[Boatanchors] T-195 DC supply

[WF2U]

Dave,

Some later versions and rebuilds of the T-195 utilized blowers with 400Hz
motors instead of 24 VDC motors, and used individual inverter circuits
mounted on the blower itself. This arrangement seems to be somewhat more
efficient than the straight DC motor, and it doesn't require brush
maintenance. They also don't have high starting current.

I'm surprised you have dynamotors instead of the solid-state inverter power
supplies. Usually in units with the AC blowers you'd find the solid-state
inverters also (although I have one T-195 that had the solid-state
low-voltage power supply installed while the high voltage dynamotor supply
was there and not the solid-state one.
These solid state inverters are direct replacements for the dynamotors, they
fit and install exactly like the dynamotors and have the same connections.
As far as I know, Barans Surplus and Fair Radio had NOS solid-state supplies
for the T-195. A few years ago I bought a couple to keep as spares.

Using the solid state power supplies instead of the dynamotors makes a big
difference in power requirement:
I use a 24V 50A to power it up, but I have to connect 2 car batteries in
series for 24 V and connect them in parallel with the supply as the starting
current surge is much higher than the power supply capacity and the
dynamotors almost stall out.
The steady-state current draw is around 47A.

My T-195A with all solid-state inverters and blowers is powered by a small
24V 35A switching power supply (military surplus Lambda, completely RFI
free) and it runs cool without any startup surge. My R-392 is also connected
to the same power supply.

I guess if you want to build an external power supply, it's possible, but
not without drilling a hole in the case to route the cable/s from the
external power supply...

Fair Radio has the manuals for the T-195 and the supplement for the -A model
which is the all solid-state inverter and blower model.

73, Meir WF2U
Landrum, SC



> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net
> [mailto:boatanchors-bounces at mailman.qth.net]On Behalf Of Dave Maples
> Sent: Sunday, July 16, 2006 9:47 PM
> To: boatanchor
> Subject: [Boatanchors] T-195 DC supply
>
>
> Boatanchor drivers: I have begun digging into a T-195.  This one
> appears to
> have both dynamotors, yet has a pair of transistors mounted on a
> fan bracket
> at the front left top of the chassis.  I have several questions:
>
> a. Does anyone have documentation on the transistor arrangement?
>
> b. Is there some reason (other than faithfulness to the original
> design) why
> I couldn't use standard power supplies with this beast and get
> out of having
> to produce 24 VDC at 50 amperes or so?  It would seem to me to make a lot
> more sense to skip using the dynamotors...
>
> c. Assuming I stick with the dynamotors, what suggestions do you have on
> obtaining the large 24 VDC current required (other than  storage
> batteries)...
>
> Thanks to all.
>
> Dave WB4FUR
>
>
>
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