KIT BUILD OF THE ( LANGPORT ) KIT FORM RECEIVER
Manufacturer WALFORD ELECTRONICS
Their web site ____ http://www.users.globalnet.co.uk/~walfor
I have for some time wanted a small portable HF transceiver that I could use away from home. I already posses a YAESU FT847 which is portable, but quite frankly I am reluctant to use this set away from home due to its cost and likelyhood of damage/theft, and as most of us know the modern black box is likely to be a manufacturer only affair if repair should become necessary.
I am not new to kit building as I have assembled several in the past and also done a fair bit of homebrewing out of my junk-box ( I am building a frequency selective impedance bridge featured in the December 1999 issue of RADCOM just now ) but as anyone who has tried hombrewing knows it can be a time consuming affair especially if the circuit you are trying to assemble is a circuit idea rather than a hard and fast design ( which most junk box builds usually end up as you try to use the parts you have rather than buying new )
I dont know about others but I am reluctant to spend money on new components untill I have a design that is showing a good deal of promise.
Flicking through the latest Radcom ( April 2000 ) I came across a review of the Langport kit transceiver ( page 38 ) and decided to give it a shot, and through these web pages I will tell you how I get on.
The rig is a QRP ( 5w on tx ) design for the 80 and 20 metre bands but unlike most QRP TX,s it covers both bands almost end to end
(QRP transmitters usually are crystal controlled and have only a very limited tuning range as it is not easy to swing a crystal very far from its natural frequency of resonance )
The receiver is a superhet with a 6 MHZ intermediate frequency amplifier and has a product detector which means it can resolve SSB and CW as well as AM, it also features a audio CW filter to reduce the noise level when listening to morse transmissions, and has a built in R/T ( receive / transmit ) switch so antenna changing is not necessary, the same oscillator is used for the TX and RX so there is no worry about the receiver being on a different frequency from the transmitter
If you have only ever used black boxes then the last paragraph may seem to be stating the obvious in regard to antenna change over and the RX tracking the TX but with QRP home built rigs it is really a step back in the past where it was not unusuall to have a seperate TX and RX joined by a antenna change over unit and the receiver would have to be checked often to make sure it had not drifted from the transmit frequency
These pages will be added in sequence as I progress through the build