1. Top view: Power Amplifier Stage and Low-Pass Filters
The PA stage consists of four push-pull modules, each comprising a pair
of Motorola MRF150 MOSFET devices. Each MRF150 is rated at Po = 150W. The amplifier thus
has a 20% safety factor, but is operated somewhat conservatively at 1 kW P.E.P (1.8 to 30
MHz) to maintain optimum IMD3 (< -30 dB relative to peak 2-tone). The PA is de-rated to
500W P.E.P. output on HF RTTY/FM (1 hr. transmit time at 100% duty
cycle), and on 6 meters.
Click here for Quadra brochure.
Download an MRF150 data sheet. Click here for detailed specifications.
Click
here for Yaesu Quadra System page.
2. Bottom view: Heatsink and Autotuner
The machined aluminum heatsink is cooled by two large muffin fans,
visible at the rear of the RF cabinet. The autotuner is a T-network, with a
tapped shunt inductor
switched via relays and two series air-variable capacitors driven by stepping motors. The
SWR matching range of the tuner is 1:3 ~ 2:1 (160m), 1:3 ~ 3:1 (all other HF bands) and
1:2 ~ 2:1 (6m). The tuner insertion loss is 0.5 dB. When enabled, the
tuner is in the signal path on both transmit and receive; it thus serves as
a tracking preselector. The tuner is cooled by a small muffin fan mounted on the tuner
shield cover (not shown).
3. Controller Board with 16-bit Processor
The controller board is the "brain" of the Quadra. It
incorporates a 16-bit micro-processor, which controls band selection, autotuner operation,
amplifier housekeeping and protective functions. Sensors in the PA stage and autotuner
send status information to the controller.
Download Bill, N4ATS'
VL-1000 CPU (Q1001) VDC Pinout Template.
Click
here for information on interfacing
the Quadra to an Icom exciter, and here for information on interfacing
the Quadra to a Yaesu FT-1000MP, MkV or
FT-2000
with complete QSK capability.Click here for
Yaesu FT-847 interfacing information. Click
here for Jerry, W4UK's universal
Quadra control interface, which offers full Quadra functionality with any
exciter. Click here
for the microHAM Band Decoder,
which also allows any exciter to control the Quadra.
Click here for
Quadra/Elecraft K3 interfacing information.
4. The VP-1000 Power Supply, top view
Inside the VP-1000 cabinet is a 2.5 kVA switching power supply, cooled
by two large muffin fans. These are visible at the rear. The mains circuit breaker is to
the left of the fans. The VP-1000 delivers 48V DC at 50A when operated on 220V mains
(reduced to 35V when the
LOW key is
pressed for 500W output.) The
acceptable mains voltage range is 100 to 235V, 50/60 Hz. RF power output is derated to
500W P.E.P. with 120V mains. Click
here for eHam Quadra reviews. Click
here for ARRL product review (ARRL members
only). Click
here
for RSGB Quadra review (courtesy VA3CR). Click
here for my Quadra mini-review.
Click here for an
ALC overshoot test.
5. Display Screenshots
Main screen, showing peak & average power, PA
drain current and SWR. The operator can toggle SWR/PA drain voltage. Click here
to download Quadra info. Click
here to view FL-7000 info, and here
for Bill, N4ATS' authoritative FL-7000 site.
Autotuner screen, showing instantaneous tuning capacitor
settings and SWR whilst tuning. You can see the capacitors rotating! Click
here for ARRL Quadra review (members
only).
Load analyzer screen, showing SWR at tuner input (dash)
and output (dot) vs. frequency. The frequency resolution is selectable. (Note:
If SWR > 3:1 at tuner output, the Quadra goes off-line. This feature protects
against damage due to antenna-system failure.)Click
here for a general discussion of solid-state HF amplifiers. Here's
why I prefer solid-state; I have a healthy fear
of
HV.
