DL-QRP-AG SMD-Training kit HegauSMD

Virtually every item of consumer electronics including washing machines as well as state of the art transceivers contains surface mounted devices – SMDs. Initially having been developed for thick film technology, these "mini ICs" now permeate every branch of electronics. The primary reason for the wide spread use of this technology lies in a big cut of production cost by enabling fully automated mounting and soldering. The devices‘ small sizes result in improved RF features up to the micro wave regimen. Without SMDs, most UHF-SHF-applications would be impossible.

These clear-cut advantages will lead to the extinction of traditional wired components in the near future due to decreasing demand. Those radio amateurs who still do some homebrewing should therefore get acquainted with this technology as soon as possible. The project described below is meant to constitute an introduction to SMD soldering upon completion of which a full 40m QRP transceiver can be obtained. In designing this circuit the developer has tried to strike a balance between device specifications and component count. A further decrease of the latter would have deteriorated performance. This kind of "Transceiver just for fun" really should be fun to build and should not – as is the case with so many projects – fail to work and be forgotten on the back shelf.

This small SMD transceiver is characterised by the following specifications:

- Simple direct conversion concept not requiring expensive special parts
- Variable coil – tuned VXO (offering large frequency coverage using a single quartz)
- electronic TR/RX switch, capable of full-bk
- CW sidetone
- optimised RX prefilter (attenuating potentiometer not necessary)
- Audio part’s frequency response intended for CW reception (400-1000Hz)
- good receiver sensitivity with low equivalent input noise
- 1W PA using MOSFETs (at 12V)
- operating voltage: 8-14V
- little external wiring due to all plugs & volume pot. being on the circuit board

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