[AMRadio] Power Supply Question

[Kim Elmore]

Thanks very much to everyone who responded. This is pretty much what I 
thought, but wasn't sure given the dynamic requirements of an AM PS. The 
Globe Champ seems to not have a very "stiff" supply, as I see the plate 
current decrease a bit under modulation instead of remain constant.  I 
understand that this is a common characteristic of the old transmitters and 
that it's not anything to get wrapped around the axle about.

I'm trying to interest Dad in participating in the Heavy Metal Rally on the 
27th. Even though the Globe Champ is heavy, it's not 250 lbs worth, and it 
won't make 250 W output (275 input is the AM limit).  But I bet he'd have 
fun!  We'll see.  At 81 y old, he can be a bit cantankerous at times, 
though he's earned every minute of cantankerosity...

73,

Kim Elmore, N5OP

At 05:31 PM 12/9/2003 -0600, you wrote:
>I wish to avail myself of the knowledge here: My Dad, W5JHJ, has a WRL 
>Globe Champion 350 and is the original owner.  He's maintained it and it 
>works well, but I wonder if a mod he made years ago was a good one.  Like 
>most AM transmitters, it uses a choke-input PS design.  I cannot recall 
>the input choke values, but do recall that it incorporates a swinging 
>choke and that the filter capacitor was originally quite small (2 uF, I 
>think). that capacitor failed some time ago, and as I was looking at his 
>documentation saw that he'd replaced it with something like 40 uF.
>
>On the list, I recall scrolling across a few postings (now lost) that said 
>something about how these PS should be designed. There, I thought I saw 
>something along the lines of it being possible to have too much filter 
>capacitance.  Did I get that right?  If so, what's the symptom of too much 
>filter capacitance in a choke input filter?
>
>Kim Elmore, N5OP
>                           Kim Elmore, Ph.D.
>                        University of Oklahoma
>         Cooperative Institute for Mesoscale Meteorological Studies
>"All of weather is divided into three parts: Yes, No, and Maybe. The
>greatest of these is Maybe" The original Latin appears to be garbled.
>
>_______________________________________________
>AMRadio mailing list
>AMRadio at mailman.qth.net
>http://mailman.qth.net/mailman/listinfo/amradio

                           Kim Elmore, Ph.D.
                        University of Oklahoma
         Cooperative Institute for Mesoscale Meteorological Studies
"All of weather is divided into three parts: Yes, No, and Maybe. The
greatest of these is Maybe" The original Latin appears to be garbled.