On 8/9/2010 3:22 PM, Joe Subich, W4TV wrote:
> > Just watch the plate voltage drop in a typical amp as you add
> > compression. Unprocessed SSB in a typical amp may show 100 volt drop
> > while heavily processed with compression and clipping might show a 300
> > volt drop.
>
> A 300 V drop in a 2500V supply is less than 1.5% ... that's not even
> in the same league as a 2V drop (11.5V under load) for a 13.8V power
> supply. The IMD in a 100W transceiver on a Gamma supply makes the
> Italian CB amplifiers look good.
>
And?... It's an example to show the difference between raw SSB, and
heavily processed SSB or even steady carrier. When you get to high
current low voltage the difference becomes much more and requires much
more capacitance for good voltage regulation. A SS amp may be able to
run on 12, 24, 48 or even 100 volts, but that low voltage doesn't come
for free.
73
Roger (K8RI)
> 73,
>
> ... Joe, W4TV
>
>
> On 8/9/2010 3:09 PM, Roger wrote:
>
>>
>> On 8/9/2010 11:49 AM, Joe Subich, W4TV wrote:
>>
>>> > However, by putting a very large capacitor AT THE AMPLIFIER, you
>>> can
>>> > use smaller wires and a smaller power supply. The capacitor charges
>>> > during periods of low current draw and then supplies power when
>>> > needed.
>>>
>>> This only works with CW and unprocessed SSB. Heavily processed SSB
>>> and digital modes have a sufficiently high duty cycle (low peak to
>>> average ratio) that the capacitor is not able to completely charge.
>>>
>>>
>>>
>> Just watch the plate voltage drop in a typical amp as you add
>> compression. Unprocessed SSB in a typical amp may show 100 volt drop
>> while heavily processed with compression and clipping might show a 300
>> volt drop. Coming from a different direction, look at the PEP output.
>> An amp may be capable of 1100 watts continuous carrier, key down, but it
>> might actually make the 1500 PEP legal limit with unprocessed SSB. NOTE
>> both examples are highly dependent on the individual amp so YMMV doing
>> your own experiments.<:-))
>>
>> 73
>>
>> Roger (K8RI)
>>
>>
>>
>>> This effect is seen with transceivers using the Gamma Research HPS-1A:
>>> http://www.gammaresearch.net/hps-1a.html. Better a properly sized
>>> switching supply ... for example, the MFJ-4125 is about $80 on-line
>>> for a 22A continuous/25A peak rating vs. $170 for the HPS-1A with its
>>> 5A continuous/22A peak rating.
>>>
>>> 73,
>>>
>>> ... Joe, W4TV
>>>
>>>
>>> On 8/9/2010 11:11 AM, Vic K2VCO wrote:
>>>
>>>
>>>> The capacitors don't replace batteries, but they can save a lot in
>>>> power supply and cable size. I used to have a ss amp which required
>>>> around 90A at 12v, and I used a pair of 75 amp Astrons and some huge
>>>> 00 gauge welding cables to keep the drop down (connecting them to the
>>>> amp was interesting).
>>>>
>>>> However, by putting a very large capacitor AT THE AMPLIFIER, you can
>>>> use smaller wires and a smaller power supply. The capacitor charges
>>>> during periods of low current draw and then supplies power when
>>>> needed. These are popular here with the morons that have insanely
>>>> powerful audio amplifiers in their trucks.
>>>>
>>>> On 8/9/2010 2:59 AM, Mike Tubby wrote:
>>>>
>>>>
>>>>
>>>>> I agree. With decent AGM batteries I can't really see the need
>>>>> for capacitors.
>>>>>
>>>>> I have worked with AGM SLA betteries for many years in Ambulance
>>>>> electrical systems. I also use them to power various repeaters and
>>>>> have a split charge system in my SUV for powering ham radio
>>>>> equipment.
>>>>>
>>>>> The trick to getting good performance and good outcomes is all to
>>>>> do with how you treat your batteries (charge/discharge).
>>>>>
>>>>> Most SLA AGM batteries can be used with stepped charging with the
>>>>> harder charging at 14.4V and float/maintained charging at 13.8V.
>>>>> Most SLA batteries shouldn't be discharged below 10.8V as this may
>>>>> permanently damage the chemistry - consider a low voltage
>>>>> disconnector.
>>>>>
>>>>> There's some good information over at Battery university:
>>>>>
>>>>> http://www.batteryuniversity.com/>
>>>>>
>>>>> Regards
>>>>>
>>>>> Mike G8TIC
>>>>>
>>>>>
>>>>>
>>>>>>> Has anyone ever built a power supply system with a capacitor??
>>>>>>> what suggestions for doing it right? any url for a source on
>>>>>>> such an installation? Anything else need to be added like a low
>>>>>>> voltage cutoff, isolator, etc?
>>>>>>>
>>>>>>> thanks in advance
>>>>>>>
>>>>>>> chas k5dam
>>>>>>>
>>>>>>>
>>>>
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>>>
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