Yaesu Quadra FAQ's

by Adam Farson VA7OJ/AB4OJ

Based on conversations with Bill Heinzinger, W9OL

Q1: I can't make the Quadra tuner work, on any band. My 40 meter antenna gets high SWR (3.5-4) on the band edges and I can't make the tuner even show that it's trying to tune.

A1: The VL-1000 requires at least 75W of drive for correct auto-tuning or bandswitching. In the MP, Menu item 4-3 Exciter Drive Power - must be set to MAX. Also, the reflectometer at the auto-tuner output will report a HI SWR error for load SWR > 3:1. There appears to be a slight non-linearity in the power/SWR relationship of this reflectometer, so at full power the amplifier may report a HI SWR error for load SWR > 2.75:1.

If the tuner appears to run for a few seconds and then stops with an ERROR indication, this is a sign that the exciter is not sending the amplifier a carrier for tuning. With a Yaesu FT-100MP or MkV as exciter, the tuning cycle consists of two processes:

  1. The "Band Data 1" (4-bit DIN) cable is connected between the exciter and amplifier BAND-DATA 1 jacks. The 4-bit code sent to the VL-1000 on the "Band Data 1" cable sets the bandswitching relays to the band selected on the transceiver.

  2. The "Band Data 2" cable (DB15 to RCA) must be connected between the VL-1000 BAND-DATA 2 jack and the MP's "REMOTE" jack to allow the next step to take place. In addition, Menu item 7-9 on the exciter must be set to "EL" (the default value). When you press the [F SET] or [TUNE] button, the amplifier keys the MP, which in transmits a CW carrier to the amplifier. The VL-1000's CPU counts the excitation frequency, and initiates band selection [F SET] or tuning [TUNE]. When the band-selection or tuning cycle is complete, the VL-1000 unkeys the MP. The TUNER screen of the VL-1000 displays 'COMPLETE' if tuning is successful.

When the autotuner has been tuned on a given frequency, the VL-1000 will memorise the tuner settings. When you tune the exciter to that frequency range again, pressing [F SET] will set the tuner to the closest memorised tuning point. This takes less time than a full tuning cycle. (VL-1000 user manual, page 7).

If the "Band Data 2" cable is not connected, pressing [F SET] will have no effect. Pressing [TUNE] will start the autotuner, but in the absence of a carrier the tuner will stop almost immediately with an 'ERROR' display.

Q2: The manual says that if I have that if the rear panel Remote switch is ON, the Quadra is turned on via the MP. Does that mean if I set the switch to OFF, I can turn the Quadra Off via the front panel switch?

A2: If the rear-panel "REMOTE" switch is in the ON position, the exciter's POWER switch will power the VL-1000 up and down. (User manual, page 8).

Q3: If I use the Band Data 2 cord with the DB15 and phono plug, do I get any extra features. It shows to hook the phono plug end into the MP's Remote jack but that's the wrong type plug...Do I need this cable?

A3: The instructions for connecting the "Band Data 2" cable are on page 4 of the user manual. The reason for the RCA plug is to accommodate non-MP exciters. For use with an MP, cut off the RCA plug and connect a 3mm mono mini-phone plug as follows:

This will correct the problem of the tuner not responding, as described above.

Incidentally, if the rear-panel "REMOTE" switch is in the ON position, the exciter's POWER switch will power the VL-1000 up and down. (User manual, page 8).

Q4: When I send CW, I hear the fans start up and continue till I stop. They also periodically run for a few seconds when just at idle.

A4: The fans in the RF cabinet can cycle on and off, or run continuously at low speed, depending on ambient. They will speed up when the VL-1000 is keyed. The fans in the PSU cabinet cycle on and off. (User manual, page 10).

Q5: PSU is on a shelf behind operating desk, in the clear with sufficient air flow around it. I'd like to place RF unit on desk and under a shelf which is part of my desk. It will be clear to the rear and about 1.5 inches of room above the RF unit to the shelf. Will this impede air flow into the RF unit?

A5: I would recommend at least 4 in. of clear space around the top, sides and rear panel (if possible), to ensure adequate air-flow. The feet should also be locked in the elevated position.

Q6: My Quadra is the "USA" version. Where can I find the 10/12m enabling procedure?

A6: The 10/12m enabling instructions are downloadable here.

There are two general caveats for safe operation of the Quadra:

  1. The auto-tuner must be disengaged when using an external tuner. Cascading tuners can reflect high reactance values back into the auto-tuner and/or LPF. As a result, dangerously high RF voltages can appear across capacitors in these networks, leading to component failure.

  2. Proper connection and adjustment of the ALC is absolutely mandatory when using a solid-state amplifier. The ALC line is the amplifierís first line of defence. Failure to properly configure ALC will place the costly RF power devices (and other components) at risk of destruction.

Here is a detailed general discussion of solid-state HF amplifiers.

Copyright © 2009-202 A. Farson VA7OJ/AB4OJ. All rights reserved. Last updated 10/09/22