[AMRadio] Ranger driving SB220


W6OM w6om at cox.net
Mon Feb 11 20:51:20 EST 2008


Thanks Pat & others who wrote concerning how I use a Ranger to drive an
SB-220. Here is a list from my archives of things I tried.

1. The much touted pot to crank down the screen voltage.  Simple, easy mod.
Use a non conductive shaft, bring it out through the hole in the crystal
socket and you can still insert a crystal, pot the cap back on and crack it
all the way up when you want to.

2. Simply using less grid drive when tuning up the Ranger, bad idea, my
linearity goes to hell.

3. Built a 3db attenuation pad with a hand full of one watt resistors, a
couple of coax connectors a box and a switch.  "Got way too hot"

6. Built a 6db attention pad with a hand full of 5 watt resistors, a couple
of coax connectors a box and switch.  "Found the sweet spot" 
  
7. If you don't want to build an attenuator or mod the Ranger, surplus
attenuators are plentiful and on eBay, Surplus sales of Nebraska and I am
sure countless other places.



All the Best

Ron Weaver   W6OM

www.qsl.net/w6om


-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of Patrick Thompson
Sent: Monday, February 11, 2008 4:37 PM
To: 'Discussion of AM Radio in the Amateur Service'
Subject: [AMRadio] Ranger driving SB220

How did you go about getting the RF drive from the Ranger down to a level
usable by the SB220? I'm thinking about something similar to get to the
200-250 watt carrier level (or 800 to 1000 pep AM). I'm guessing the amp
won't need much more than 10-15 watts drive (40 to 60 watts pep AM) leaving
a little headroom.

I thought about a homemade pad but that's a lot of heat to throw away. Maybe
a 3db pad and turn the drive down a little?

I could lower the screen voltage but it would be nice to have the rig full
power when barefoot.

Can you get by with just lowering the drive and microphone gain?

Pat
wa4tuk

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of W6OM
Sent: Monday, February 11, 2008 12:10 PM
To: 'Discussion of AM Radio in the Amateur Service'
Subject: RE: [AMRadio] Using Heath SB 610 Monitor Scope to monitor
modulation on AM transmitter

John

The SB 610 monitor scope is one of the best all around performers for the
money you can still buy today.  I have two, one connected to the plate of
the 2nd IF on an NC 300 for monitoring the incoming signals and for transmit
it monitors a Ranger driving an SB 220 on AM.

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