True sine wave oscillator for RF

Thread Starter

Vindhyachal Takniki

Joined Nov 3, 2014
562
1. Looking for a true/pure sine wave oscillator of fixed 40.68Mhz to drive this ckt: https://www.mouser.in/ProductDetail/NXP-Semiconductors/MRF101AN-40MHZ?qs=T8HDo%2BTk69V2c0bO8xVorg==

2. Found one source : https://www.digikey.com/en/products/detail/crystek-corporation/CRBSCS-01-50.000/4741142

3. Most of other sources I found of oscillator are not sine wave, but this company seems to less popular. So any other brand which is more popular. Crystal should be sine wave though only at fixed 40.68Mhz only.
 

MisterBill2

Joined Jan 23, 2018
7,234
The simple way to have a sine wave at any specific frequency is to feed it to a high "Q" resonant circuit at that frequency. But if you are feeding a mixer or a multiplier probably a square wave would work better.
For more detailed help you will need to also mention the power level and the circuit impedance value.
 

Papabravo

Joined Feb 24, 2006
14,655
Most RF circuits neither produce nor require a pure sine wave. In fact distortion is the penalty you pay for efficiency in a class C, RF amplifier. The only thing you can hear is the modulation that is added to the transmit carrier and removed by the receiver. Can you explain the necessity of your requirement?
 

bertus

Joined Apr 5, 2008
20,869
Hello,

40.68 MHZ is in the middle of one of the ISM bands:

ISM 40.68 MHZ.png

As for type B:
Type B (footnote 5.150) = frequency bands are also designated for ISM applications. Radiocommunication services operating within these bands must accept harmful interference which may be caused by these applications.

https://en.wikipedia.org/wiki/ISM_band

Bertus
 

SamR

Joined Mar 19, 2019
2,762
Used for RC toys, anti-theft hospital baby bracelets!?! (automatically locks down doors if an attempt to remove baby from hospital occurs), pyrotechnic firing systems, quite a few things. All regulated and requiring approval. At least in the US...
 

Papabravo

Joined Feb 24, 2006
14,655
The easiest way to make a perfect sine wave is buy a signal generator. yes but it is expensive.
Breaking down a complex circuit into simple circuits has the advantage of being able to move forward.
It is common to mix two frequencies. It is common to use a filter. It is also common to avoid circuits
that look complicated so that the symbol for a mixer is repressed. A sort of complex avoidance.
A truly dizzying intellect. My head is still spinning. LOL
 

MisterBill2

Joined Jan 23, 2018
7,234
Older cordless phones used this band, also baby monitors and some wireless microphones. Or it may be for modulating some optical stuff as part of an experimental rig.
 

WBahn

Joined Mar 31, 2012
26,272
Used for RC toys, anti-theft hospital baby bracelets!?! (automatically locks down doors if an attempt to remove baby from hospital occurs), pyrotechnic firing systems, quite a few things. All regulated and requiring approval. At least in the US...
Just because you want to operate in an ISM band does not mean that you require licensing or approval. It is extremely common to operate in these bands as an unlicensed intentional emitter pursuant to Part 15 as long as you accept and abide by the limitations specified.
 

Papabravo

Joined Feb 24, 2006
14,655
From the movie script 'The princess bride'
The charecter Vizzini who has a severely dysphoric manic personality engages in a battle of wits with the man in black
ending in a match to see who will pick the poisoned wine makes the famous line as valiant and debonair 'truly a dizzying intellect'
so as to liken me to the dead villain maniac. I am not good at writing in a forum of above average writers. So in that I accept defeat. I find myself apologizing often because of bad timing in touching on someone's sensitive ordeal not intentionally wanting any confrontation at all.
The Vizzini character probably cannot remedy the embarrassing lack of emotional intelligence when I am functioning from the visual part of my brain while I am deep into a world of my own electrodynamics when writing. Thanks for trying.
Yes I am a "Princess Bride" fan, and remember most of the memes from the film.
I actually meant it as a compliment, since it reminded me of the "stream of consciousness" style of prose.

A literary style in which a character's thoughts, feelings, and reactions are depicted in a continuous flow uninterrupted by objective description or conventional dialogue. James Joyce, Virginia Woolf, and Marcel Proust are among its notable early exponents.

Especially Proust, in the original French, which I had to struggle with in my fourth year of taking the language. A distinguishing feature of the language is numerous verb forms and tenses, which can be a challenge to follow.
 

Thread Starter

Vindhyachal Takniki

Joined Nov 3, 2014
562
1. Trying to make a blood bag sealer which use RF at 40.68Mhz to seal tubes.

2. This ckt has RFin of 40.68Mhz, so need to select right sine wave clock source, then this ckt will beused as amplifer section: https://www.digikey.in/product-detail/en/nxp-usa-inc/MRF101AN-40MHZ/568-14755-ND/9749135

3. So trying to find right sine wave RF source for it , one I found here: https://www.digikey.com/en/products/detail/crystek-corporation/CRBSCS-01-50.000/4741142 

Sent mail to this company whether 40.68Mhz they can also make, waiting for their reply.


4. ckt in (2), seems to class C amplier only.

5. Any other cheaper RF source sine wave? ANother I found is company Rakon.
 

MisterBill2

Joined Jan 23, 2018
7,234
With most radio transmitters the output to the antenna is made into a much purer sine wave by the use of resonant tuned circuits. And you will find that amplifying a sine wave is the very least efficient method of amplifying. Look up the applications of class "C" amplifiers and see that all of the legal ones use adequate filtering to deliver a pure wave form.
One more question relates to the frequency. Most ultrasonic sealing is done at much lower frequencies, such as 40 Kilohertz. Ultrasonic heating of plastics is a quite mature technology, so lots of information is available.
 
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