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Item:(6) 20-Meter E,A,G Class HAM QRP TRANSMITTERS

(6) 20-Meter E,A,G Class HAM QRP TRANSMITTERS

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Ended:Nov 12, 200921:00:27 PST
Bid history:0 bids
Starting bid:US $8.50
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Price:US $12.00
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Item number:350270033721
Item location:South Central, United States
Ships to:United States
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Item specifics
Application: QRP Fun  
E,A,G Class 20 Meter QRP HAM Band Transmitter - 14.318 MHz

0705

HAM Radio

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Auction is for (6) miniature QRP Transmitters.

Lightweight < ¾ gram! Great for Helium Balloon experiments.
Go CW, MCW or even AM mode!
Datasheet: Epson SG-531PT (78K PDF) Catalog Page: Epson SG-531 Cat. (21K PDF)

Click: Simplicity  Range 

Amateur Radio HAMs, get a 20 Meter QRP NET on the air FAST and SIMPLE with these self contained low-power transmitters. High bid wins the lot of (6) units.

These are clock oscillators in a DIP 8 style package. The nominal 14.318 MHz frequency falls nicely inside the upper half of the 20 Meter E,A,G 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 values of 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. (Add a 0.001µF bypass directly across pins 4 & 8 for improved oscillator stability.) Can't get any simpler!

Alternate OE keying 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. Return to top.

Return to top.

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.
Return to top.
AMPLITUDE MODULATION
AM operation is easy with a small audio transformer. (Transformers are available in our other auctions.) 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. Return to top.

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, go to Approximate Air Coil Inductance Calculator to 'roll your own'.
Other applications:
  • 20M 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, 10, 6 and other 20 Meter versions available.
Check our other auctions or e-Mail us.


Buy It Now - BONUS 2300Hz Transducers

If you are the 1st bidder and if you choose eBay's  option for this item, you will also receive, for FREE, (2) ultra miniature 2300 Hz SMT-901 Audio Transducers. These will provide a sidetone for the MCW Mode QRP Transmitter. Couple the transducer to the NE555 output pin 3 with a 10µF capacitor. The 33K and 0.01µF values shown in the schematic produce the 2300Hz design frequency. You can replace the 33K resistor with a 50K trimmer and adjust for peak audio output. These retail for $3+ each. Return to Top

Datasheet: SMT-901


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Don't wait! The BIN option is only available to the 1st bidder.
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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.

Q20D-6

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Pay only $10.00 shipping for orders of 8 or more eligible items from pbsn6040.
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Item location: South Central, United States
Shipping to: United States
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United States
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4-7 business days
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*The estimated delivery time is based on the seller's handling time, the shipping service selected, and when the seller receives cleared payment. Sellers are not responsible for shipping service transit times. Transit times may vary, particularly during peak periods.
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