Here's another one for you ,Mike; my handbook lists the driving impedance of
a 572b as 215 ohms, so for two of them in parallel that would be about 107
ohms . the first time I did an SB200 I tuned the inputs with an MFJ259 and a
110 ohm resistor from the fil to gnd. seemed to work just fine for me.
the 201 I'm "working" on now is , or will be, a little different because
I'm using all new parts, Rich's fast switching ant ckt. (vacuum relay and
reed relay) and quite a few other "little" things.It's an interesting
project, if I ever get it done !!!!! have a good day all.
carl / kz5ca
----- Original Message -----
From: "Mike Baker" <k7ddmjb@qwest.net>
To: "AMPS REFLECTOR" <amps@contesting.com>
Sent: Saturday, November 02, 2002 11:17 AM
Subject: [Amps] SB-221 input network should have read SB-201/SB-200 input
network....etc
> Guess I should have waited until morning to type my request. Didn't
> remember what I was working on this time! ;>)
> To help reduce the confusion of my original post here is a bit of
> clarification.
>
> The alleged input impedance of 200 ohms was what someone told me the
it
> was for the tubes, not the amp itself.
> I didn't remove the ferrite core from the coil, I removed the ferrite
> core and windings from the housing it was in. (PVC pipe with a SO-239
> connector on one end and two hook eyes on the other.)
> I used a capacitor tester to measure the values of the caps before I
> installed the new ones and checked the value of the originals.
> The reason I am looking for a new coil is that when I removed the
filter
> unit from the SB-201 the input network that was in place didn't work
> anymore. I wanted to make it a bit higher Q than the original so it would
> match up to solid state exciters better so I took a look at the coil sets
in
> the SB-200 to see what the differences were. All the coil numbers were
the
> same except the 40 meter coil. I don't know what the differences are
> between them as I do not have the coil out of a SB-200 to make a
comparison
> with.
> DOES ANYONE HAVE THE ACTUAL WIRE SIZE AND NUMBER OF TURNS USED ON THE
> SB-200 40METER INPUT COIL!!!
> I'll SEND THE FIRST GUY WHO TAKES THE COVER OFF HIS AMP AND COUNTS THE
TURNS
> AND MEASURES THE WIRE SIZE $10 FOR HIS EFFORTS! I HATE REINVENTING THE
> WHEEL! ;>)
> I can see right now the thing I need to add to the shack test gear is
an
> LRC meter!!
> If I had one now I would take each of the coils out and measure the actual
> value of the inductors and their tuning range. It would be useful info to
> know for future efforts.
>
> Sorry for the long windedness. I should have been a novelist...... ;>)
>
> Best 73
>
> Mike Baker K7DD
> k7ddmjb@qwest.net
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
|