[ARC5] Converters for Q5-ers (PS hum)

[Dennis Monticelli]

On my BC-453 I either run batteries as you do, Bill, or I use HP bench
supplies, which have excellent output noise specs.  The local noise
environment is bad enough as it enters from the antenna without having to
worry about direct feed of line noise into the receiver circuitry.

Dennis AE6C

On Tue, Jan 20, 2015 at 7:38 AM, Bill Cromwell <wrcromwell at gmail.com> wrote:

> Hi,
>
> I have found that running my BC-453 on pure, battery supplied DC makes a
> tremendous difference. The difference between playing radio or playing the
> accordion (different hobby) instead. The apparent source of background
> noise is man made crap and crud coming in on the power line and not so much
> the 50/100 or 60/120 cycle hum. I fretted and studied and poked at the
> incoming noise and suspected my antennas for a long time and frankly
> considered just giving up radio entirely! My final, desperate act was
> setting up batteries to operate the BC-453. Epiphany time! In my case the
> DC heater line *does* make a big difference but it might be defeated if the
> DC is derived from the AC line without good filtering on the AC line at the
> input. Next I am going to visit the AC input filters that are supposed to
> be installed on *ALL* switching power supplies but are often omitted. I
> tamed a PC by installing the parts that had been jumpered/omitted.
>
> I use a pair of 12 volt lead-acid batteries in series for the heater
> strings, and I started with ten 9-volt batteries in series for ~90 volts
> B+. Then I tried it with five 9-volt batteries and I got the same result
> with about half the current! So 45 volts it is. If there was any difference
> in volume in my cans I could not notice it. Running speakers from across
> the gymnasium might be different.
>
> The other difference the DC on the heaters might make is when the DC is
> regulated so the heater current is stable. The two L-C oscillators will
> drift noticeably as the AC line voltage varies with load changes - such as
> when the blower on my furnace comes on. When the blower turns off again the
> oscillators drift back the other way. I don't miss that, either.
>
> If I had spent the amount of time practicing with my accordion that I
> *wasted* trying to clean up the signals with antenna changes I would enjoy
> both hobbies a lot more <wink>.
>
> Just my personal results.
>
> 73,
>
> Bill  KU8H
>
> On 01/20/2015 12:06 AM, Kenneth G. Gordon wrote:
>
>> On 20 Jan 2015 at 12:59, Leslie Smith wrote:
>>
>>
>>
>>  DC filament supply v AC filament supply. Does AC to the filaments
>>> matter?
>>>
>> No. Not one whit. Absolutely not.
>>   Ken W7EKB
>>
>
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