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ft101 Problem

 

I have an FT-101 that I used back in the 70s.? I was trying it out today with a long wire antenna.? I fired it up, tuned it in, everything went fine.? Then I moved it from one surface to another while it was on.? Bad Idea I guess.? It went dead as I was moving it.? There was a slight smell of burned electronics just for a second.? The smell didn't persist.

I checked and the power input fuse was blown.??I pulled off the case and examined it as carefully as I could.? Looked all through the power supply.? No sign of any arc or burned component.? Same everywhere else I could see.? At this point no smell of burned electronics.

I got another fuse and decided to give it a try without the mic to make sure it didn't slip into transmit mode.

Lights and fan came on, but no reception.? Silence.? Nothing on the s-meter.

Anyone have any thoughts?

--Kenoli
 

Did you also check the antenna overload fuse?
 

No.? Is that the lamp next to the antenna connection? Does the lamp function as a fuse?? The lamp is not blown.

Or...can you tell me where it is?

Thanks,

--Kenoli
 

Yes. The older 101 radios used a lamp as a fuse from the antenna jack to the receiver stages.?
You still could just have a blown dual gate FET on the smaller board near the VFO.?
That FET is mounted in a socket for a simple replacement as they can fail easily.?
If it is bad, use a dual gate FET that has the built in diode protection.?


On Mon, Nov 29, 2021 at 12:55 PM Kenoli Oleari KB6EMG <kenoli@...> wrote:
No.? Is that the lamp next to the antenna connection? Does the lamp function as a fuse?? The lamp is not blown.

Or...can you tell me where it is?

Thanks,

--Kenoli

 

Thanks so much for the suggestion.? Is there an easy way to test? the FET?? I will check it if I can, or just order a new one and see what happens.? Anything else I could easily check.? I thought if the tube heaters didn't go on it would indicate a power supply failure and if they did it would indicate a problem elsewhere.? I did smell something briefly and then nothing.? I looke everywhere I could carefully and saw no indicators of a burn.

--Kenoli
 

If you smelled something, I would pull out the regulator board that is along side the RF power tube cage and inspect it for damage.?
The other one to look at would be the board underneath that has high voltage parts, diodes and bias supply parts.?

On Tue, Nov 30, 2021 at 8:06 AM Kenoli Oleari KB6EMG <kenoli@...> wrote:
Thanks so much for the suggestion.? Is there an easy way to test? the FET?? I will check it if I can, or just order a new one and see what happens.? Anything else I could easily check.? I thought if the tube heaters didn't go on it would indicate a power supply failure and if they did it would indicate a problem elsewhere.? I did smell something briefly and then nothing.? I looke everywhere I could carefully and saw no indicators of a burn.

--Kenoli

 

Can you give me a better location description.? I have found the VFO circuit board (1056) inside the box that holds the main VFO adjustment capacitor but see no removable FETs anywhere in the area.? There are two soldered? active devices on the board but they look like transistors.
 

Here are some photos.

Library - 1 of 2.jpeg
Library - 2 of 2.jpeg

 

Yeah ... that is all the wrong part to be looking at.?
I’ll take the lid off one of mine and take
A photo of it

On Tue, Nov 30, 2021 at 4:05 PM Kenoli Oleari KB6EMG <kenoli@igcwrote:
Here are some photos.

 

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Great. ?Thanks.

—碍别苍辞濒颈

On Nov 30, 2021, at 3:36 PM, Bruce Collins <kb0tj1@...> wrote:

Yeah ... that is all the wrong part to be looking at.?
I’ll take the lid off one of mine and take
A photo of it

On Tue, Nov 30, 2021 at 4:05 PM Kenoli Oleari KB6EMG <kenoli@igcwrote:
Here are some photos.



 

Before I go too far, look at this site for board recognition.
You are looking for the RF unit, "front end"?board that is to the right of the VFO as viewed from the top of the radio with the lid off.?



On Tue, Nov 30, 2021 at 6:58 PM Kenoli Oleari KB6EMG <kenoli@...> wrote:
Great.? Thanks.

—碍别苍辞濒颈

On Nov 30, 2021, at 3:36 PM, Bruce Collins <kb0tj1@...> wrote:

Yeah ... that is all the wrong part to be looking at.?
I’ll take the lid off one of mine and take
A photo of it

On Tue, Nov 30, 2021 at 4:05 PM Kenoli Oleari KB6EMG <kenoli@igcwrote:
Here are some photos.



 

Thanks for the reference.? I found the board and the replaceable FET.? Could the bad FET cause completely silent reception and no transmit?? When reading up on the symptoms what I read is more like garbled reception.? I get lights and fan and nothing else.? Silence.

--Kenoli

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