[Heathkit] SB-200 @ 50 Hz

[Bill Cromwell]

Hi,

Another solution might be to reduce the power just a little bit. That is 
what is recommended for our ICAS designed radios anyway. Power 
reductions are required for full duty cycle use like RTTY and other 
digital modes and AM or FM phone. Further reduction in consideration of 
the power supply iron might be in order. That is not reduction from 1000 
watts input to 185 watts! If that amp is rated 1000 watts input then 
something like 800 watts plus a little on input. That is a lot more RF 
power than an amp with a fried power transformer can deliver!

I run all of my gear on the conservative side of the equation. Double 
barrel 6146 finals can deliver ~100 watts to the antenna terminals. For 
those who adore many decimal points - ICAS ratings allow an output of 
127.0831256317 watts at 50 ohms +/- 0.00125 ohms <evil grin>. I run mine 
around about 50 to 60 watts (or less) in ICAS modes (CW/SSB). They are 
getting incredibly *old*. I can't find an excuse to retire them. Of 
course they are only 50 years old or thereabout.

Best of luck to the OP with the amp.

73,

Bill  KU8H

Michigan QRP Club M1778


On 02/29/2016 03:09 AM, Donald Spoon wrote:
> From the dim recesses of my mind I seem to recall my EE Professor (in 
> 1963) saying a 50 Hz transformer has higher "core losses" than a 60 Hz 
> transformer. This results in the 50Hz transformer having more iron to 
> handle the increased heat generated from these losses.  The higher the 
> frequency the lower the losses and the smaller the transformer.  Some 
> of those 400Hz aircraft transformers are tiny compared to the same one 
> in a 50HZ or 60Hz version.  Practically speaking the difference 
> between a 50Hz and a 60Hz transformer is miniscule for the sizes we 
> Hams deal with.
>
> Now I have never owned a SB-200, but I bet that it will work OK on 
> 50HZ as long as the Transformer temp was under control.  SSB and CW 
> should work OK, but RTTY and some of the continuous Digital modes, 
> like Domino, should be watched carefully.
>
> This is the only caveat that I can think of right now if you want to 
> try.  Perhaps some of the transformer companies, like Hammond, could 
> provide you a better answer?
>
> Cheers,
> -Don- K0APK
>
>
>
> On 2/29/2016 1:16 AM, manualman at juno.com wrote:
>> Interesting, on page 4 of the SB-201 manual under Introduction, it says
>> 50/60 Hz, yet on page 44, under Power Source, it just says 60 Hz.
>>
>> Personally, I don't see where 50 or 60 hertz would make that big of a
>> difference relative to the power transformer. The fan motors in both
>> amplifiers also use the same part number AC fan.
>>
>> Pete, wa2cwa
>>
>> On Sun, 28 Feb 2016 23:32:11 -0600 Ken <ken at wa0sbu.com> writes:
>>>          Interesting, on page 4 of the SB-201 manual, it specifies
>>> "120
>>> VAC or 240 VAC 50/60 Hz lines."  They both use the same 54-151 Power
>>>
>>> Transformer.
>>>
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