nigel1

Hi,

Does anyone know the country that uses the terminology TF & RF instead of TX & RX here in the UK Please?

i have purchased some crystals for FM 40 Mhz use in the UK they had the orriginal manufacturers name on the pack but do not seem to work in my UK radio, I was wondering if the frequency might be slightly off because they are meant for use in another country?

I have had some problems finding the right crystals for my Hitech Zebra radio and always seem to be fobbed off with something inferior to that of the orriginal specification.
however this time i thought I had it right as the packaging said Hitech.

kind regards. Nigel.

Rodney

To be safe, try to use crystals from the same vendor as the maker of the transmitters. Different tranmitters use different oscillator design (is it a Colpits, Hartley or ??) and may require a different cut on the crystal. Also, is it using a 3rd or 5th overtone crystal? Just going by the frequency marked on the crystal doesn't tell you all the necessary information.

A.T.

Refer answersfaulty Hitech Zebra 40mhz FM radio
Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links

nigel1

Alan T.

That doesnt really help much I'm afraid the terminology you use dosent tally with the information I have on my crystals.

onewasp

I have no idea what language/country would use capital 'F' where we use a small 'x'.

My advice/opinion is that if they can't get the abbreviation 'right' then I don't have much faith in the product-------particularly a crystal.

A.T.

Bait taken, hook line & sinker - How much faith can we have in products with "USA labels"? Much is OEM (manufactured ex USA) and just enough assembly and boxing done in USA to qualify for the made in USA label. According to other countries with English as a first or second language, spelling and abreviations used in USA are often mispelt or incorrect. Old established USA brands have been bought by offshore owners and whilst the brand appears unchanged, the product is no longer 100% American e.g. Ace R/C, Sig Mfg with 50% offshore ownership and old kits now prebuilt as ARF ex USA. All known Hobbico products are ex Taiwan & China. The country lists on my web page provide many places you can cross check products and note how many are identical except for the labels and price - you pay more for USA brand labels. e.g. Servo Metal Gear sets
FWIW the crystal tab abbreviations "TF" in lieu of "TX FM", "TA" in lieu of "TX AM", "RF" in lieu of "RX FM, "RA" in lieu of "RX AM" is clearer and has been is use for many years by brands other than Futaba. A manufacturer, who cuts and supply xtals to USA military, has confirmed that Hitec xtals are manufactured to higher specifications than Futaba and JR xtals.
Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links

onewasp

Interesting information.

Who'd a thunk it?

nigel1

So I have purchased a Tx crystal and an RX crystal in the same package marked Hitech crystals but the crystals have on them TF for FM transmitter and RA for AM reciever, if this is so accoerding to your infomation why would the crystals work when there are no other radios being used in the vicinity, if they are both of different frequencies surely they wouldn't work at all...Strange.

regards nigel1

nigel1

So I have purchased a Tx crystal and an RX crystal in the same package marked Hitech crystals but the crystals have on them TF for FM transmitter and RA for AM reciever, if this is so accoerding to your infomation why would the crystals work when there are no other radios being used in the vicinity, if they are both of different frequencies surely they wouldn't work at all...Strange.

regards nigel1

Rodney

nigal1. Typically a receiver crystal is 455 KC different than the transmitter frequency for single conversion receivers and 11.7 (approx) MHZ different than the transmitter crystal frequency for dual conversion receivers. Transmitter crystals are usually 1/3 or 1/5 of the frequency being transmitted (the transmitter usually multiplies the frequency of the crystal be either 3 or 5). That is why you can not use a receiver crystal as a transmitter crystal. Whether the receiver cystal is above or below the transmitted frequency is what determines whether the reciever is using positive or negative shift.

nigel1

Rodney,

Thanks for that but youve completely lost me in the great jungle of electrical knowledge.

regards. nigel1