Introduction

 to the

Arizona ScQRPions

Fort Tuthill 80m Transceiver (FT80)

 

The Arizona ScQRPions are delighted to formally announce a new 80m QRP CW transceiver kit for 2010!  This new transceiver is the creation of Dan Tayloe (N7VE) and kitted by the ScQRPions with invaluable assistance from Doug Hendricks (KI6DS) of QRPKITS.COM. 

 

 

Above is the transceiver in a beautiful homebrew circuit board box with a digital frequency dial and keyer added by Ken, WA4MNT.

 

Ft_Tuthill_80_9

 

This is the standard transceiver in a very nice commercial box by Jerry, W5JH.  A battery holder is also contained within the lid.

 

Doug approached the ScQRPions with an idea for the new kit soon after our decision nearly two years ago to return to our original Fort Tuthill site.  The purpose was to support our return and help continue our forums.  Doug arranged for Dan Tayloe (N7VE) to do the design work and has permitted the ScQRPions to produce the kit.  In addition to the 80m kit, versions for 40m and 160m will be available later in the year from QRPKITS.  Watch for them at Dayton!  The 160m version is already on the air.

 

The first public rumblings of this kit were seen in August 2009 at the Fort Tuthill, Arizona, CactusCon 2009 in a presentation by Dan on the design and use of distributed RC filters in receivers.  The transceiver had its beginnings as the Unichip transceiver in one of the major ham magazines some years ago.

 

The present design doesn’t even resemble its simple origin as Dan includes one of his low noise mixers and distributed filtering throughout the transceiver to produce one of the best sounding DC receivers anywhere.  The transmitter produces a clean 2.5 watts output using a pair of BS-170 FETs as the final amplifier.  The transceiver has a rock stable VFO covering up to 80KHz centered where you want it. 

 

Specifications:   

 

Receiver

 

* DC receiver (not a superhet)

* Current Drain:  Approximately 28 ma @ 12v. 

* Supply voltage range:  12 to 13.8v

* Receiver bandwidth: ~700 Hz.

Five pole R/C active filter provides the selectivity, nominally

3 dB down at 1 KHz, 40 dB down at ~2 KHz, 100 dB down at ~8 KHz

* MDS receiver sensitivity:  -116 dBM in a 700 Hz bandwidth

* Third order distortion (IP3): +25 dBm (10 KHz away limited by the R/C filter response)

* Blocking Dynamic Range (BDR): ~100 db (10 KHz away limited by the R/C filter response)

 

Transmitter

 

* Power Output adjustable from 0.1 to 2.5w (12v)

* Current consumption 2.5w output power using 12v and 670 mA current drain

* All output harmonics less than -49 dB down

* Transmitter is set up for a straight key input

 

Features: 

 

* RIT ~ +/- 1200 Hz allows user to move from USB to LSB to allow moving away from an interfering signal on the opposite sideband.

* Tuning range:  50 KHz segment of the 80m CW band.  This can be extended to 80 KHz by using the other half of the main tuning capacitor.

* Spot switch to allow setting precise TX spotting.  Spotting mode is entered via a push button.  A 800 Hz blip is sent once a second to remind the user that the rig is in the "spot" mode.

* Transmit protection - When the transmitter is left key down for more than three seconds, the transmitter goes into a "dotting" mode (33% duty cycle) to protect the finals.

* Audio limiting - The audio output has been designed to drive headphones and have been provided with diode limiting to protect the user from sudden, large signals.

* Accessory 5v output - A regulated 5v output has been provided for external accessories such as a keyer kit.

 

Pictures, schematics, board layouts, prototypes, Dan's CactusCon2009 presentation and slides, and other information is now available at the new user's group email list at http://groups.yahoo.com/group/fttuthill80.

 

The list is monitored by the designer and other highly skilled technical contributors such as Jerry (W5JH) and Ken (WA4MNT) who will be able to assist with any difficulties you may have.  Many others will become resources and join in as time goes along. 

 

The new Fort Tuthill FT-80 should be available about the end of January 2010.  All parts have been ordered and most are already in hand.  The first run is limited to 100 kits.

 

The kit includes a 3.5” x 3.5” PCB, all board mounted parts and all chassis mounted parts including main tuning capacitor and mounting hardware, volume pot, RIT pot, headphone jack, spot switch, BNC antenna jack, power jack, and straight key jack.  $50 covers virtually everything except for a case and knobs.

 

Winter is here!  This is a great time to warm up the iron and introduce yourself to the magic of 80m QRP!

 

An ordering link will be provided here when the kits are available.