(4) 10-Meter 28.3046 MHz Crystal Controlled QRP TRANSMITTERS for NOVICES

Description

Novice / Technician 10 Meter QRP Transmitter or Wireless Alarm
0909
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Price is for (4) pcs
Very Tight
Frequency Spread < 200 Hz between units
Full Epson SG51KT Datasheet:
https://linearparts.com/documents/sg-51kt.pdf
Epson SG51KT Catalog Datasheet:
https://linearparts.com/documents/sg-51kt-cat.pdf
Amateur Radio HAMs, get a 10-Meter QRP NET on the air FAST and SIMPLE with these self-contained low-power "transmitters".
These are 're-purposed' clock oscillators in a DIP-14 size package. The nominal 28.3046 MHz frequency falls nicely inside the Novice / Technician segment of the 10-Meter band (28.0 to 28.5 MHz).
Elmers, try adding
realism
to code practice sessions by literally
going 'on-the-air' while teaching real life NET operating skills!
Place a single radio in the classroom, and let a handful of students "call" and communicate with each other using only their CW skills. No talking allowed. Standby for break-ins. This can be a captivating training aid.
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 linked example below, for MCW (Modulated CW). Choose different values of resistors and capacitors for different tones.
Here's a sample MCW Mode Schematic:
https://linearparts.com/images/SG51-MCW-QRP-SCH.gif
PRECISION - UNITS SORTED by FREQUENCY
All (4) are well within the Novice/Tech band and can be heard without retuning the receiver. This set has a high to low frequency spread of less than 200 Hz. Although the data sheet claims a much wider +/- 100 ppm frequency stability, these were 100% tested and sorted to achieve this very tight grouping. The average frequency of the set is within 1 KHz of the nominal 28.3046 MHz. (Note: That is not an adjustment screw in the corner, just part of the molding.)
EXTREMELY SIMPLE WIRING
For CW Mode, just ground pin 7, connect a LPF and antenna to pin 8 and key +5 VDC to pin 14 and you're on the air. (Add a 0.001µF bypass directly across pins 7 & 14 for improved oscillator stability.) Can't get any simpler!
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 took a QRP Xmtr w/LPF Assembly (
https://linearparts.com/images/qrp-lpf-a.jpg
) and GPS tracker on the road. I grounded pin 7 to the car and draped an antenna wire over the seat. As the crow flies, it was still readable over 1½ miles away on a short wave receiver connected to a roof level vertical. Imagine what it will do when you connect it to your beam!
The output is a square wave and a Low Pass Filter (
https://linearparts.com/images/10M-LPF.jpg
) will suppress harmonic radiation. Even harmonics are negligible and even without a filter, the 3rd harmonic (within TV broadcast channel 6) is about 10 dB down before adding the suppression from the antenna mis-match for that 3
x
F frequency. Check our other listings for the 0.33 uH coils (
https://linearparts.com/images/0r33uHa.jpg
) wound on polypropylene forms, with tinned PCB length leads. Alternatively, there are Air Coil Inductance Calculators on the internet to 'roll your own'. We do not stock the capacitors but recommend silver micas.
Note: The Fc of my example was chosen to be sufficiently far enough away from the fundamental operating frequency so part tolerances would not be critical. However, this Low Pass Filter (
https://linearparts.com/images/10M-LPF.jpg
) is easily scalable so you can shift the operating frequency by changing the component values in inverse proportion to the frequency ratio. Example: To change the cutoff frequency (Fc) from 33 to 22 MHz, simply increase the component values by the ratio of 33/22 or 1.5:1. The coils required for 22 MHz will thus be 0.50 uH and similarly the caps will be 150/270/150 pF.
WIRELESS ALARMS ANYWHERE
Wire a door, gate, motion sensor, pool level detector, thermostat -- anything that can switch 5 Volts. Use 4 AAA's and a diode to drop the voltage to about 5.5V. For short distances, an antenna is not needed. A stable receiver or scanner can cover the perimeter of your yard. Carrier mode is the simplest method. A simple 555 oscillator, such as the one shown in the MCW Schematic link above, will modulate the transmitter if you prefer a tone. Different resistors and capacitors will produce different tones for easy identification of different monitoring/alarm stations. For another twist, replace the timing resistor with a thermistor to make a temperature telemetry transmitter.
Other possibilities:
10M Fox Hunt
Beacon
Model Rocketry
Telemetry
Add a divide by 2 IC* circuit for a 20 Meter HAM band output.
Add a divide by 4 IC* circuit for a 40 Meter HAM band output.
Add a divide by 8 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, 20, 6 Meter and other 10 Meter versions available.
Check our other auctions or e-Mail us.
Retail price - .45 each ........ and that's
unsorted
!
Note: Configurations and applications vary and performance varies. Please review FCC Part 15 and Part 97 if you are not certain your particular use is in compliance. The suggestions above are not intended to promote illegal or improper use. It is the amateur's responsibility to ensure the completed transmitter is in compliance and that it's operation does not interfere with other equipment.
QN-4
*************************************
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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.