Fw: HW-9 question and wants..

[William Mabry]

----- Original Message -----
From: William Mabry <n4qa at hotmail.com>
To: <Rpemers at aol.com>
Sent: Saturday, December 25, 1999 11:23 AM
Subject: Re: HW-9 question and wants..


>
> ----- Original Message -----
> From: <Rpemers at aol.com>
> To: <n4qa at hotmail.com>
> Sent: Friday, December 24, 1999 07:34 PM
> Subject: Re: HW-9 question and wants..
>
>
> > Bill,
> >
> > Thanks much for all the info.  I'm going to try to sit down tonight and
do
> > what you recommend.  Aside from the problem with 10, the rig works
great.
> I
> > really do appreciate it...wouldn't have known where to start!  I will
let
> you
> > know me progress and ask questions of ok with you.
> >
> > Merry Christmas and 73.
> >
> > Ron
> > KB9E
> >
> Ron and group,
> I built a pair of HW-9s with optional bandpacks in 1991... one for my Dad,
> W4MAI, and the other for myself. Was lucky to get them both because Heath
> abandoned its ham radio line right about that time.
> I made a couple of minor changes to our two rigs.
>
> (1) Got rid of the fixed transmitter frequency offset by leaving out C205,
> D141, L134 and R151in the "BFO" circuit.
> With its decent RIT capability, the HW-9 does not also need fixed
> transmitter frequency offset which, in my opinion, only serves to confuse
> the operating frequency issue.
>
> (2) Adjusted the "BFO" frequency to exactly 8831.2 kHz to help facilitate
> (3), below.
>
> (3) Changed the value of C341 and C345 in the narrow audio filter circuit
to
> 1.5 nanofarads  ( AKA 1500 pF, AKA .0015 uF ).
> This lowers the bandpass center frequency to 500 HZ ( ok, 467 Hz by
> formula )
> A center frequency of  700 Hz is a little high to suit my taste.
>
> (4) Added a rear panel mounted fuse holder which accepts a cute little 5mm
x
> 20 mm fuse.
> The value I picked is one amp slow-blow as the rig pulls close to an amp
> when running 5 watts out or so.Electrically placed the fuse between the DC
> power jack positive terminal and SW2.
>
> (5) Added a 3 amp ( 200 amp surge ) 200 PIV diode... a 1N5402 that just
> happened to be handy... from SW2 input side ( cathode )... to Chassis
ground
> ( anode ).
> This, of course, is the reverse polarity protection for the rig.
> If reverse polarity voltage is applied to the DC power jack, the newly
added
> fuse will blow, even if SW2 is off, provided the power supply can deliver
> the required short-circuit current. If not, the diode will, at least,
clamp
> the reversed voltage at one diode drop.
> A simpler way to protect would be to use a diode in series with the
positive
> lead ( cathode end to SW2 input ). This works great in fixed station
> applications but in portable applications, the added voltage drop would
> adversely affect useful battery life.
>
> 73 and Happy Holidays to all !
> Bill N4QA
>

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