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  1. YaesuFT847
  2. Topics

Schematics?

Max Donoghue
 

Hi Andy,

also notice when listening to the local repeaters, the discriminator reading on the meter is off to the left. I actually have to tune about 1.5 KHz above the repeater output if I wanted to center it. Not sure if something is out there either.
 

Depends on the input, ie might be zero

Get

Max Donoghue
 

...and if I measure at the output of Q4001 I get nothing.

I think Q4001 is toast.
Max Donoghue
 

Hi Andy

If I measure at J3006 on the RF board, I'm only getting 60mV

This output runs to the input of Q4001

If I reseat the cable and measure at pin 1 of Q4001 I only get 12.5mV? ??


Max


On Thu, Jul 14, 2022 at 10:57 AM Andrew Lenton <a@...> wrote:

OK on your detector probe:

?

?

50mW should give 1.6V input

?

Pin4 Q4001 up to 10 Watts so 22V

?

RF output 50 Watts 50V

?

73

?

Andrew

?

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 14 July 2022 15:15
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

I'll have the parts here tomorrow to build the probe. Won't have a chance to look at it until next week, it's my wife's 60th birthday this weekend!

Happy wife....

 

开云体育

OK on your detector probe:

?

?

50mW should give 1.6V input

?

Pin4 Q4001 up to 10 Watts so 22V

?

RF output 50 Watts 50V

?

73

?

Andrew

?

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 14 July 2022 15:15
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

I'll have the parts here tomorrow to build the probe. Won't have a chance to look at it until next week, it's my wife's 60th birthday this weekend!

Happy wife....

Max Donoghue
 

I'll have the parts here tomorrow to build the probe. Won't have a chance to look at it until next week, it's my wife's 60th birthday this weekend!

Happy wife....
 

开云体育

True I know it is tricky, anyhow there is some measuring to do first

?

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 14 July 2022 13:06
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

I saw that module. Wondering how legit is is? Could be a counterfeit.

 

开云体育

Off to lunch back in 90 mins

?

From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 14 July 2022 12:47
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

Hi Andy


3.66V


I'll build an RF probe.

Can't find a 1N34A. Any good subs?
Max Donoghue
 

I saw that module. Wondering how legit is is? Could be a counterfeit.
Max Donoghue
 

If you are referring to the 3.66V, that was on pin 2 of Q4001. I get 13.7V on pin 3. I'll need the probe to measure pin 1 input and pin 4 output.
 

From: [email protected] [mailto:[email protected]] On Behalf Of Andrew Lenton
Sent: 14 July 2022 13:02
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

?

Any germanium or Shockey diode will do just add .6 off a volt

?

OK 3.66V at 50 OHM + 3.8mW to 4mW

?

Where are you measuring?

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 14 July 2022 12:47
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

Hi Andy


3.66V


I'll build an RF probe.

Can't find a 1N34A. Any good subs?

dBm Voltage1.xlsx
dBm Voltage1.xlsx

 

开云体育

?

Any germanium or Shockey diode will do just add .6 off a volt

?

OK 3.66V at 50 OHM + 3.8mW to 4mW

?

Where are you measuring?

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 14 July 2022 12:47
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

Hi Andy


3.66V


I'll build an RF probe.

Can't find a 1N34A. Any good subs?
 

开云体育

?

Replacement 4001!

?

From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 13 July 2022 19:25
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

The voltages at Q4001 look good, as do the measurements at Q4006.

Does the 285mA reading seem reasonable considering Q4006 is not putting any power out?

I think Q4001 is good based on the signal strength into the handheld.? Possibly a break in the RF path between Q4001 and Q4006? I read where solder joints have been known to crack.

Max Donoghue
 

Hi Andy

3.66V

I'll build an RF probe.

Can't find a 1N34A. Any good subs?
 

开云体育

Hi max,

?

Check the voltage on Pin 2 of Q4001, this is the power control!

?

73

?

Andrew

?

From: [email protected] [mailto:[email protected]] On Behalf Of Andrew Lenton
Sent: 14 July 2022 11:55
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 13 July 2022 19:25
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

The voltages at Q4001 look good, as do the measurements at Q4006.

Does the 285mA reading seem reasonable considering Q4006 is not putting any power out? Yes Bias current for linear operation, it could go to 300mA for perfection!

I think Q4001 is good based on the signal strength into the handheld.? Possibly a break in the RF path between Q4001 and Q4006? I read where solder joints have been known to crack. There is not much than can go wrong between Q 4001 and Q4006, cracked cap maybe, you really need to signal trace, i.e is the signal far larger than, 50mW in 3 watts out is a power gain of? 18dB Q4001 provide many Watts into the final device, check solder around Q4001.

?

BR Andrew

?

?
 

From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 13 July 2022 19:25
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

?

The voltages at Q4001 look good, as do the measurements at Q4006.

Does the 285mA reading seem reasonable considering Q4006 is not putting any power out? Yes Bias current for linear operation, it could go to 300mA for perfection!

I think Q4001 is good based on the signal strength into the handheld.? Possibly a break in the RF path between Q4001 and Q4006? I read where solder joints have been known to crack. There is not much than can go wrong between Q 4001 and Q4006, cracked cap maybe, you really need to signal trace, i.e is the signal far larger than, 50mW in 3 watts out is a power gain of? 18dB Q4001 provide many Watts into the final device, check solder around Q4001.

?

BR Andrew

?

?
Max Donoghue
 

The voltages at Q4001 look good, as do the measurements at Q4006.

Does the 285mA reading seem reasonable considering Q4006 is not putting any power out?

I think Q4001 is good based on the signal strength into the handheld.? Possibly a break in the RF path between Q4001 and Q4006? I read where solder joints have been known to crack.
 

That is good news, so looks like a drive issue? or lack of

73

Andrew

Get

Max Donoghue
 

I know the presets you are talking about.? The previous owner said 440 was working at one time but hadn't used that band in a while. Went to work satellites and no output.

It's not a big deal for me, probably wouldn't use 440 much anyway. Was just hoping that I could find the fault.

On Wed, Jul 13, 2022, 10:28 AM Andy Bosworth <sidthepop@...> wrote:

Emitter is grounded.?

There is another possibility. On one of the boards is a line of presets that control output power. It could be that the UHF one is faulty, but I have no idea how that circuit works, at the moment. There is a slim chance it has been turned right off, given that you have no history of the radio working on 70.

?
 

Emitter is grounded.?

There is another possibility. On one of the boards is a line of presets that control output power. It could be that the UHF one is faulty, but I have no idea how that circuit works, at the moment. There is a slim chance it has been turned right off, given that you have no history of the radio working on 70.

?

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