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Just a quick introduction - I'm David G3RYP and am currently building
the BITX20.

My usual breadboard construction method : a sheet of wood onto which
scraps of pcb are held by drawing pins - these also link the
groundplane between boards. Altogether very scruffy - but good for
making quick changes.

I've not made that many changes but am using an fet in the vfo and
toko coils rewound or t-50-6 toroids.

So far rx is working and only problems I've found is that the 50uf
cap in the collector of Q3 is definitely needed in my version -
otherwise lots of noise and not much signal. With the xtals I'm using
in the filter a 100p cap results in a nicer sound than when using a
220p.

I'm already thinking about a bit more gain and some agc but better
get on with the tx first!

Good luck to all.

David the site is mainly for the uBitx? multiband and the Bitx40 which is either VFO or "DDS" controlled so many of your comments won't make a lot of sense to those who purchased these pre stuffed boards as in SMD.? It is prolly a bit late to mention this? but? Fred at Far Circuits in US sells a Bitx board set of etched PCBs. you could possibly get him to part with the main bitx board for $15 USD. The other board is the class A power amp which can easily? be done on islanded copper clad board.? AGC can be done with the TDA7062A or AT? chips which have an AGC pin built in .. you sink it to GND with an NPN transistor to mute the chip.? one option there is found by studying the MST3 schematic on the ozQRP.com site of Leon in NSW. go to documents section (or even look at the old MST2 board under the archive documents section) Obviously 2 or four small signal diodes and a ceramic capacitor will give you AGC volts from further back in the radio for? RF agc..... That TDA is hard to get from normal suppliers , Farnell has it but it is all over the PRC ebay internet? at low prices. the TDA without the A or AT suffix does not have the mute pin.? cheers TEF

A thought occurs on a 20/40 m Bitx analogue dual band if you want to keep going . There are three parts that need switching.? RF in.? ?the clean up filters after the RF mixing and the final LPF.? those first two could potentially be done by a second ceramic RF variable capacitor for high Q? switched in by a small signal diode to ground to go to Low band. the? LPF because of the power,would generally have to be relay switched but the relay is only powerd on on one band , not both (two SPDT relays, one per filter end).? A Farhan gave? and still has a design on the internet similar to this for 40/20m transceiver? but many many relays he admits as much.? You also need to design the carrier inject osc for LSB/USB using a puller inductor and capacitor for low and variable trimmer capacitor for high. For the vfo,? you can either make a WIDELY tuning VFO with fine control via a trimmer or? use a dual gang tuning capacitor and two vfos and switch in on or other by? having an A not B an B not A power supply arrangement.? A Farhan advocated he latter method I guess beccause relay switching of a single capacitor is problematical .? He used a fet plus buffer transistors VFO design. There is no "Best IF" for this but 10M is popular as an IF frequency as it works for both 20 and 40 m and xtals are cheap and easy to find..... TEF

No, this group is for ALL of the BitX. From the group description:

"This group exists for constructors of the various BITX projects"

There are people here that have built all of the different BitX flavors. David, you're in the right place.

Vince - K8ZW.

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Michigan VHF Corp.