SB-104 Driver transistors and 104 Upgrades

[Keith Rowland]

Ray:  If someone came up with a was to replace those little 6030 crabs
that are the virtually unobtainable 5 and 11-v regulators for the SB-104
and SB-104A, I would buy one for each of my 104As immediately.  They are
available from at least one source in New Jersey, but you have to buy at
least $50.00 worth of them at nearly $20.00 each, or buy even more to
get them down to about $11.00 each.

Do it!

73, Keith




Ray Mack wrote:
>
> I heard from Ron last night and he had gotten the MRF 314's from RF
> parts.  We talked at length about the relative merits of various
> options in transistors.  The 314's sound like they should work just
> fine for the following reasons:
>
> 1)  Just about any transistor that is capable of the power level (but
> without internal compensation) should work in these applications.
> Even the venerable 2N6080 series should work.
>
> 2)  They are the correct physical size.
>
> My suggestion for the MRF 412 is wrong.  It should be for the
> MRF 412A if it would fit.  The difference is that the 412 is flange
> mount and the 412A is stud mount.  Also the 412A is case 145A-10 (0.5
> inches in diameter) and the parts on the driver board are the 145A-09
> (0.380 diameter).  Ooops.
>
> I have not tried it yet but as I stated above I suspect that the
> 2N6080 series would also work as replacements since they have the same
> physical dimensions and ought to have quite adequate gain at HF.  The
> main reason for trying these is cost.
>
> Another option is to use the HF linear trainsistors that are rated for
> 28V.  These are the MRF 401 and MRF 410A.  These are the only 2 that
> come in the 145A-09 case.
>
> Stay tuned.  Putting this rig back on the air for my friend WB5NMH is
> my Christmas plant shutdown project.  I'll give the 2N6084 a try and
> check out the before and after IMD with the spectrum analyser.  Murray
> at Multi-Volti used to work at Heath and told me that these rigs were
> tough to get clean.
>
> Since parts for this rig are non-existent in some cases, I am also
> putting together some new boards to replace the voltage regulators
> (the six pin job thatis pure unobtainium) and a replacement driver and
> final board using modern transistors.  What do y'all think?  Do we
> stay stock on this rig or practical?
>
> Ray Mack
> WD5IFS
> mack at mails.imed.com
> Friendswood (Houston), TX
>
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