The AM Forum

http://smallwonderlabs.com/Retro-75.htm

Pretty neat! 

Small Wonder Labs makes great stuff.
I've built some of the QRP CW kits, and they are High quality, well made kits mine worked first shot off the bench which is more a testament of the kit & documentation than my building skill. 

No interest etc.  I'm just reporting on my experience with the company.

That would be great for mobile.  You could modify a 4 transistor CB leenyar for 75 meters.  Probably get a good 100 watts AM out.

C

That is really a cool little rig!  I just ordered one.  I hope he doesn't run out!

73,  Jack, W9GT

It has through the holes components too, no surface mount parts.  It should be an easy kit.

Neat looking little kit..

Might take as much as an hour to build.

I admire the design and enjoyed the schematic, especially ther crystal filter and the "plate modulator".

Lots of excitement about this little rig was expressed this weekend on the AM nets.  Bob, W9RAN suggested that Small wonder labs might want to include some xtals for additional popular AM frequencies, such as 3880 as available optional add-ons.  I think that is a great idea.  It will be fun to hear a few of these rigs on soon...even though they are in the < PW category...they should work out well for the AM nets and hamfest/AM gatherings.  Fun factor should be high.

73,  Jack, W9GT

Got my Small Wonders Labs 75 AM transceiver kit and put it together over the last week.  Very nice quality PC board and components.  The RF output transistor (power MOSFET) was back-ordered, but I received it in the mail Saturday and got it installed.  Finished up Sunday afternoon and got it on the air.  Wow!  Works great.  The receiver is phenomenal for something so small and relatively simple and the transmitter audio seems to be very good from reports that I received.  Already had several contacts and all said that it sounds great for such low power.  I need to finish things up and complete installing it in a metal case with nice connectors and controls...in contrast to the present clip-leaded monstrosity on the bench top.

It works fine with an FT-243 xtal that I had for 3880 as well as the 3885 rock that comes with it.  I'm going to install a panel mounted xtal socket, so I can use other xtals conveniently.  A VFO of some sort would now be a welcome addition, as well as some sort of noise limiter for the rcvr.  That was the only problem that I noticed....band was very noisy and no way to deal with or reduce noise.  Sensitivity and selectivity, however, are very good.  All in all...$65 bucks well spent and lots of fun!

Now I need to come-up with a little amplifier to go QRO??? with 20 watts or so HI HI FB OM.

73,  Jack, W9GT

I am still waiting for mine to arrive. I've got a Nor-Cal FCC-1 vfo that I plan on using with it. I think this will be a fun little project!
Now when is the mailman going to get here?

Phil

Now that looks like a neat little project... I may just have to buy one for $65 and actually get on AM!

I wonder how well it would drive my 4x4-125A AB1 amp? I could remove the 7 db input t-pad and maybe change from 1:4 balun, 200 ohm swamping resistor to 1:9, 450 ohm for more grid swing 8)

It'll drive my grid-driven EFJ Courier just fine

Al

ARRL take note and put the AM chapter back into the handbook!

Anyone else building one of these rigs?  Might be fun to take them to Dayton this year.  Hopefully, I will be able to take some time this week to move mine from the bench top to its completed state (in a box).  I noticed that the NorCal FCC-1 and FCC-2 kits are on hold right now....but a digital read-out VFO would sure be a cool addition to this rig, as well as some boots to get the power up a bit.  Also...anyone got any good suggestions for adding a noise blanker of some sort to the receiver?

73,  Jack, W9GT

Tried to check into the Collins Collector net with the little Retro75 AM rig last night, but lightning static was horrendous and guys running 100 watts were having lots of problems, let alone trying to check-in with 2 watts.  I don't know if anyone heard me, but didn't get a response.  The receiver still amazes me.  I'm able to easily select between 3880 and 3885 and seem to hear just about anything that I can hear on the "big" receivers.  A noise blanker of some sort would be useful and other garnishes like an S-meter, etc. would be fun.

