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Old 17th Apr 2018, 5:43 pm   #1
John Caswell
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Default Yaesu FT101 early

A friend has brought to me an early Yaesu FT101 with the complaint of no audio on receive.
I have had a look and it looks like the Sanyo STK 401 module is defunct. I will know for sure tomorrow when I knock up an extender for it.
In the meantime has anyone here found a solution to this failed module, which of course is NLA.

John
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Old 18th Apr 2018, 12:13 pm   #2
orbanp1
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Default Re: Yaesu FT101 early

Hi John,

The service manual mentions AN214 as the audio amp IC!
The NTE1058 is also equivalent to it.
Here is a source for the AN214:
http://www.electronic-spare-parts.co.../a/an_214q.htm

The FoxTango web site also mentioned that the AN214 was a very reliable IC, for whatever it is worth.

EDIT:
Correction: Just looked at it again, the AN214 is not for the earliest audio board!
You are correct about the STK401!
Sorry for the confusion.

Regards, Peter

Last edited by orbanp1; 18th Apr 2018 at 12:22 pm.
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Old 18th Apr 2018, 12:26 pm   #3
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Default Re: Yaesu FT101 early

Harry Leeming, via Practical Wireless, is an expert on older Yaesu gear. Maybe worth contacting him.

Regards

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Old 18th Apr 2018, 1:39 pm   #4
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Default Re: Yaesu FT101 early

If that man cannot sort you, then nobody will. Email in PW or PM me.
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Old 18th Apr 2018, 5:27 pm   #5
John Caswell
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Default Re: Yaesu FT101 early

Thanks to all for the replies.
Yes I have had a look at the Fox Tango website, what a fund of useful info.
Thanks for the comment re Harry Leeming G3LLL I had forgotten all about him, to be honest I thought he had passed away! Oops!
FT gives a NTE 1511 as a suitable substitute but it is only available from the USA and I am not sure whether it is a chip or a module.
Newark appear to stock it and I can get their parts through Farnell.
I need to talk to Harry first.

John
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Old 18th Apr 2018, 6:23 pm   #6
orbanp1
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Default Re: Yaesu FT101 early

Hi John,

That NTE substitution is an interesting one, with the NTE1511 being a "5–Step LED Driver for Linear Scale".
It certainly does not look like the Sanyo chip:
http://www.nteinc.com/specs/1500to1599/pdf/nte1511.pdf
So those guys at FT must know something that I do not know!
My guess would be that this is a typo.

I could not find a datasheet for the STK401, only for some later versions that are for high power stereo amps.
Also, finally found an FT-101 manual that shows the schematics with the STK401!
The STK401 looks like an "op-amp style" power amp. Not knowing what is the value of the internal feedback resistor (that is why you would need the data sheet) one can not calculate the gain.
I would hazard to guess that the gain in that application is somewhere between 30dB to 50dB.
As a replacement I would use a TDA2003 or similar, and would set the gain to 40dB initially, and would change (fine tune) it as required.

Regards, Peter

Last edited by orbanp1; 18th Apr 2018 at 6:46 pm.
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Old 19th Apr 2018, 12:31 pm   #7
John Caswell
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Default Re: Yaesu FT101 early

Hi Peter,
Well suppose it would have helped if I had typed the correct prt nr. NTE1151 D'oh.
Senile decay setting in early here.
I will contact Harry Leeming to see if he can offer any advice or comments then go from there and report back here.

John
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Old 26th Sep 2018, 9:27 pm   #8
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Default Re: Yaesu FT101 early

Hi John, did you manage to contact Harry?

Cheers

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Old 26th Sep 2018, 10:24 pm   #9
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Default Re: Yaesu FT101 early

I rebuilt a dead early 101a few years ago and Harry was a good source of enthusiasm and knowledge. I didn't have your fault though. Good luck

David
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Old 27th Sep 2018, 9:01 am   #10
John Caswell
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Default Re: Yaesu FT101 early

Yes I did manage to contact Harry who is still going strong.
Unfortunately he no longer has any parts so I returned the unit to the friend as he didn't wish to spend any money on it.

John
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Old 27th Sep 2018, 12:07 pm   #11
G4YVM David
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Default Re: Yaesu FT101 early

Oh thats a shame. They are lovely bits of kit to use. Still, all good things etc
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