The Yaesu VL-1000 Quadra HF Linear

Inside Views (Click picture for larger image)

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. Click here for Quadra FAQ's.

Top view: PA Stage & LPF

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).

Bottom view: heatsink and autotuner

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 Quadra/Elecraft K3 interfacing information.

Controller board (behind front panel)

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.

VP-1000 PSU module

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.

Quadra Main Screen. Click for info download.

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).

Quadra Autotuner Screen. Click 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.

Quadra Antenna Analyzer Screen. Click for solid-state HF amplifier article.

6. User Manuals (PDF)

Copyright © 1999-2008 A. Farson VA7OJ/AB4OJ (including images). All rights reserved. Last updated 07/08/10.