FAQ
TL;DR: Need a fixed 45 MHz sine source? Beware modules that output square waves with 4 ns edges; “square wave” parts need filtering. “Google/Bing/Yahoo can be your friend.” [Elektroda, Steve Lawson, post #21669494]
Why it matters: This FAQ shows quick, safe paths to a clean 45 MHz signal and how to avoid common pitfalls. It’s for RF hobbyists and engineers asking “what’s the best 45 MHz oscillator schematic or part?”
Quick Facts
- Requirement: fixed 45 MHz sine wave oscillator as stated by the original poster. [Elektroda, Sajed Rakhshani, post #21669484]
- Fast win: tiny canned oscillators cost about a dollar (US) at major distributors. [Elektroda, Mark Nelson, post #21669487]
- Define upfront: stability, output level, supply voltage, temp range, current limit. [Elektroda, Mark Nelson, post #21669487]
- CSX‑750P concern: square‑wave output with ~4 ns edges; programming unclear. [Elektroda, Steve Lawson, post #21669494]
- Share designs privately: use forum Private Message; emails are hidden for safety. [Elektroda, Nick Cholas, post #21669490]
What’s the simplest way to get a fixed 45 MHz signal fast?
Buy a low-cost canned oscillator from a reputable distributor. These modules are tiny, stable, and around a dollar. Define your needed logic level and supply, then choose the matching part number. If you require a sine output, add filtering or select a sine‑friendly solution. “Google/Bing/Yahoo can be your friend.” [Elektroda, Mark Nelson, post #21669487]
Is the Citizen CSX‑750P suitable for a 45 MHz sine wave output?
It appears to output a square wave with about 4 ns rise/fall times, and the programming method is not evident from the datasheet referenced. For a sine requirement, plan on a filter or pick another oscillator that specifies sine output. [Elektroda, Steve Lawson, post #21669494]
How do I turn a 45 MHz square wave into a near‑sine wave?
Use a narrow band‑pass or low‑pass filter centered at 45 MHz to suppress harmonics from the square wave output noted for some modules. Follow with a buffer to maintain load isolation. This approach addresses the stated square‑wave behavior. [Elektroda, Steve Lawson, post #21669494]
What requirements should I define before picking or building the oscillator?
Decide if it’s fixed or variable, frequency and amplitude stability, output power, supply voltage, operating temperature range, and maximum current. Clear specs help you choose between a canned oscillator and a discrete LC design. [Elektroda, Mark Nelson, post #21669487]
Can someone email me a 45 MHz circuit from the forum?
Use the forum’s Private Message system rather than posting emails. The platform hides emails for safety, and moderators encourage PM for sharing details or files. [Elektroda, Nick Cholas, post #21669490]
How do I contact a member privately to get a schematic?
- Click the member’s name above their reply.
- Click the CONTACT button on their profile.
- Send your message or request the file link there. [Elektroda, Steve Lawson, post #21669488]
Are .doc attachments safe for circuit schematics?
Avoid .doc files due to macro risks. Prefer GIF, PNG, or JPG for images, and use PDFs cautiously. This reduces exposure to malicious content while reviewing shared circuits. [Elektroda, Steve Lawson, post #21669496]
I saw a post offering circuits from 1–50 MHz. Is that relevant?
Yes. A ham operator offered to share a frequency generator covering 1–50 MHz, which includes 45 MHz. Request details via Private Message rather than public email. [Elektroda, Shubham, post #21669485]
What’s an easy mistake when selecting a 45 MHz ‘programmable’ crystal or oscillator?
Assuming you can program frequency yourself. A user and others questioned how a suggested part is programmed. If the datasheet lacks a programming interface, it may require factory programming. Verify before purchase. [Elektroda, Sajed Rakhshani, post #21669495]
What if I just need a quick, clean lab reference at 45 MHz?
Pick a fixed‑frequency oscillator can and follow it with a simple filter to meet sine purity needs. Define output level and stability first, then order a part matching those specs from a known distributor. [Elektroda, Mark Nelson, post #21669487]
How do moderators handle spam or unsafe sharing in threads?
Moderators remove spam and ask users to keep contact via PM for safety. If you see suspicious posts or exposed emails, report them; they act quickly. [Elektroda, Nick Cholas, post #21669489]
Why might my ‘sine’ build still look square on the scope?
Some oscillators output fast‑edge square waves by design. Without a proper filter and load matching, harmonics remain, and the waveform stays squarish even at 45 MHz. Add filtering and buffering. [Elektroda, Steve Lawson, post #21669494]
Should I build an LC oscillator or buy a module for 45 MHz?
If you value speed and stability, buy a canned oscillator. If you want learning or custom specs, build an LC design after fixing your requirements for stability, output, and supply. [Elektroda, Mark Nelson, post #21669487]
What exactly is a ‘canned oscillator’?
It’s a small, sealed oscillator module that outputs a fixed frequency when powered. In the thread, they’re noted as tiny, stable, and inexpensive from mainstream distributors. [Elektroda, Mark Nelson, post #21669487]
Edge case: what happens if I need a sine output but buy a logic‑level oscillator?
You’ll get a square wave with fast edges (e.g., ~4 ns). Without a filter, spurs and harmonics can violate adjacent‑channel limits or degrade mixers. Plan a filter stage. [Elektroda, Steve Lawson, post #21669494]
