CONFESSION TIME: this project has gone to the bottom of the pile at the moment (Jan 2014) because of my poor health and too many other ideas and projects.
Completed so far:
Still to breadboard:
Progress next week will be nil as my grandson is coming to stay over half term, so little or no ham radio until after he goes home.
Yes, you read it correctly: a simple sideband (not single sideband) rig for 10m (28MHz). By simple I mean of course a double sideband supressed carrier design. This has been a project idea for too long, so now is the time to create this. What I have in mind is a simple, small rig to use from home or out portable to work local SSB stations and the occasional DX when conditions are favourable. As with many of my projects, this is a "work in progress", so come back regularly to see how this develops. Already I have breakdboarded many of the subsystems needed, so putting these ideas together should not be difficult.
For the receiver, simple approaches such as the NE602 integrated IC mixer is adequate for the intended use: most stations that will be worked will be using at least 10W, often 100W, so that sensitivity does not have to be fantastic, just adequate. Also, the IM2/IM3 performance of the NE602, although not fantastic, is fine for such a simple radio, especially if the input filtering is reasonable.
The advantage of the DSB approach is the design simplicity with no need for expensive SSB filtering. The downside is the waste of power in the unwanted sideband and the risk of some LSB interference to adjacent channel stations. In a later version, a phasing design may be considered to attenuate the unwanted sideband by around 20-30dB. Another problem is tha receiving another DSB signal can be difficult, although not impossible.
A single balanced diode mixer followed by 2-3 stages of gain (2N3904), with either an IRF510 FET, 2N3866 or CB type bipolar PA.
Use of T37-6 (yellow) toroids for all tuned circuit inductors (small and self screened).
Discrete design using 2N3904 transistors.
Speech clipper/processor and LPF to increase "punch" with the QRP output without splatter.
Mixer/VFO with 32MHz crystal oscillator with 3.4-3.6MHz VFO. Could be based around an NE602. Stable enough for (short duration) sideband QSOs.
NE602 RFamp/mixer with 3kHz passive low pass filter and LM386 AF amplifier.
10m DSB transmitter - note that one of the diodes in the mixer of this design is the wrong way around.
28MHz 3 transistor DSB transceiver - a superbly elegant simple circuit from Japan. 28MHz DSB rig from 7K1CPT shows a photo of the completed little rig.
10m DSB QRP transmitter with VFO - a design using NE602 and SBL1 mixers.
Transceiver DSB 28MHz - from F6FEO
JF1OZL's DSB transmitter for 21MHz - simple design based around a TA7320 IC.
MFJ-9410 10m SSB transceiver - handbook
Tenner 10m QRP CW transceiver - my own circuit described elsewhere on this site
NB6M 10m CW transceiver - built Manhatten style.
The Wee Willy DSB transceiver - built around NE602s (very simple design)