[Lowfer] Lowfer Final Transistors.

[LEE BAHR]

Andy:

I need to clear something up.  I first heard from John, W1TAG.  He told me 
about the MPS transistors but mentioned MPS6502/MPS6652.  I think he meant 
to say MPS6602 and not MPS5602.  Looking on the internet, it appears to me 
the MPS6602 is the mirror image of the MPS6652 transistor and not a MPS5602.

Is this correct?  Am I really looking for MPS6602 and MPS6652  ???  I think 
this is correct.

The 6602 seems to be the hard one to find.  The PNP MPS6652 seems easy to 
find and available.  I am sure I'll find some in the next few days.

Right now I have all the parts except I'm waiting for my K1EL programmed 
beacon keyer chip and I have some PN2222A and PN2907A transistors to get me 
started.  Bill E Bower is building me my LITZ coil.  We both live in Houston 
and I see him from time to time, famous call sign WEB.  I saw him last 
Thursday and he is doing well.  I'm going to build the transmitter up in 
"Manhatten Construction".  I had a few Epson OSC chips programmed times 10 
for the Lyle Koehler, k0lr circuit.

Andy, I appreciate the info on the MPS transistors vs the PN transistors. 
Maybe Mike, KU4XR can come up with the part numbers for the Zetex 
transistors he thinks highly upon too.

FYI, I talk to Charlie, W5COV, call sign "CV" a lot through e-mail.  He is 
busy gathering parts for his Paraset project.  I went through that process 
awhile back.

I sure hope to have my Lowfer Beacon ready to go for the Winter Season.

Lee, w0vt




"Good luck with the new transmitter construction. I use the transistors
that John mentioned. MPS6502/MPS6652...they are definitely better than
the 2907/2222 pair. The biggest reason for the 2907/2222 combination is
probably they're easily obtainable. The MPS pair will require a little
searching on the net for a source, and possibly having to purchase from
2 different sources. But, they are worth finding in the long run.
I have not built a Class " E " final so can't give any experienced pros,
and cons, but just from all the reading I have done, it might come down
to complexity versus simplicity. The 2907/2222 setup is very simple to
construct, is very forgiving to impedance mismatches, and will easily
obtain 90% efficiency in Class " D " configuration. The Class " E "
design is not as forgiving to impedance mismatches. The construction
requires more detail to matching or you'll probably be popping the
transistor more than you would like. There are many good articles on
Class " E " transmitters on the net should you decide that you want to
go in that direction..... Again, good luck in whatever direction you
choose to go. Hope you can get one on the air soon.  73 for now :"

Andy-KU4XR