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Reviews For: Yaesu FL-1000

Category: Amplifiers: RF Power - HF & HF+6M

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Review Summary For : Yaesu FL-1000
Reviews: 1MSRP: $400 (Circ 1965)
Description:
Yaesu FL-1000 HF Linear (Circ 1965) 1200w PEP Input.
The Yaesu FL-1000, the companion amplifier for the Yaesu "F" line. The FL-1000 uses four 6JS6C final amplifier tubes in ground grid configuration.
Product is not in production
More Info: http://www.foxtango.org/FL%20Amplifier%20Evolution.htm
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0014
DL9BDM Rating: 2021-04-05
Now a rare collector's item from the early days of Yaesu Time Owned: 3 to 6 months.
No one has written a review here yet, so let me start. Some time ago I was able to get a Yaesu FL-1000 that was still in virgin, i.e. unmodified and clean condition. However, the original 6JS6A were unfortunately completely used up, a conversion to 4 x EL519 (6KG6) was an option, which only required the replacement of the original Compactron B12C/12BJ tube sockets. Good Magnoval B9D ceramic tube sockets are relatively easy to get on Ebay, as the EL519 tubes too. When swap the tube sockets nothing has to be changed on the chassis, the mounting holes also fits the new sockets. I decided not to reinstall the ALC circuit because I not needed and it was previously at the unused socket connections of the 6JS6A, which is not possible with the new EL519, because there are no free connections left at the new sockets.

In its original state, this amplifier does not have a broadband choke at the output of the PI filter. However, this is absolutely necessary for safety reasons. If the anode side capacitor breaks down, it short-circuits the anode voltage to ground and prevents this voltage from being applied to the antenna.

I also installed a 10 ohms 10 watts glitch resistor and a 1.5 ampere anode fuse. In addition, the measuring instrument is now protected against overload and possible flash overs with two anti-parallel high-current diodes. I highly recommended this additions, not only in this amplifier.

Unfortunately, the original mains transformer only brings a low anode voltage of less than 700 volts AC (around 200 plus volts more would be better). I didn't want to change that. So the power amplifier now "only" has about 400 plus/minus watts RF output again, which also corresponds to the original specifications.

Of course I have to reset the anode idle current to about 90 mA after the conversion.

I only use transceivers with RF power tubes and output PI filters, the untuned input circuit in the FL-1000 is not a problem here. With modern transistor transmitters this is certainly more problematic and an interconnected matchbox then ensures good matching with low input SWR, without modifing the input circuit of the amplifier. Another good idea is a 50 ohm broadband input circuit with impedance transformation, as suggested by PA0FRI.

Above all, it was important to me that the originality of the FL-1000 would be preserved and that it can be restored to the original condition without a trace, because this is now a classic item for the collecting HAM.