Protect Light






FL-7000 Protect Light Blinking

Problem: I need some help, I just bought an FL-7000 I have it all connected as per the book, I have tried everything, the antenna is resonant for 3.925, the tuner in the amp matches the antenna, but when I go to transmit the protect light starts blinking, I have the ALC connected, I am at a loss, what am I doing wrong??. Also when it's all connected I turn off the tuner in the MP, or do I. Craig WA2TWF

Solution 1: I have the same with that setup. the FT1000MP give's too much power you must use the ATT on the linear and take the FT on 50 Watts Ron

Solution 2: There is a mod for the problem you describe. You need Yaesu Technical Bulletin TB-9601. This mod
desensitizes the protection circuitry but still provides the needed protection. I did the mod on my FL-7000 and two others. All units performed flawlessly after mod. I have a copy of TB-9601 that I will scan and e-mail if you are interested. The tuner in the MP should be off. The tuner in the FL-7000 should be used if needed. W4RRD

Solution 3: I have been using a FL7000 linear for 10 years every day with a FT1000D and now also a FT1000MP, with no problems at all, the protection circuit it has been doing his job properly always at my fault:
1.Too much exciter power.
2.High SWR.
3.In the case of FT1000D, improper adjustment of DRIVE level, when not adjusted properly, there is a high power spike witch is detected by FL7000 protection. Now I use it alternately with, FT1000, FT1000MP and IC746, no problem with IC746 but just manual. In local Radio Club they have another FL7000 and they have the problem of
protection fault, I did have a look and after adjust properly ALC with exciter ( FT757 ) and drive it was working ok.
I did have problems with other exciters as Drake TR7 and Omni V ( not in QSK ) they have the big spike at first TX.
After 10 years of every day use ( yes I am at radio about two or six hours most days ) it has been my best amp investment, not use at full power always, most at 200w so the FT1000MP is at 20w and better linearity, when
needed I raise to 400 or 500w. I have been alternating others valves amps but I have had some usual faults with them ( no protection). Just before doing any mode at the amp ( if has not been before misaligned ) I will try to adjust the ALC as manual says and always watch the FR POWER control before transmitting  Jaime EA6NB

Commentary: I respectfully beg to differ. In a solid-state amplifier, the ALC line is a vital part of the amplifier's protective subsystem. On detecting an anomalous condition such as excess reflected power, PA over current, PA over temperature etc., the amplifier throttles back the drive via the ALC line. This is the amplifier's first line of defense, and the user omits it at his peril.

Therefore, correct connection and calibration of the ALC is absolutely mandatory when running a solid-state linear.

The ALC should be set to limit the power output to 550W maximum. This ensures optimum IP3 (< -30 dB). Solid-state amplifiers have far less headroom than tube designs, and increasing power output 1 dB in excess of
the design rating can degrade IP3 by as much as 5 dB.

I run a Quadra at 1 kW PEP with an IC-756Pro as exciter. Recently I ran a 2-tone test, and checked the IP3 on a spectrum analyzer. At 1 kW 2-tone PEP, at 14.1 MHz, IP3 was around -35 dB relative to each of 2 equal tones;
pushing it to 1.2 kW degraded the IP3 to -29 dB. I do not think the extra 1.5 dB (1/4 S-unit) is worth the aggravation to one's neighbours on the band. Adam, VA7OJ/AB4OJ


This site was last updated 08/27/07