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Enameled Wire Coils in Johnson Valiant

 

I recently purchased a Valiant transmitter that I'm refurbishing.? As you all know, the transmitter is full of 1/2" diameter coils made of enameled wire.? I've been told by a reputable source that the coils were originally there to prevent TVI.? I asked them if they should be replaced by molded RF chokes, and if so, what value should be used.? They told me that the coils could be eliminated when I was in there making updates to the transmitter.

I'd like to ask the folks here if any of you have removed those coils, and if so, ever found any problems.? I would love to remove them, because there are several places like the ACC socket on the rear apron, where they are really in the way inside the chassis.

Thanks!
Mike, WB0LDJ
mharmon at att dot net
James Byrnes
 

I would not remove them or change them out. They will lower the value of the transmitter and also may cause other in circuit issues that the manufacturer was aware of while design phase of this airloom..

James Byrnes
KA2DRQ


On Sun, Feb 18, 2024 at 10:22 PM, Mike Harmon
<mharmon@...> wrote:
I recently purchased a Valiant transmitter that I'm refurbishing.? As you all know, the transmitter is full of 1/2" diameter coils made of enameled wire.? I've been told by a reputable source that the coils were originally there to prevent TVI.? I asked them if they should be replaced by molded RF chokes, and if so, what value should be used.? They told me that the coils could be eliminated when I was in there making updates to the transmitter.

I'd like to ask the folks here if any of you have removed those coils, and if so, ever found any problems.? I would love to remove them, because there are several places like the ACC socket on the rear apron, where they are really in the way inside the chassis.

Thanks!
Mike, WB0LDJ
mharmon at att dot net

--
James Byrnes
 

Back in the early 1970s, we had TVI problems when operating on 15 meters.? The third harmonic fell on TV channel 3 and most transmitters of the day radiated considerable energy on channel 3.? The Drake T4 transmitter was a terrible offender.? At that time, I acquired a Valiant, which had considerable attention paid to suppressing harmonic radiation.? The cabinet sealed well to the chassis and front panel and the coils you mention along with the bypass capacitors prevented radiation from any wires connected to the rear panel.? I believe there were even metal cans around the rear of the meters.? When I installed and tested the Valiant, there was ZERO interference on channel 3 and it remained my transmitter of choice for a long time.? I guess there's no pressing reason to keep the coils in place today, but I'd keep them anyway.

73, Floyd - K8AC

Former owner of Navigator, Ranger 1, Ranger 2, Valiant 1, Challenger.
 

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The biggest issue was the designs that used 21 Mc
as the IF frequency. Nothing could fix that issue.

IIRC, the FCC finally stepped in and the problem went
away, eventually.

73, Dick, W1KSZ

From: [email protected] <[email protected]> on behalf of Floyd - K8AC <floydsense@...>
Sent: Monday, February 19, 2024 7:26 AM
To: [email protected] <[email protected]>
Subject: Re: [EFJohnson-Amateur-Radio] Enameled Wire Coils in Johnson Valiant
?
Back in the early 1970s, we had TVI problems when operating on 15 meters.? The third harmonic fell on TV channel 3 and most transmitters of the day radiated considerable energy on channel 3.? The Drake T4 transmitter was a terrible offender.? At that time, I acquired a Valiant, which had considerable attention paid to suppressing harmonic radiation.? The cabinet sealed well to the chassis and front panel and the coils you mention along with the bypass capacitors prevented radiation from any wires connected to the rear panel.? I believe there were even metal cans around the rear of the meters.? When I installed and tested the Valiant, there was ZERO interference on channel 3 and it remained my transmitter of choice for a long time.? I guess there's no pressing reason to keep the coils in place today, but I'd keep them anyway.

73, Floyd - K8AC

Former owner of Navigator, Ranger 1, Ranger 2, Valiant 1, Challenger.

 

I removed only the coils on the line cord to make room for a proper 3 wire line cord.
Also added a rear panel fuse holder properly wired in the hot side and also moved the internal fuse to the rear panel.
Everything works great.

DSC03041.JPG

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