Category Archives: FT8

The Hermes-Lite SDR: an open source QRP transceiver based on a broadband modem chip

Note: This is a cross-post from the SWLing Post.

Many thanks to Pete (WB9FLW), who shares the following:

Don’t know if you are familiar with this project, a full blown 5 watt HF SDR Transceiver for less than $300!

No sound cards, DUC/DDC architecture.

Here’s the project description by Steve Haynal via YouTube:

The Hermes-Lite is a low-cost direct down/up conversion software defined amateur radio HF transceiver based on a broadband modem chip and the Hermes SDR project. It is entirely open source and open hardware, including the tools used for design and fabrication files. Over 100 Hermes-Lite 2.0 units have been successfully built.

The FOSSi Foundation is proud to announce Latch-Up, a conference dedicated to free and open source silicon to be held over the weekend of May 4th and 5th in Portland, Oregon, USA. Latch-Up: a weekend of presentations and networking for the open source digital design community, much like its European sister conference ORConf. Produced by NDV.

Click here to view this presentation on YouTube.

Fascinating! Thank you for sharing, Pete!

FT8 transceiver kit: CR Kits taking orders

The CR Kits DSB Transceiver prototype (Source: CR Kits)

Many thanks to Pete (WB9FLW) who writes:

Thomas,
Adam of CR Kits is now taking orders for his FT8 Transceiver Kit and the price is very reasonable.

From Adam at CR Kits:

FT8 transceiver kit

Folks,
I start to take email order now. The introductory price is 39 USD for kit including shipping to worldwide. As in the introductory period, you will get audio cable options for free. The earliest possible shipment date is now improved to May 13.

You can directly PayPal to [email protected] and let me know 40m or 20m (80m not ready yet). I will ship based on the sequence of receiving your payment. I may delay shipment for one week or two due to workload.

This is the spec so far:

Summary: Crystal controlled single frequency DSB transceiver for 20m (14.074MHz), 40m (7.074MHz) or 80m (3.573MHz), other frequencies could be added per requestPower supply: 10-14V DC regulated power supply or battery pack, 12V is recommended, center positive, reverse polarity protection availableCurrent consumption in RX: about 15mA at 12VCurrent consumption in TX: about 300mA at 12VRF output: about 1W for 40m band at 12V, and a bit less for 20m bandSpurious suppression: no worse than -50dBcAntenna connector: BNC connector, 50 ohmAudio in connector: 3.5mm mono, at least 600mV to activate VOX, connects to headphone connector at PC sound card, no dedicated PTT connector is requiredAudio out connector: 3.5mm mono, connects to microphone connector at PC sound cardAmber LED: TX statusGreen LED: RX statusFrequency accuracy: -600 Hz ~ + 200 HzFrequency stability: Okay for FT8 mode per test. If the optional heater resistor R20* is added, after warm up, long term frequency stability in 10 min will be improved at the cost of acceptable short term frequency stability sacrifice in 30 sec.
Thanks, Adam

Click here to check out the FT8 DSB Transceiver via CR Kits.

New digital mode: Joe Taylor (K1JT) has announced FT4

(Source: Southgate ARC)

Joe Taylor K1JT has announced a new digital mode, FT4, which is 2.5 times faster than FT8 

FT4 is an experimental digital mode designed specifically for radio contesting.  Like FT8, it uses fixed-length transmissions, structured messages with formats optimized for minimal QSOs, and strong forward error correction.  T/R sequences are 6 seconds long, so FT4 is 2.5 × faster than FT8 and about the same speed as RTTY for radio contesting.  

FT4 can work with signals 10 dB weaker than needed for RTTY, while using much less bandwidth.

FT4 message formats are the same as those in FT8 and encoded with the same (174,91) low-density parity check code.  Transmissions last for 4.48 s, compared to 12.64 s for FT8.  Modulation uses 4-tone frequency-shift keying at approximately 23.4 baud, with tones separated by the baud rate.  The occupied  bandwidth (that containing 99% of transmitted power) is 90 Hz

Further information on FT4 is at  
http://physics.princeton.edu/pulsar/k1jt/FT4_Protocol.pdf

Ham Radio Digital Modes: Joe Taylor talks FT8 and introduces FT4

Many thanks to Pete Eaton (WB9FLW) who shares the following note and video:

Here is a You Tube Video of a presentation given by Joe Taylor last night at the Fair Lawn ARC Club Meeting on FT8 & Beyond an introduction to FT4.

Click here to view on YouTube.

Thank you for the tip, Pete!  FT4 looks like a fascinating iteration of the popular FT8 mode.

A Simple and Low Cost FT8 Transceiver

Many thanks to Pete (WB9FLW) who writes:

Adam Rong BD6CR has designed a simple DSB Transceiver for FT8. Crystals are available for 7.074 MHz. and 14.070 MHz (which can be “pulled” with a trimmer to 14.074 MHz).

Using only 4 Transistors, 2 IC’s, 3 Toroids, 5 Diodes/LED’s and a handful of resistors and capacitors this one watt wonder will get you on the air in no time.

Click to enlarge.

One could build this on Perfboard (see above), or use Ugly/Manhattan style construction. There are no plans for a circuit board.

Adam posted this on groups.io crkit:

“I built this 7074 DSB 1-watt radio and made 6 FT8 QSO with JA stations in 15 mins last weekend. It is fun to operate by switching PTT manually to keep it simple and lower current consumption.”

For more info check out crkits groups.io.

Wow! Thank you for sharing this Pete. I’ll have to give this a go myself!