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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
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