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Futaba Tx Crytals 72MHz

#1
Require few Futaba Tx Crytals for 72MHz TYPE 72-7 or TYPE 72-9
Preferable Ch 32 (72.430MHz) or Ch 42 (72.630MHz) or anything :)
 

Piotrsko

Master member
#7
Been in this hobby a long time. My rocks don't have the other descriptor 72-7, 72-9. I can buy $5.00 @ set "AM" rocks all day long from non- FUTABA sources and they work. Ditto for the FM equipment I have but they don't interchange mostly from IF differences. A lot of purveyors don't understand the 72- system futaba uses but they do understand AM.
 

Rajib

New member
#8
Hello Piotsko sir,

I very glad to meet you, hard to find people like you who has long experiences in this old type radio system. I was feeling helpless long time back while searching information regarding this FM and PCM radio system and got no help from Futaba Japan. Whenever I used to wrote them about 72MHz their reply were always same that 72 Mhz used in USA so should contact Futaba Official USA Service. Anyway with time I came to some understanding about TYPE, this types are written on Original Crystals from Futaba only:

72Mhz:

TYPE 72-7 TX FM - Crystals ( Found in 4 to 7ch Tx)
TYPE 72-9 TX FM - Crystals (Found in 8 to 9ch Tx)
TYPE 72-10 RX DC FM/PCM - Works with FM/PCM both type of Rx models written on Dual Conversation, e.g. R127DF, R127DP, R129DP, R138DF, R138DP, R148DF, R148DP, R149DP, R168DF, R168DP etc
TYPE 72-12 RX FM/PCM (SHORT) - Works with FM/PCM both type of Rx models, e.g. R114F, R156F, R146ip, R136F, R137F, R136HP, R137HP etc.

Don't know much about AM because never get chance to use one but noticed that all crystals marked with TYPE 72-11 are AM crystals.

In 40MHz Band:

TYPE 40-1 TX FM
TYPE 40-6 TX FM
TYPE 40-1 RX FM
TYPE 40-6 RX FM
TYPE 40-10 RX DC FM/PCM
TYPE 40-12 RX FM FM/PCM (SHORT)
TYPE 40-9 TX AM
TYPE 40-11 TX AM
TYPE 40-11 RX AM

I am always curious about all the letter and numbers written by the company on their products, sometimes they give abbreviation of those letters sometime don't. But if you ask the manufacture they behave like you have asked some secret formula or design :-D I would love to know some more details about this old radio system and all the meaning of those letters on the Rx model. Correct me if I am wrong about them. On the Rx before DF/DP/iP/DPS the first number always represent the channel numbers of the receiver but what about other numbers meaning?

R = Receiver
i = ?
F = FM
D = Dual Conversion
P = PCM
H = Helicopter (guessing only)
S = Synthesized ( e.g. R319DPS)

Waiting to learn something more from you :)
Regards,
Rajib Samadder
 

Piotrsko

Master member
#9
I haven't had reason to decode any the futaba codes but i knew stuff from radio transmission. Channels are different base frequency offset by maybe 100khz.

The transmitter rock is offset by some intermediate frequency either higher or lower than the base frequency and ditto for the recieve rock. Btw: rock is slang for the quartz crystal, well, because it is a chunk of quartz rock. Since everybody kinda uses the same IF standards, crystals mostly exchange between makers, so as i said earlier, futaba, cirrus, hitech JR airtronics, and others exchange but not for am to fm. 2.5 gig Pcm stuff is internally generated frequency with a phase lock loop to keep it stable so you wont need crystals there and that's why AM/FM should be your only 2 choices except for the ham bands of approximately 8 meters. If you're in the ham band, you know enough to order your own stuff. 2.5 gig stuff also doesnt offer crystals for sale because it would be pointless on frequency hopper equipment.
 

Piotrsko

Master member
#10
Continuing on: back in '75 or '76 the Fcc had allocated enough spectrum that stuff was getting crowded, so they had to tighten up the transmit sidelobes on RC and reduce power. In the late 80's or '90s they decreed that you couldn't change channels on AM Equipment so those radios are stuck on that frequency more or less, FM became big because the specs were tighter, you COULD change channels, and they were less prone to interference and the Fcc changed channels for ground air and controls because we were interfering with commercial interests. Around 2000, computer controlled radios became the big deal, still on FM, but sometimes on the 2.5 gig band, but you cant change those 2.5 ghz frequencies.

So there it is: if it has exchangeable channels it has to be AM or FM.

[RANT OFF]
 

JasonK

Participation Award Recipient
#11
Continuing on: back in '75 or '76 the Fcc had allocated enough spectrum that stuff was getting crowded, so they had to tighten up the transmit sidelobes on RC and reduce power. In the late 80's or '90s they decreed that you couldn't change channels on AM Equipment so those radios are stuck on that frequency more or less, FM became big because the specs were tighter, you COULD change channels, and they were less prone to interference and the Fcc changed channels for ground air and controls because we were interfering with commercial interests. Around 2000, computer controlled radios became the big deal, still on FM, but sometimes on the 2.5 gig band, but you cant change those 2.5 ghz frequencies.

So there it is: if it has exchangeable channels it has to be AM or FM.

[RANT OFF]
the 2.4GHz stuff jumps around on different channels automatically and does collision detection, which is why we don't need frequency boards anymore. The system automatically deals with signal collisions (at least for the most part) automatically.
 

Piotrsko

Master member
#12
Go read Hai Lee's treastie regarding how this newfangled stuff works and you'll find that there are provisions in the equipment that preclude that scenerio. They listen before they talk so they cant talk over someone else, which is why there is a limit to how many transmitters can be ON at the same time.
 
#13
Go read Hai Lee's treastie regarding how this newfangled stuff works and you'll find that there are provisions in the equipment that preclude that scenerio. They listen before they talk so they cant talk over someone else, which is why there is a limit to how many transmitters can be ON at the same time.
Would love to read, can you please give me the link, I tried to search but can not find it other than a fashion model lady's page.