[Johnson] DO NOT Solid State the Power Supply in your Ranger!!

[William Feldmann]

Hi All,

This subject seems to be very contriversial but
interesting.  Some tube power supplies I solid state
and others I feel it's better to leave alone.

I feel it's better not to solid state power supplies
in receivers and low level exciter stage B+ for
transmitters.  It just isn't worth the trouble and my
cause problems.  My reason is many of these supplies
will tend to raise in voltage when solid stated. 
Since many of these radios were also designed for
lowed than today's line voltage the solid stating just
adds to the problem. I've noticed higher than
specified low B+ voltage in my Viking 2 because of my
high line voltage so have left the low B+ rectifier
tube alone.

Also I am a little worried about the rapid inrush of
high voltage on tubes before their cathodes have
heated but this subject is contriversial.

But last in most cases the gain is not worth the
troube of solid stating these low B+ supplies because
the rectifier tubes seem to never fail and if they do
their replacement cost is low in most cases.

However the high B+ in many transmitters is a
different story.  In many transmitters like the
Valiant, and Collins 32V series the 5V filiment demand
for the HV tube rectifies put a heavy load on the
filiment transformer.  In my Valiant and 32V3 the HV
5R4 rectifier filiment supply places a high load on
the LV transformers which are tending to have this
winding fail resulting in an expensive replacement of
the transformer.  Therefore in my 32V3, Viking 2,
516F2 Collins supplies and Valiant I have my HV B+
supply solid stated for these supplies to relieve the
load on the LV transformer.  On the 32V3 I'm using
comercial IR plug in solid state units and the
Johnsons home brew plug in rectifier modules.

My plate voltage is a little higher than stock with
these solid state units, but I feel these transmitters
have suffient head room in their design to not have a
problem.  However, in the Valiant I had the four 350pf
fixed capacitance low band plate caps fail but I blame
that on aging of them or poor components to start with
and replaced them with higher quality ones.  Also my
Valiant was impossible to run on its side when trouble
shooting using the stock 866 mecury rectifiers so I
solid stated its HV supply from the start when
modifying its audio circuit.

Also if a transmitter is being operated properly, the
high B+ for the final and modulator would only be
turned on after the final cathodes have had time to
heat up after the non solid state low B+ supply has
come up to voltage.  This will solve any inrush
problem on cold cathodes or filiments of the final or
modulator tubes.

If I was to have a bad heat problem with a receivers
or exciters low B+ supply and the voltage was way too
high and I considered solid stating its supply, I
would consider using a Zener diode of sufficient watt
rating to drop the B+ voltage back to the stock
voltage and mount it where it could safely disapate
the heat load.

Anyway that's my two cents worth and hope I havn't
confused things more, but I feel some supplies should
definately be solid stated and others left alone.

Bill N6PY

--- Glen Zook <gzook at yahoo.com> wrote:

> All of the Heath SB-Line which is tube type design
> have solid-state power supplies and there are no
> problems with them!
> 
> I have almost all of the original tubes in my Heath
> SB-110A transceiver and the HP-23 power supply is
> definitely solid-state.  That rig is over 30 years
> old
> and is still going strong on 6 meter SSB.  Both the
> B+
> and B++ are applied when the rig is turned on.
> 
> The same thing with my Heath SB-301 and SB-401.  The
> internal power supplies are solid-state.  The old
> RCA
> commercial two-way FM units used the rapid heating
> tubes on transmit (the filaments had to go from off
> to
> on before transmitting) and the high voltage was
> applied to the plates immediately.  Again, no
> problems!
> 
> The Collins PM-2 power supply that was designed to
> use
> with the KWM-2 series is solid-state.  Again, no
> problems.
> 
> And so on.  The main things that are affected are
> the
> capacitors that may get a "burst" of higher voltage
> than they were designed for.  But, as for tube
> damage
> I have never seen any.
> 
> Glen, K9STH
> 
> 
> --- Sherrill Watkins
> <Sherrill.Watkins at dgs.virginia.gov> wrote:
> 
> Dear Ross: Consider yourself lucky! My Drake TR-4C
> has
> solid state power supply and will seriously weaken
> many of the tubes in about 12 to 18 months. Of
> course,
> the number of on-off cycle times has a lot to do
> with this.
> 
> =====
> Glen, K9STH
> 
> Web sites
> 
> http://home.comcast.net/~k9sth
> http://home.comcast.net/~zcomco
> 
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