[Amps] SB-220

[R.Measures]

On Dec 27, 2004, at 7:16 AM, Dan wrote:

> Richard,
> I would think the inrush protection as on your site would no doubt be 
> good regardless just to calm everything down a little when the amp is 
> switched on.. Even though the 811H HV is at 1700 volts  I have looked 
> at the circuit on your site and assume it would have to be changed a 
> little on the Ameritron as the Ameritron 811H does not have a relay  
> from transformer as noted.

A separate relay is required for step-start, no matter how the 
amplifier is switched on.  The relay coil-V can be 12vdc, or whatever 
DC-V is available from the extant relay PS.  - note - For a 12vdc coil, 
FWD rectify the fil's 6V-ac and use a series-R with the coil to set 
make at 2/3 of normal HV.  Also, a FWD might provide enough rectified V 
to pull in a 12v relay.

> Unless i am missing someting. Either way seems like the way to go. I 
> looked at Ameritron's external inrush device, but the problem I see 
> with an external unit is the fact that you must switch the amp on and 
> off from the external unit not the amp making it a little un-handy if 
> say the evice is under a desk that the amp sits on etc..
> What about leaving it on..... his first question.

Not including a step-start in an amplifier increases sales of their 
external step-start unit.  Mo' profits, supersize fries, and mo' bigga 
SUVs are always mo' better in America.  I have think there would be a 
market for an amplifier that has no design flubs.  Afterall, this stuff 
isn't rocket science.

> I too come inhere early morning and tend to switch on the radio to 
> isten in ona couple of nets etc. i might not actually go on air much 
> during that time.But in result is it is on much of day Is there a 
> recomended time etc to follow as far as switching on the amp I like 
> having it ready to go .. but not sure how much life i take out of it 
> if i sits 80% on on time .. tnx

I see no reason to let thoriated tungsten filament tubes idle, but 
heater-type tubes, yes.  Any HV-PS benefits from a step-start.

> Dan
> PS- if youhave a circuit design for a step start  that would wokr in 
> the 811H let me know
> *********** REPLY SEPARATOR ***********
> On 12/27/2004 at 7:05 AM R. Measures wrote:
>> Dan -- I have never measured the fil V in an AL-811. The only RF-Tx
>> amplifiers that do not benefit from a step-start are those that 
>> already
>> have one. The Henry 3K-A is one example.
>>
>> On Dec 27, 2004, at 6:53 AM, Dan wrote:
>>
>>> Richard & others...
>>>
>>> How does the Ameritron 811H fit into this same questions thanks
>>> Dan
>>> ==
>>>
>>>
>>> *********** REPLY SEPARATOR ***********
>>> On 12/27/2004 at 6:48 AM R.Measures wrote:
>>>> On Dec 27, 2004, at 2:33 AM, Larry Stowell wrote:
>>>>
>>>>> I have a SB-220 and am wondering if it is better to turn it off 
>>>>> when
>>>>> its not going to be used for a couple of hours? I turn my radio's 
>>>>> on
>>>>> early morning and leave them on most of the day.
>>>>
>>>> The good thing about leaving a SB-220 on is that it has a reasonable
>>>> of
>>>> filament-V, so not much emissive life will be wasted by wasting the
>>>> electricity. The bad thing about starting a SB-220 is that the 
>>>> inrush
>>>> current caused by the C-filter exceeds the peak-I rating of the 
>>>> ON-OFF
>>>> switch, which will eventually cause the switch to fail. For longest
>>>> life, install a step-start such as the one at Figure 1 on my Web 
>>>> site
>>>> and oil the fan bearings every two years.
>>>> - cheers, Larry
>>>>>
>>>>> Larry K1ZW
>>>>> Durham, NC
>>>>
>>>> Richard L. Measures, AG6K, 805.386.3734. www.somis.org
>>>>
>>>
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>>>
>>
>> Richard L. Measures, AG6K, 805.386.3734. www.somis.org
>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org