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I'm building my first radio receiver (a simple Ramsey HR-40 kit). The "Alignment" section of the instructions requires that I have some other device which I tune my receiver to. Since I have no such device I plan on buying one. The cheapest option seems to be a crystal oscillator. However, how I would use this crystal oscillator to tune the receiver isn't very clear.

I'm assuming I would want a crystal oscillator in the appropriate range (for me a 7.2MHz one should be good). But I'm not sure what I'll need to do with it and what additional parts I'll need. Will the oscillator actually emit a signal that can be picked up by the receiver? Or do I actually need to add the oscillator to the circuit somehow? And what other circuitry will I need to drive the oscillator? Thanks!

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  • \$\begingroup\$ That receiver can mix an umodulated carrier to audio, so you will hear a tone if you inject a signal in its frequency range. A common technique is a "marker generator" where you take a 4 MHz crystal and divide it down to the KHz range with a digital circuit that produces a square wave rich in harmonics. Such a circuit will couple into the receiver and produce an audible signal at its multiples, for example every 25 KHz or ever 50 KHz. Before digital displays were common, many ham transceivers had these built in, with a power switch to enable them when you wanted to check the band edges. \$\endgroup\$
    – Chris Stratton
    Commented Jul 29, 2014 at 20:35
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    \$\begingroup\$ For a single in-band frequency you might also look at sourcing a more available 7.15909 MHz (2x colorburst) crystal and oscillating it with a pair of NAND gates linearized with feedback resistors. Try to track down a copy of the ARRL handbook or similar online content. \$\endgroup\$
    – Chris Stratton
    Commented Jul 29, 2014 at 20:38
  • \$\begingroup\$ @ChrisStratton: I will get look into the ARRL handbook. Will the oscillator be physically connected to the circuit or will it just produce a radio signal that the proximity of the receiver will detect? \$\endgroup\$
    – Shiania White
    Commented Jul 30, 2014 at 2:54
  • \$\begingroup\$ If you are in a well-funded lab taking measurents, it is connected via an attenuator. If you are a ham, it is sitting beside the radio and coupling via the imperfections in shielding of each. \$\endgroup\$
    – Chris Stratton
    Commented Jul 30, 2014 at 3:00

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"...Will the oscillator actually emit a signal that can be picked up by the receiver?" Yes. You don't even need a frequency marker, if you can hear the signals that you want.

You should just read on in the instruction manual. It seems quite clear and my answer would just repeat what the manual already says. Here is a quote.

Alignment: Turn on whatever reference signal source you plan to use. This can be a regular transceiver keying a few milliwatts into a dummy load, a crystal oscillator or a signal generator. Or, you can look for a known signal that you have tuned in on another receiver. If you are without any reference signal whatsoever but have a reasonable antenna , you can use your familiarity with the 40-meter band to make a rough alignment of the receiver.If Ham radio and 40 meters are new to you, here’s a rough idea of what you can expect to hear on this busy band. 7.00 - 7.08 MHz - CW, most of it is fairly fast 7.08 - 7.15 MHz - Teletype (RTTY) and digital operation 7.10 - 7.20 MHz - SSB voice, many different languages 7.20 - 7.35 MHz - general SSB voice operation

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