General SMD Soldering Question

[Wyn Hughes]

This is distantly related to the mainstream of Q&A on this net.I intend to use my new K2 to drive a Icom IC-2KL amplifier. Please imagine for now, there is an intermediate amp between the K2 and the 2KL.

One of the twin PA boards on the 2KL ( a backup, I have 2 of them) is unfortunately, smoked. My immediate task is to solder a pair of 1KV Syfer  ceramic SMD 0.1 mfd caps between two troubled pcb tabs in the PA output coupliing stage, where the previous incumbents were vaporized, by previous owner. I think he/she ran it into a low R/high C load on 80 or 160.

This is a heavy solder job at least as heavy as the KPA100 (judging from the manual). I think I may need to solder extension tabs to the caps, which are about 5mm wide, to bridge a 10-15mm gap between the tabs on the PA board. Of course, I need to clean up all the carbon residu on the PA board and tidy up the tabs first.

How does one go about this task? Is a solder iron loke a Hakko 936 the best tool or should I use a hot air SMD soldering unit or even an oven? Should I use solder paste or ordinary 63/37 Kester 44? What temps shuld one use? I normally run the Kester 44 at 750F, as per the recommendation on their website.

Comments  much welcomed.

Wyn, VR2AX

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[Don Wilhelm-3]

Wyn,

If you have the hot air gun or oven and solder paste and know how to use it,
by all means go that route, but if not, then just use the Hakko - you will
be soldering two widely spaced tabs on the capacitors rather than finely
spaced leads like are encountered on SMD ICs.  Yes, the Kester 44 will work
just fine if the diameter is small enough to properly control the amount of
solder applied.

If the copper area is large, crank the heat on the Hakko a bit higher or use
a larger iron.

Since you have a 15 to 20 mm gap on the PC board, why not use capacitors
with leads rather than the SMD variety (unless you already have the SMD caps
in hand).  The extension tabs that you add will likely have just as much
inductance as the capacitor leads.  Of course, if this amp is for use at
VHF/UHF, then  any extra inductance may matter, but likely not for HF.

73,
Don W3FPR

> -----Original Message-----
>
> This is distantly related to the mainstream of Q&A on this net.I
> intend to use my new K2 to drive a Icom IC-2KL amplifier. Please
> imagine for now, there is an intermediate amp between the K2 and the 2KL.
>
> One of the twin PA boards on the 2KL ( a backup, I have 2 of
> them) is unfortunately, smoked. My immediate task is to solder a
> pair of 1KV Syfer  ceramic SMD 0.1 mfd caps between two troubled
> pcb tabs in the PA output coupliing stage, where the previous
> incumbents were vaporized, by previous owner. I think he/she ran
> it into a low R/high C load on 80 or 160.
>
> This is a heavy solder job at least as heavy as the KPA100
> (judging from the manual). I think I may need to solder extension
> tabs to the caps, which are about 5mm wide, to bridge a 10-15mm
> gap between the tabs on the PA board. Of course, I need to clean
> up all the carbon residu on the PA board and tidy up the tabs first.
>
> How does one go about this task? Is a solder iron loke a Hakko
> 936 the best tool or should I use a hot air SMD soldering unit or
> even an oven? Should I use solder paste or ordinary 63/37 Kester
> 44? What temps shuld one use? I normally run the Kester 44 at
> 750F, as per the recommendation on their website.
>
> Comments  much welcomed.
>
> Wyn, VR2AX
>
>

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[Wyn Hughes]

Thanks, Don:

I have a larger iron and will try that approach first. I could also have
tried to source other caps but instinctively went first for something
similar to what was there before.

Again, greatly appraciate your advice,

73
Wyn, VR2AX
----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Wyn Hughes" <[hidden email]>; <[hidden email]>
Sent: Thursday, July 27, 2006 11:29 PM
Subject: RE: [Elecraft] General SMD Soldering Question

> Wyn,
>
> If you have the hot air gun or oven and solder paste and know how to use
> it,
> by all means go that route, but if not, then just use the Hakko - you will
> be soldering two widely spaced tabs on the capacitors rather than finely
> spaced leads like are encountered on SMD ICs.  Yes, the Kester 44 will
> work
> just fine if the diameter is small enough to properly control the amount
> of
> solder applied.
>
> If the copper area is large, crank the heat on the Hakko a bit higher or
> use
> a larger iron.
>
> Since you have a 15 to 20 mm gap on the PC board, why not use capacitors
> with leads rather than the SMD variety (unless you already have the SMD
> caps
> in hand).  The extension tabs that you add will likely have just as much
> inductance as the capacitor leads.  Of course, if this amp is for use at
> VHF/UHF, then  any extra inductance may matter, but likely not for HF.
>
> 73,
> Don W3FPR
>
>
>> -----Original Message-----
>>
>> This is distantly related to the mainstream of Q&A on this net.I
>> intend to use my new K2 to drive a Icom IC-2KL amplifier. Please
>> imagine for now, there is an intermediate amp between the K2 and the 2KL.
>>
>> One of the twin PA boards on the 2KL ( a backup, I have 2 of
>> them) is unfortunately, smoked. My immediate task is to solder a
>> pair of 1KV Syfer  ceramic SMD 0.1 mfd caps between two troubled
>> pcb tabs in the PA output coupliing stage, where the previous
>> incumbents were vaporized, by previous owner. I think he/she ran
>> it into a low R/high C load on 80 or 160.
>>
>> This is a heavy solder job at least as heavy as the KPA100
>> (judging from the manual). I think I may need to solder extension
>> tabs to the caps, which are about 5mm wide, to bridge a 10-15mm
>> gap between the tabs on the PA board. Of course, I need to clean
>> up all the carbon residu on the PA board and tidy up the tabs first.
>>
>> How does one go about this task? Is a solder iron loke a Hakko
>> 936 the best tool or should I use a hot air SMD soldering unit or
>> even an oven? Should I use solder paste or ordinary 63/37 Kester
>> 44? What temps shuld one use? I normally run the Kester 44 at
>> 750F, as per the recommendation on their website.
>>
>> Comments  much welcomed.
>>
>> Wyn, VR2AX
>>
>>
>

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