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
[email protected]
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.