73,  Jack, W9GT

Mine is completed except for the final. Anyone have an idea how to connect the FCC-1/2 to this rig, where in the circuit? I've been looking for a circuit for a small amp, to boost the power up a few watts any suggestions?

Bob
wb6kwt

I received mine about a week ago, but holding on the output transistor. I'm going to hold off building until the part gets here and a few more improvement ideas gets bounced around. Some added features such as VFO tx, metering, noise reduction/limiting, and a little extra power out would make it a great portable rig for many uses. Looks like Dave has hit a home run with this one!

Phil

Oh man, I want one.  Keep hearing everyone having far too much fun with them!  Is there a case available or is that left up to the builder?  Sure would love to see a 40 meter version too.

John

Dave is planning to offer a enclosure in the future.

Bob

They look really neat.  I think I will order one.  I dont think its usefull at 2 watts. I am sure it will be a fun build.

C

I just ordered one.  Clark, don't be fooled by the 2.5 watts!  I was just in a qso ealier tonight and Jack W9GT was in there and despite an s9 noise floor, I was hearing quite a few words and in fact his carrier was heard quite robustly when I switched to sideband to check it out.  Had it been quieter, I would have had a q5 copy.

I know I will get some qso's out this little kit, mostly in the morning or afternoons when the locals are booming in with the short skip.  It'll be fun to check in to the normal 3.880 group and tell them I'm running 2.5 watts carrier from a kit I just completed. 

John, KX5JT

p.s. clark, sorry 3.870 is heavily populated with SSB stations here tonight, I could here the AMers underneath them but it would not have been pretty to try.

Her she is:


73, W9GT

Here are the innards:

73,  Jack, W9GT

Very nice Jack.  I like the case you used.  Seems like the perfect match.

Very nice Jack, I've been hearing guys talking all day about hearing you on it.

I have a different packaging idea in mind, but I got to thinking, a person could get an old CB mobile from the thrift store or garage sale, junk the guts, and have a pretty good starting point.  Mount the Retro 75 where the CB board used to be, you'd have holes for the two controls, a mic, coax connector, power connection, and a speaker.   The biggest problem would be disguising it somehow so it didn't look CB-ish anymore. but I think some paint and a wood chisel might do that job.   Can't hardly buy a mic for what the old CBs sell for.

73, Bob W9RAN

Bob,
        Siltronix (Swan) made a pretty nice looking  23 Ch. SSB mobile rig that would make a great donor enclosure if you can find one. I was thinking od mounting mine  in a Ten Tec enclosure. Room for an extra stage of amplification and home brew battery pack.

Phil

Thanks guys...sure having lots of fun with the little QRP rig.  Please excuse that big ugly FT-243 3880 xtal.  It is just one that I had on hand....so installed a socket and put it in there so I could join the fun on DX-60 net, etc.  Seems to work fine, although slightly low in freq.  I will probably get one of the miniature xtals to replace it.  I installed an SPDT 12 volt relay for real PTT using a Yaesu hand mike....it may not be necessary...but didn't know about switching directly thru the mike...easy enough to do with a cheap Radio Shack relay.  The case is one that I had around since 80's time frame....I think it came from Dick Smith Electronics (remember them?).  It was made in Spain of all places.  Just a little larger foot print than a QSL card....worked great to install the transceiver board, but not a lot of room left over.  I may install an internal speaker (very small) but the little rig drives a large bookshelf speaker to room-filling volume.  Hats off to K1SWL for a great little kit!

73,  Jack, W9GT

Kind of off topic but did you guys see the converted CBs on youtube?  They where converting cobras to 40 and 80.  Sounded nice.

C

Sorta hate to see the discussion drifting to CB stuff!  :o  Anyway...that might be a good way to house the Retro 75 AM rig.  I sure have been having fun with my little rig.  Lots of ideas for improvements and additions.  Perhaps adding an amplifier somewhat defeats the basic idea of a simple QRP rig, however, just a 10 dB jump in power would really help to be heard on the band.  Truly amazing, however, how well I have done with 2 Watts!

73,  Jack, W9GT