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  1. YaesuFT847
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Re: Schematics?

 

开云体育

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

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

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

Re: Schematics?

 

开云体育

Off to lunch back in 90 mins

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

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Hi Andy


3.66V


I'll build an RF probe.

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

Max Donoghue
 

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

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.
Re: Schematics?

 

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

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

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

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Where are you measuring?

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

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Hi Andy


3.66V


I'll build an RF probe.

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

dBm Voltage1.xlsx
dBm Voltage1.xlsx

Re: Schematics?

 

开云体育

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

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

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Where are you measuring?

?

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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?
Re: Schematics?

 

开云体育

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Replacement 4001!

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

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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.

Re: Schematics?

Max Donoghue
 

Hi Andy

3.66V

I'll build an RF probe.

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

 

开云体育

Hi max,

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

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73

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Andrew

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

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

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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.

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BR Andrew

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Re: 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.

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BR Andrew

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Re: Schematics?

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.
Talk back or moni

 

Greetings,
I was wondering and it is possible the question has been asked and answered, so I am sorry then. The FT 847 moni feature for SSB is nice. Is there a way to enable this feature for AM and FM as well so one can monitor his modulation? I had a issue a while ago that I thought was the radio but ended up being the desktop microphone. I was even thinking of seeing if a external modulation meter could be used. Thank you.

73'
Mark?
KC3TNO?
Re: Schematics?

 

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

73

Andrew

Get

Re: Schematics?

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.

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Re: Schematics?

 

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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Re: Schematics?

Max Donoghue
 

Hi Andy,

In measuring Q4006 earlier, I get 0.725V on the base, 13.67 on the collector in both TX and RX.

The emitter measures a short to ground.

Max
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Re: Schematics?

 

开云体育

Here is the datasheet for the driver module.

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You are up against it without basic RF test equipment!

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Q4001 drives Q4006, so you need to know if Q4001 is working

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·?????? The Drive is up to 50mW, a hand held will pick this up, however, 50mW will give you 59+60dB, so if you are getting 3 Watts out of Q4001, you will still have 59+60! dB

·?????? Disconnect the 4003 and 4004, an ammeter can be placed in series from here, to measure and set the bias through it by VR4001.

·?????? With the link disconnected monitor the current into the rig, then TX on UHF the current should increase my 1-3 amps if so then Q4001 is good.

·?????? Measure the base of Q4006, it will be 0.7 to 0.75 Volts on UHF TX, if not you have a bias problem, If it is volts then Q4006 base emitter is O/CC or Toast ( check the emitter is going to ground!)

·?????? You need to measure the power coming in, 30-50mW is my guess, find a way of doing this, diode probe across 50hm resistor and a 0.1 Cap, should give 1.6V at 50mW

·?????? The service manual will set how to set VR4001. See below.

·?????? From pin 4 to the transistor’s base are the matching components from the 50 ohm output to whatever the transistor input impedance is

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If you have oscilloscope, you could try tracing the signal, but at 440MHz, you may not have much show up depending on the bandwidth of the scope!

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The variable resistors on the FT847 are known to fail, without Bias you will get very little out

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Keep in the loop.

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73

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Andrew

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From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 13 July 2022 01:14
To: [email protected]
Subject: Re: [YaesuFT847] Schematics?

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Is there anyway with the crude test equipment I have I can check for RF on pin 4 of the UHF module?

Does the 3.66V on pin 2 of the module sound right?

PF034A Driver Module.pdf
PF034A Driver Module.pdf

Re: Schematics?

Max Donoghue
 

Hi Andy,

285mA when I break the jumper and measure across in TX? mode.

Max
Re: Schematics?

Max Donoghue
 

Is there anyway with the crude test equipment I have I can check for RF on pin 4 of the UHF module?

Does the 3.66V on pin 2 of the module sound right?
Re: Schematics?

Max Donoghue
 

Hi Andy,

Maybe I didn't measure the current correctly. I put one lead on one of the jumpers and the other lead on the other. Tried both ways and nothing either way.

On 2m at 50W my power supply (Astron VS-35M) shows about 10 amps or so. Nothing on 440 when I transmit. No output showing on the radio PO meter or on my external meter.

Max
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