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Yaesu FT-101E repair

H

Hotel Zulu

New Member
Dec 2, 2025
4
1
3
48
South Australia
Hello all.
I've recently been given a transceiver as recieve only for a bargain price, it receives well on all frequencies fitted, shows 60ma of Final Amplifier resting current, the contact relay is functioning when keyed but it won't transmit.

Upon removing the covers and discharging the large 500v capacitors using the tip of my tongue i have discovered a burnt resistor hiding in plain view under a burnt piece of spaghetti insulation.
I've removed the resistor and sure enough it's measuring as an open circuit.

In curious as to weather this component is commonly burnt out, and what may have caused it, perhaps something has been overdriven? or maybe something else is faulty causing it.

I'm unable to read a value on the resistor due to the burning but I'm going to fumble my way through the circuit diagram to work out what I need to buy.

I'd love to hear some feedback from anyone who has experience with these fantastic rigs, perhaps someone has seen this exact damage before ?

Please see the photos
View attachment 75143View attachment 75144View attachment 75145
73's
Andrew
 

Oh dear... scorching on thr chassis and components showing signs of heat elsewhere. Tis may take a month of Sundays to sort out.
 

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BC Coyote said:
Where did the original post with the pictures go? Just a big blank space there now...
Click to expand...
A short time after he posted, he edited the post to remove his images......
With the reason that
"No one is interested"
I had responded with
Have a little patience.
I think new users are under the impression that the forum is manned 24/7 for radio technical support and many users here also have real jobs during the day and help out when they can.
As I had said,

Patience is a virtue

73
Jeff
 
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Looks like Hotel Zulu is in Australia so he my find it too expensive to post overseas. Pity he edited the post out.
 
BC Coyote said:
Where did the original post with the pictures go? Just a big blank space there now...
Click to expand...

I just restored it. I will not put up with people deleting their posts like that, ESPECIALLY since it was the start of a topic and also especially for the reason he claimed......nobody interested. He posted and only waited a few hours and his original post was at 3am. WTF did he expect? As Jeff (Audioshockwav) said......patience is a virtue.
 
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The smaller, burnt resistor is R5, a 5.1k 5 Watt resistor. It's in series with the 12BY7 driver tube's screen grid. When R5 goes open circuit, no transmit. We use a 5k 5 Watt wirewound. No special reason to use a film resistor like the original. The longer resistor alongside it is R37. Resistance value is 18k ohms. Schematic says 5 Watts, more like 7 or 10 Watts. We use a 15k 10 Watt because we scored some at a hamfest eons ago. Just make REALLY SURE that R37 is *NOT* an open circuit. When that happens, the driver tube goes into turbo mode. Makes the wattmeter happy for a while and then the driver tube fails from the overload. Frequently a failed 12BY7 overloads R5 and takes it out.

Find a tube tester and make sure the driver tube is not smoked. Something ruined R5, and that tube is the number one suspect.

73
 
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