Colin:
Please see my off list reply.
I simply didn't want to bog the list down with my detailed response.
73 from Tom Behler: KB8TYJ
----- Original Message -----
From: "colin McDonald" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, May 07, 2012 5:13 PM
Subject: Re: Interesting RFI Problem
> what bands does it occur on? or perhaps a better question, which bands is
> the noise the worst on?
> You could use a cap to ground from the posative lead of the speaker
> wire...this might attenuate some audio frequencies though.
> Shielding is a viable option as well...copper foil around the inside
> surface
> of the speaker case could help to prevent the rf from getting into the
> speaker coil.
> Also, what is happening is that the cheap realistic preamp is picking up
> rf
> and sending into the speaker at a far higher level than what would occur
> with an non-amplified speaker.
> An audio isolation transformer between the radio and speaker might also
> help
> to get rid of RF on that line.
> Try connecting the speaker to a properly regulated and filtered 13.8V
> power
> supply...in other words, it might be the wallwart that is causing allot of
> your problem.
> Back in my CB days, I tried amplified external speakers, and always had
> RFI
> problems through the speaker even with 4W on AM.
> Perhaps a ferrite choke between the preamp and the speaker itself, inside
> the case, might help to get rid of RF before it gets to the speaker coil.
> so there you go. As you know, with RFI, there is seldom one single thing
> that you can do to make it disappear.
> But, with enough experimentation, you can usually accomplish the task of
> making the noise go away, or at least, drastically attenuating it.
>
> 73
> Colin, V A6BKX
> ----- Original Message -----
> From: "John Miller" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, May 07, 2012 8:11 AM
> Subject: Re: Interesting RFI Problem
>
>
>>I see that with a lot of cheap computer/similar speakers. Sometimes moving
>> them away from the equipment helps, sometimes not, sometimes chokes help,
>> sometimes nothing helps, it's just one of those things.
>> ----- Original Message -----
>> From: "Tom Behler" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Monday, May 07, 2012 7:04 AM
>> Subject: Interesting RFI Problem
>>
>>
>>> Hi, all.
>>>
>>> Well, I have an interesting little RFI problem here in the home shack
>>> that
>>> I've been scratching my head over lately.
>>>
>>> At the estate sale I've been talking about, I picked up a Realistic
>>> 32-2040
>>> amplified speaker. The speaker either runs on 6 C-cell batteries, or
>>> the
>>> supplied 9-volt wallwart.
>>>
>>> The speaker sounds terrific, with excellent quality audio that I can
>>> adjust
>>> in terms of tone and volume from the speaker itself.
>>>
>>> However, when I transmit with my TS590, using my amplifier, I get lots
>>> of
>>> RFI through the speaker itself.
>>>
>>> I have tried RF chokes on both the Wallwart power cord, and the phono
>>> plug
>>> connection between the Ts590 and the speaker itself, but no joy.
>>>
>>> I have tried running the speaker just on batteries, but still get the
>>> RFI.
>>>
>>> Obviously, this particular speaker is more susceptible to RFI than
>>> usual,
>>> since I don't get the RFI at all when using other speakers such as my
>>> Motorola amplified speaker or just a standard external speaker.
>>>
>>> Does anyone have any suggestions as to what else I might try?
>>>
>>> I'd love to use the speaker since it sounds so good, but the RFI issue
>>> may
>>> make that impractical in the long run.
>>>
>>> 73 from Tom Behler: KB8TYJ
>>
>
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