[AMRadio] Home Brew


Brett gazdzinski Brett.gazdzinski at mci.com
Wed Sep 29 09:15:19 EDT 2004


It sounds simple, and the RF stuff is simple, but it's the control
and metering that adds complexity.

Step start, push to talk, grid current and voltage metering, plate
or cathode current and plate voltage meters, plate voltage control
(variac or power trans primary taps),filiment voltage control and metering,
protective bias plus grid leak bias, etc.

But overall, it is quite simple, one step at a time...

I like building a small deck just for the rf, and do the control
on a separate deck, with lots of meters and knobs to twist.
Big wire wound pots work great for grid leak resistors.

Add in control grids and it gets more complex, with sequence starting,
more power supplies and metering, overload circuits, etc.

Its loads of fun to figure out what will work with what
parts you have or can get.

On the subject of meters (I use a lot of them), I use  the cheap
radio shack meters, they used to make 0-15 volts, 0-500 ma,
and 0 to 1ma meters that took a very small hole in the panel.
I just make the scales indicate whatever I want, 0-15 volts
can be 0 to 150 volts, 0 to 1500 volts, 1.5 amps, 150 ma, etc.
The scales come off, they are held on with glue, and you
can make up your own numbers or transfer them from one meter
to another, as I think they only sell the 0-15 volt meter now.
I should use a computer program to make up real scales.

So you can have a load of meters, all the same, cheap cost,
small panel holes, and modern looking.
Shunts will give any current you want, voltage dividers
give whatever voltage you want.

Black painted panels with P touch labels looks nice, and don't
count on remembering what meter does what, or where its supposed to
read after 10 years or more, or the next guy who gets the equipment!
You can mark the correct voltage/current with a red felt tip marker.

A pair of 813's takes how much grid drive? Screen current?
Where did you run the plate current on the 4d32 rig?
Are the 4x150a filaments 6 volts, or 6.3?

Is this stuff fun or what?

Brett
N2DTS
 
 


 



-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of Schichler, Don
Sent: Wednesday, September 29, 2004 8:33 AM
To: 'Discussion of AM Radio'
Subject: RE: [AMRadio] Home Brew


Here you go - it sounds simple.

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net]On Behalf Of John Coleman
Sent: Tuesday, September 28, 2004 7:08 PM
To: 'Discussion of AM Radio'
Subject: RE: [AMRadio] Home Brew


	If I were going to build with tubes again and two hundred watts was
the carrier output that I wanted.  I would use a pair of 812s in push pull
class C and modulate with a pair of 811As push pull class B.  Run about 1500
volts @ 200 ma for 300 watts plate input on the 812s.  Find a Modulation
XFMR to match the output of 811A class B (about 12500 ohms as I remember) to
the 7500 ohm class C final. 

John, WA5BXO

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of StephenTetorka at cs.com
Sent: Tuesday, September 28, 2004 2:50 PM
To: amradio at mailman.qth.net
Subject: [AMRadio] Home Brew

Hello All:

I'd like to build my own AM transmitter.
Tube style; more than 200 watts.

Sure a heck of a lot to choose from...but I'd like to hear what you think.


OR...if someone knows of a home brew for sale....

Tnx,
Steve




______________________________________________________________
AMRadio mailing list
Home: http://mailman.qth.net/mailman/listinfo/amradio
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:AMRadio at mailman.qth.net
______________________________________________________________
AMRadio mailing list
Home: http://mailman.qth.net/mailman/listinfo/amradio
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:AMRadio at mailman.qth.net




More information about the AMRadio mailing list

This page last updated 21 Oct 2017.