Don is a
founding member of The James Millen Society
and has been interested in Millen equipment
since the early 1990's. Originally the society
webpage was part of Don's personal website and
was simply called "The Millen Page".
Pictured above shows
Don's personal Millen setup. In the rack
assembly from top to bottom we start with a
90903 scope used as a transmitter modulation
monitor. Immediately below is the 90801
transmitter proceeding to the 90831 modulator.
The lower half of the rack contains two DC
power supplies. The upper supply is for
regulated low voltage plate requirements and
is set for +250 VDC. This supply also provides
all the negative bias voltages required by the
transmitter/modulator combination. Although at
first glance it appears to be a Millen power
supply, it is not! This supply started life as
a Lambda commercial 200-325VDC 100mA regulated
vacuum tube unit. The logo plate on the front
was created on transparent sticker material
using a laser printer. The sticker was applied
to a bare piece of aluminum plate which
provides the same appearance of the reverse
printed logo plates used by Millen. This
supply originally provided a high current AC
filament voltage. However that transformer
output was reverse feed into another filament
transformer, rectified and regulated to
provide all the necessary negative bias
voltages. In addition, a high voltage sensing
circuit was added that disables the 250VDC
output until the main transmitter/modulator
high voltage (600VDC) becomes active. The
lower unit in the rack is a Millen 90281 High
Voltage power supply. It provides the
aforementioned 600VDC. In the current
configuration the plate switch on the 281
supply is all that is required to switch the
setup between transmit and receive. Including
receiver muting and remote activation of the
transmitter VFO. "True vintage push-to-talk or
is that switch-to-talk."
Directly to the right
of the transmitter rack is a National HRO-5TA1
receiver. Although technically not a
Millen-era receiver, as it was manufactured in
the 1946/47 time frame or nearly seven years
after Millen left National, it retains the
look and basic circuit architecture of the
earlier HRO's. The 5TA1 version is the last of
the black HRO receivers and was soon afterward
replaced by the less famous HRO-7 which still
used the same basic design but began using
miniature tubes. This HRO-5TA1 is in almost
perfect original condition, including tube ID
stamping on the gray painted chassis. The only
non-original items are being some of his coil
units are from earlier series HRO's.
Directly on top the
receiver is a Millen 90711 VFO. Probably one
of the best VFO's ever manufactured! Accurate,
stable and it can not be damaged even with a
direct short circuit of it output. Since the
VFO's output is designed to drive low
impedances many users have connected it up
directly to an antenna and made contacts.
Above the VFO is the matching speaker for the
HRO receiver. Not shown in the picture, but
placed directly on top of the speaker, is a
Millen 92101 antenna preamplifier which is
used for 10 meter operations. The preamplifier
is mentioned as it was the first Millen piece
Don aquired.
Don has many other
items in his Millen collection, many pictured
elsewhere on this site, including his rare and
much sought after DFP-201 prototype receiver.
For further personal information about Don you
can check out his webpage.
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