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Drake SW4A AGC issues part three
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Hi everyone,
I wanted to update the progress on my SW4A problems with the AGC causing distortion with strong signals. Over the Christmas holiday, I installed the tri-section electrolytic capacitor I got for Hayseed Hamfest. I don¡¯t know if I scared the bejesus out of the radio with my 100W soldering iron, or perhaps a wire got moved? For whatever the reason, the old Drake SW4A is working fine. No distortion at all. Chalk that one up to the unexplained. Mike, WB8VGE The Heathkit shop |
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Whoa, wait a minnit, you changed the capacitor and the distortion went away? And its a mystery? Am I misreading this?
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On 1/6/2024 8:03 AM, mike bryce wrote:
Hi everyone, --
Richard Knoppow Los Angeles WB6KBL SKCC 19998 |
¿ªÔÆÌåÓýYup, that¡¯s what happened. And of course when I tack soldered in some caps to check operation, I had the distortion. So, when the new cap went in, it¡¯s gone. I¡¯m thinking it might have been a wire issue (too close to something)?for whatever reason, the SW4A is working as it should now Mike, WB8VGE
A man with one clock knows what time it?is. A man with two clocks is never sure. |
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I may have simplified this¡
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when I was working on the receiver, I tack soldered some electrolytic capacitors in the power supply, still had the distortion. New cap came in, removed the ones I used to check operation and the distortion is now gone. That¡¯s the mystery. Why would I have the distortion with caps I tack soldered into the circuit yet when I replaced the can (with the old caps) the distortion went away. Mike wb8vge On Jan 6, 2024, at 2:07 PM, Richard Knoppow <1oldlens1@...> wrote: |
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Just a guess, Mike, but you may have put a good cap in parallel with a leaky cap and ended up with a good leaky cap! Bob K9JU
On Saturday, January 6, 2024 at 04:39:39 PM EST, mike bryce <prosolar@...> wrote:
I may have simplified this¡ when I was working on the receiver, I tack soldered some electrolytic capacitors in the power supply, still had the distortion. New cap came in, removed the ones I used to check operation and the distortion is now gone. That¡¯s the mystery. Why would I have the distortion with caps I tack soldered into the circuit yet when I replaced the can (with the old caps) the distortion went away. Mike wb8vge > On Jan 6, 2024, at 2:07 PM, Richard Knoppow <1oldlens1@...> wrote: > >? Whoa, wait a minnit,? you changed the capacitor and the distortion went away? And its a mystery? Am I misreading this? > |
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By tacking in the capacitors do you mean you just paralleled them with the old ones? If you did not disconnect the old caps their leakage (parallel) resistance would still be there. When substituting caps the cap must be disconnected from the circuit. If you DID disconnect them what happened is beyond me. Maybe a cold solder joint that got fixed when the new one went in.
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On 1/6/2024 1:34 PM, Mike Bryce wrote:
Yup, that¡¯s what happened. And of course when I tack soldered in some caps to check operation, I had the distortion. So, when the new cap went in, it¡¯s gone. I¡¯m thinking it might have been a wire issue (too close to something) --
Richard Knoppow Los Angeles WB6KBL SKCC 19998 |
¿ªÔÆÌåÓýRichard and the gangI remove (electrically) the old cap out of the circuit before tack soldering in a test capacitor.? The test capacitors were quite a bit out of spec (I used a 47mf instead of the 8mf drake used) and that could be the issue with having the wrong capacitance in the supply.? Mike, WB8VGE
A man with one clock knows what time it?is. A man with two clocks is never sure.
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