[Amps] SB-220 6M conversion

Jim Thomson jim.thom at telus.net
Sat Jun 6 12:41:23 EDT 2020

Date: Sat, 6 Jun 2020 09:28:30 -0400
From: Artek Manuals <Manuals at ArtekManuals.com>
To: n2ic at arrl.net, "Amps at Contesting.com" <amps at contesting.com>
Subject: Re: [Amps] SB-220 6M conversion

<Running in the CW position just to be on the safe side ( after all this 
<amp is nearly 40 years old) Going easy on the power transformer. I can 
<only get about 100 more watts in SSB position


##  what EXACTLY  are you using to  measure  power output ???
I have a buddy  with a hb  8877  6m amp.  Eff  was low,  we tried
every trick in the book...with  small incremental  increases. 
Turns out the   NEW bird slug was way off...on the low  side ! 
Use a bird or  coaxial dynamics slug, the  25-60 mhz type, for a 
bird  43  line section.

## Toss those  useless   grid caps...and  ditto  with grid chokes.
Chassis ground all  6  x grid  pins  with .375 inch wide strap.
That alone will result in  20-25  watts  less drive required....or
conversely, more power output for  same amount of  drive you had before.

##  Use a flat strap wound tank coil,  with  at least  .375 inch  wide  copper strap,
and preferably .5 inch wide  copper strap.

##  Use a PI net for the  tuned input, with the typ  C1 – L –C2  setup.
Use  10-12  gauge wire for the  coil on the  tuned input.  When  driven
full bore,  you should have 1 to 1  input  swr. 

##  what did you use for the plate choke ??  10 uh is ample.  You want the
1st  series resonance  above  55 mhz.  22 gauge magnet wire  wound on
teflon or ceramic  will work.

##  Dunno about oem parasitic suppressors. I cant see the oem heath suppressors
working at all on  6m.

## what xcvr are you using for  6M ?  What is the max power out of the  xcvr ?
How much  grid and plate current..and loaded  B+  do you have on the  SB-220 ? 

Jim  VE7RF

More information about the Amps mailing list