specify shift, size and conversion types, unless you are going to build circuits around these.


Title: Re: Need of FM crystals
Post by: manojswizera on December 15, 2011, 09:40:11 AM
Anwar sir ,  i dont know SHIFT, conversion type.  what are they ?
just i am attaching a pic of FM RX 72.490 ,  TX FM is also same.


Title: Re: Need of FM crystals
Post by: AEROVISHWA on December 15, 2011, 09:55:52 AM
which brand is your radio, which model...?? and u want it for Tx or  Rx..??


Title: Re: Need of FM crystals
Post by: manojswizera on December 15, 2011, 10:07:55 AM
My Radio is E-SKY  6 channel , model no 0406A. PPM, 72 MHZ.
i want both TX and RX crystals .
Problem is that my radio is not working, as discussed with senior members ,they told to replace the crystals and check, bcoz i dont know the problem is with which crystal.
my Radio is same as here in link with  HELLYFLIER

http://www.rcindia.org/for-sale-completed/esky-6ch-tx-rx-for-sale/msg84023/#msg84023


Title: Re: Need of FM crystals
Post by: anwar on December 15, 2011, 10:18:27 AM
Anwar sir ,  i dont know SHIFT, conversion type.  what are they ?
just i am attaching a pic of FM RX 72.490 ,  TX FM is also same.

Differences in crystals (ie, FM transmission types) :

http://www.rcindia.org/radios-and-receivers/understanding-radio-functioning/
http://www.rcindia.org/radios-and-receivers/fm-receiver-choices/

And according to these threads :

http://www.rcuniverse.com/forum/m_6957235/tm.htm
http://www.rcgroups.com/forums/showthread.php?t=710621

... what you need is negative shift (Futaba/Hitec standard) crystals.  Full size (not mini size), and single conversion too.





Title: Re: Need of FM crystals
Post by: manojswizera on December 15, 2011, 10:51:50 AM
Thanks Anwar sir, for those links.


Title: Re: Need of FM crystals
Post by: rcforall on December 15, 2011, 12:45:23 PM
We have 72 mhz paired crystals from GWS :
72.110 , 72.210,72.390 .72.550,72.690,72.870  single conversion
72.270 : dual conversion

72.150 , 72.670 , 72.550 single conversion ( regular un branded )

72.870 ESKY ( paired )

Only Rx crystal ( unbranded )
72.670

So you could use any of these with your radio by replacing both crystals.

Sai


Title: Re: Need of FM crystals
Post by: manojswizera on December 15, 2011, 01:44:00 PM
Sai, Sir i want      72.870 ESKY ( paired )  Crystals, they are not on the rcforall site . At what price i can get them.


Title: Re: Need of FM crystals
Post by: sandeepm on December 15, 2011, 02:36:41 PM
i have 72.810 Crystals for tx and rx both. If interested..then please suggest me your buying price.
Sandeep


Title: Re: Need of FM crystals
Post by: anwar on December 16, 2011, 12:08:13 AM
It is not a very good idea to change the TX channel drastically.  If you want, get the nearest to the original (something between channels 33 and 37).

See the discussion here... this is something we often forget :

http://www.rcindia.org/radios-and-receivers/can-we-change-the-mhz-of-radio/msg14566/#msg14566


Title: Re: Need of FM crystals
Post by: manojswizera on December 16, 2011, 10:18:58 AM
Sorry anwar sir, i dont get cleared , as the pic of my crystal i have posted FRONT view it is written 35, and other pic OF back side is written 72.490.   So does it mean the channel is 35 and frequency is 72.490.
If i am wright , you mean that i should use channel near to 35.
or i should use frequency  near to 72.490  ?
I am getting crystals of  72.450 and channel 21 and 14.
should i use them, or they wile be useless.
Sorry for so many clarification.


Title: Re: Need of FM crystals
Post by: anwar on December 17, 2011, 10:02:57 AM
Please do a little bit of reading up on the item you are trying to procure, it really helps to have a basic understanding of the technology and related choices.

How channels relate to frequency in 72Mhz : http://radiocontrol.wikia.com/wiki/72_MHz

If you are changing TX crystals (sure you would have to find the matching RX crystal also!), I would suggest you use something close to 72.490, so 72.450 (channel 33) would be a good choice as it is not too far away.  This would optimize range/performance.