Hi Jorge,
The component ID's should be marked on the circuit board. C1 & T90 (2 each
in bridge configuration) comprise a hybrid quadrature bridge circuit
providing +/- 45 degree phase shift at resonance (-3db each).
XL = Zo, so for 50 ohm at 1.9 mhz, L = 50 / (2*3.14*1.9) = ~4.2 uH
Both coils are wound in bifilar fashion on either side of a common core with
#16 Teflon insulated wire.
XC = 2 x Zo so at 1.9 mhz, C = 1 / (2*50*2*3.14*1.9) = .0008 or ~800 pF
The capacitance may well consist of multiple caps in parallel.
I would think that caps should be rated ~3kV or better for QRO.
Starting from the feed point corner of the bridge, the adjacent corner
(through the series inductance) produces -45 degree output which drives the
two "side antennas" in parallel. The opposite side of the bridge (through
the series capacitor from the feed point) produces +45 degree output (note
that 45-(-45)=+90 shifted from the "side" antennas) which drives the rear
antenna and the forward antenna in parallel. The forward antenna, however,
is routed through a 1:1 inverting un-un to achieve the 180 degree phase
shift on the forward antenna. The impedance of each output is transformed
by 1/4 wave, 75 ohm feed lines to match the antennas. The far side of the
bridge (opposite the feed point) is connected to a 50 ohm dummy load which
absorbs any RF resulting from unbalanced operation.
The output from the quadrature bridge & inverting un-un are, of course,
taken through a series of three DPDT relays to facilitate remote directional
switching. The relay control circuitry is protected by MOV's and RF bypass
caps.
Hope this helps you & also that your box checks out OK!
Please email me direct if you would like a copy of hand drawn schematic.
73
Matt
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jorge
Diez - CX6VM
Sent: Friday, May 23, 2014 9:07 AM
To: towertalk@contesting.com
Subject: [TowerTalk] DXE TFS4-160 circuit
Hello
I am with some friends that are helping me to test the 160 mts DXE 4SQ box
to see if is damaged by lighting.
They asked me for the circuit but is not in the manual
Anyone can help me with this?
DXE told me to send it back to USA, but I want to test it here before paying
more that it cost to send it back and forth Uruguay
Thanks
Jorge
CX6VM/CW5W
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