Lash up Direct Conversion Receiver

[pwdrive]

Cheers Al, well it's comming along fine so far but as stated from 18 mhz up to 30 mhz is going to be a stretch I think...Not sure if it's possible but will give it a go, assuming I can extract harmonics upto 30 Mhz then so far as unwanted harmonic products go I would be delighted of I can get them down to the equivilent level of say the image frequencies you would expect to find in a SW receiver with a 450 Khz IF and fitted with a single RF Amp. To be honest it's a tall order for the higher frequencies, the 30 Mhz thing is to some extent arbitary as my 10 meter reception hear is pretty bad even when there is a lift on, we will see anyway, if that last stretch is not attainable then I will eventually finalise the design as it stands with an on board 1 Mhz osc and harmonic generator and possibly a cascode RF amp but leave provision for plugging in a VFO as another one of my projects I am working on is a valved direct conversion receiver but using a DDS/Shaft Encoder for the VFO as the osc has to be pretty stable throughout the spectrum on a DC receiver, the mixer will be either a double balanced SBL1 solid state type or a single balanced trifillar wound (home wound) feeding a couple of signal diodes in one envelope (EB91) with an AM rejection balance pot fitted, this one won't be for some time yet. Forgot to mention in the previous post that if using a sig gen as an osc source connected to the harmonicgen/amp input then tuning the harmonic tank circuit to the sig gens frequency (ie 17 Mhz for 20 meter band coverage) enables the sig gens output to be reduced to 25 mv so basically any sig gen can be used if so desired.

Lawrence.