Sunday, July 6, 2014

20 Meter High Performance Direct Conversion Receiver & VXO Controlled 6W Transmitter

Well, I haven't been posting for a while.  My QRO rig (Yaesu FT-101ZD) has developed a problem with the VFO.  The frequency jumps around.  I have no idea what could be wrong.  My only guess is that there is a loose connection.  I suppose if it were a capacitor it would drift instead of jump.  I plan on at least pulling the board and have a look-see.  I wonder if I could get the external VFO and just bypass the internal one.

I have bought a You Kits HB-1B qrp rig from Ten Tec and am quite pleased with it.  I have made QSO all around the world with its spankin' 5W.  Last night I made contact with a station in New Zealand and received a good report.  I took it camping and had a ball operating from a park bench next to the lake.  The ticks and chiggers were there to great me....never going back there again.

My other QRP rig is the Rockmite 20 and it is a little harder to make good QSOs but I have worked coast to coast with it and yesterday morning I held a 1 hour rag chew with a fellow in Canada camping out in the boonies.

20 Meter High Performance Direct Conversion Receiver & VXO Controlled 6W Transmitter

Look in QST Apr & Dec 1978 for the article on how to build this transceiver.

I purchased this homebrew QRP rig off of ebay from its builder K1NYK.  The workmanship is very nice and I hope to have it up and running soon. Taken from the 1978 QST article it uses a VXO on the 20M band and has a direct conversion receiver (the lower PCB).  It should put out about 6-7W.  I tried the receiver but all I get is static.  This will be my first attempt at repairing a radio.  I first try to find the problem with a voltmeter.  I don't have a signal generator or rf detector and I guess I'll have to make something from plans off the internet.

I finally have accumulated all the parts for building a replica of my brother's QRP rig he designed that are posted elsewhere on this blog.  The NE602s where not that hard to find.  I've already started the project with a proto board.  I better get her done before I lose some of the parts. :)

UPDATE: July 25, 2014  A fellow ham has suggested that I clean the VFO capacitor to try and resolve the freq stability problem.  I've built and audio oscillator using a 555 timer to test the receiver and the circuit from the mixer to the phones is good.  Also I tested the transmitter and it is also good.  So I suspect the circuit leading up and including the mixer and BFO.  I'm trying to find out how to test those circuits.  I wish I had a signal generator that would do AF and RF.

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