(5) Miniature 20-Meter QRP TRANSMITTERS - Crystal Controlled

Description

Gen, Adv, Extra Class 20 Meter QRP HAM Band Transmitter - 14.318 MHz
0725
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Price is for (5)
miniature
QRP Transmitters.
Lightweight < ¾ gram! Great for Helium Balloon experiments.
Go
CW
,
MCW
or even
AM
mode!
Datasheets:
Seiko / Epson SG-531P
https://linearparts.com/documents/sg-531p.pdf
DigiKey Catalog Page
https://linearparts.com/documents/sg-51kt-cat.pdf
Amateur Radio HAMs, get a 20 Meter QRP NET on the air FAST and EASY with these self-contained low-power transmitters.
Price is for (5) pcs.
These are clock oscillators in a DIP-8 size package. The nominal 14.318 MHz frequency falls nicely inside the upper half of the 20 Meter General HAM band (14.225 to 14.350 MHz).
If your receiver has a product detector or BFO, use these in CW (Carrier) Mode. You can identify different stations by the slight variations in frequency. If you are using an AM-only receiver, just add a simple modulator, such as the example below, for
MCW
(Modulated CW). Choose different timing resistors and capacitors for different tones. For a different twist, use a thermistor in place of the 33K resistor to transmit temperature telemetry.
SIMPLE WIRING - Standard or OE
Standard CW Mode: Just ground pin 4, connect an LPF (low pass filter) and antenna to pin 5 and key +5 VDC to pin 8 (shown below) and you're on the air. (A 0.001 µF capacitor across pins 4 & 8 will improve oscillator stability if leads are long.) Can't get any simpler!
Alternate OE keying,
https://linearparts.com/images/SG531P-QRP-OE-alt-sch.jpg
, uses the Output Enable pin 1. When pin 1 is held low through a 1 K resistor, the output at pin 5 is turned off, but the oscillator is kept running. Key +5 volts to pin 1 in this configuration for computer generated morse code.
LONG RANGE
Of course range varies widely and avid QRP'ers know that it's the antenna, antenna, antenna that is the key. But as an example, I've had 6M and 10M units on the road, using a short wire antenna draped over the car seat, reach out over 1½ miles to a receiver connected to a roof level vertical. I imagine these will perform similarly. But the real possibilities come from elevated antennas on both ends, especially beams.
AMPLITUDE MODULATION
AM operation is easy with a small audio transformer. The example to the right works well with an audio source intended to drive a speaker. Note the reversal of PRI and SEC windings. The impedances are not critical and almost anything close will work.
Optional Low Pass Filter (LPF)
The harmonics are weak, but you can construct your own filter if you experience interference with nearby equipment. (This plan is for informational purposes only. This auction does NOT include LPF parts.) The cutoff is well below the 2nd harmonic but with a wide buffer zone so loose part tolerances won't threaten clipping the fundamental frequency. The 0.66 µH air core inductors can be handmade by close-winding 15T #22 on a ¼" form. For other wire sizes and/or coil dimensions there are Air Coil Inductance Calculators on the internet to 'roll your own'.
Other applications:
20 Meter Fox Hunt
Beacon
Telemetry (at less than 1 gram, these are ideal for helium balloons)
Model Rocketry
Add a divide by 2 IC* circuit for a 40 Meter HAM band output.
Add a divide by 4 IC* circuit for a 80 Meter HAM band output.
Add a LPF and a small amp on your band of choice for a serious QRP transmitter.
* Note: a 74LS74 or equivalent binary divider is recommended.
160, 80, 40, 10, 6 and other 20 Meter versions available.
Check our other auctions or e-Mail us.
Note: Configurations and applications vary and performance varies. Please review FCC Part 15 and Part 97 if you are unsure your particular use is in compliance. The suggestions above are not intended to promote illegal or improper use. It is every amateur's responsibility to ensure their equipment is in compliance and that it does not interfere with other equipment.
Q20D-5
*************************************
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IMPORTANT: The parts we sell are categorized as new because they are unused, but many of our parts are those rare, hard-to-find, discontinued, manufacturing surplus and
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Parts from a larger OEM package may be repacked for smaller lot size orders or for more practical handling and shipping.
We strive to give full and accurate descriptions to earn your 5-Star Feedback. Any known deficiencies are listed in the detailed description. Datasheets are provided when available. Some datasheets may be close but not a perfect match because of part revisions or because they may be from a different manufacturer. If you have any questions concerning our products please email us before purchasing. Your complete satisfaction is important to us before and after the sale. Thank you.