[AMRadio] Re: Gates BC1-T operational again


D. Chester k4kyv at charter.net
Tue Feb 13 02:19:06 EST 2007


>> K4KYV has an original lower skirt for you that covers
>> the air intake filter. My brother has one of these and
>>Don also saved the vertical meter cover that I plan to
>>get from him someday.

>I have it, but it was full of mouse nests and the urine had caused it rust
>severely.  With all those little holes it will be a heck of a job to get it
>de-rusted, so I'm saving it for later in the year.  Plus it sticks out in a
>significant way and with the rig elevated on the dollies I would be bumping 
>my shins
>into it...

I think that lower skirt that covers the air intake is the most ridiculous 
looking thing I ever saw on a piece of equipment.  I have considered 
modifying mine so that it is flat instead of bulging out.  Besides looking 
so silly, it's in the way and makes the transmitter take more footprint 
space than necessary.  The only thing that has kept me from modifying it is 
the metal work involved.

I run my fans at half voltage to quieten them down.  At full speed they 
sound like a vacuum cleaner running.  Too loud for the shack near the 
operating position.  I have a switch for turning them off completely if I 
wish. Same goes  for the a.c. contactor relays.  They sound like a chainsaw. 
I modified the circuit and got mine to run off DC.  Now they're perfectly 
quiet.  The stock mod reactor in mine talked back badly, so I replaced it 
with a potted unit I happened to have on hand.

I converted the xtal oscillator to a buffer stage for the external vfo.  One 
of the xtal frequency adjusting capacitors was removed, and in the hole I 
placed a larger variable that resonates the slug tuned coil.  Now I can 
change frequency without having to remove the top of the oscillator unit and 
fiddle with the slug.  Simply a tuning knob on the  front panel.

I replaced the bakelite grid coil with an air core inductor (B&W Miniductor) 
of similar physical size, and optimum inductance  for 160.  With the stock 
coil, even on the original broadcast frequency I could never get more than 
105 or 110 mills of grid current to the final.  With the new coil I  can now 
get 150 mills with no plate voltage.  With full plate voltage the grid 
current drops to about 125 mills.

Paul, I'm still using the side panel for the meters.  If I ever decide to 
get rid of it and make a new meter panel that doesn't stick out from the 
cabinet, I'll let you know.  Again, a lot of metal work involved - and I 
hate doing metal work.

Mine didn't come with a built-in dummy load, or else someone removed it 
years ago.  No signs of impressions in the metal cabinet from removed 
hardware.  But I have an external dummy load that is of similar rating as 
the original Gates.  In its place I have some  dropping resistors to lower 
the rf plate voltage while keeping full modulator plate voltage.  This 
allows extended positive peaks.  The stock transmitter doesn't make much 
above 100% before flat-topping.

I used car polish on mine.  The cabinet had evidently been under a leaky 
roof at one time, and the paint was chaulky.  The wax brought it back to 
life.  It has some serious scratches down to bare metal, where it was 
scooted across a concrete floor on its side.  I may try to touch it up some 
day.

I mounted my modulation transformer on ceramic standoffs, and installed 
spark gaps across the secondary.  I have heard of  too many of these blowing 
up.  Mine came with a spare mod reactor and xfmr.  The xfmr was shorted out. 
Evidently the station obtained a replacement xfmr/reactor set, but the old 
reactor was still good.

The original MV rectifiers are replaced with plug-in solid state modules 
that drop in like a new tube.  I removed the filament xfmr  for the high 
voltage rectifiers to make room when I shuffled the  reactors around and 
relaced the stock talkative mod reactor.

Mine has also been modified to run CW.  Probably one of the few, if not the 
only, broadcast transmitter presently on 160 that runs CW.

The transmitter works great, but it has to be the ugliest broadcast 
transmitter ever made.  It looks more like a soda machine than a 
transmitter.  I prefer the old art deco style, or the 1030's black wrinkle 
look.

Mine works only on 160.  Have never attempted to make it multi-band or to 
convert it to 75 or 40.

I'll try to take some pictures of mine and post them on the web for viewing.

Don k4kyv 




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