[Boatanchors] HQ-150 Line Bypass Caps Needed

[Carl]

Ive never used those filters for just bypassing but some VNA sweeps show 
them useless for blocking ham generated RF. It sounds as if they would be 
effective for some line noise. Ive built brute force LPF's for all the amps 
and even a few for TV's and VCR's back in the "old days".

On the TS-940's Ive been using a 1KVA Sola CVT which has really done wonders 
for cleaning up line crud.

Carl
KM1H


----- Original Message ----- 
From: "Drew P." <drewrailleur807 at yahoo.com>
To: "Carl" <km1h at jeremy.mv.com>
Cc: <boatanchors at mailman.qth.net>
Sent: Wednesday, August 25, 2010 10:22 PM
Subject: Re: [Boatanchors] HQ-150 Line Bypass Caps Needed


All of which brings to mind a circuit configuration I saw in equipment of 
about 30 years ago, but not in more contemporary equipment. A fairly large 
cap (often 1 uF) is connected acros the line, line to neutral, and a smaller 
but still substantial cap (often .1 uF) is connected from neutral to 
chassis. Using this configuration would not conform to today's standards, 
but would not "tickle" the user so long as the outlet were wired correctly 
and the line cord were polaized and had no open wires. It would filter 
reasonably effectively.

Another solution might be found in the use of the packaged filter modules, 
such as the IEC connector/filter modules sold by Mouser and others. These 
have a good sized (often .1 uF) cap across the line input. Both lines then 
pass through a common mode choke. The output which feeds the equipment has a 
Y cap (no bigger than .0047 uF) from each line to ground.

I have no data on how effective these LC filters might be as compared to a 
simple large C filter as Carl had mentioned. But, you can hack a hole where 
the line cord on your beloved boatanchor used to be, and install one of 
these modules. You then get the convenience of a detachable power cord (uses 
a standard 3 wire computer cord) and a goodly dose of non-originality.

Drew

--- On Wed, 8/25/10, Carl <km1h at jeremy.mv.com> wrote:

> From: Carl <km1h at jeremy.mv.com>
> Subject: Re: [Boatanchors] HQ-150 Line Bypass Caps Needed
> To: "Drew P." <drewrailleur807 at yahoo.com>, boatanchors at mailman.qth.net
> Date: Wednesday, August 25, 2010, 10:04 AM
> Perceptions, attitudes and
> regulations changed over the decades. Bypasses of .1 and .05
> were common in the early years as they actually worked even
> tho a bit of 60 Hz passed thru them to the chassis and could
> give you a tickle. This was accepted back then.
>
> Later the .02/.022 (basically the same cap but standards
> groups changed the game to justify their existence) was used
> which didnt bypass as well but tickled less.
>
> Then the nanny state came into power and decided our
> sensitive citizens shouldnt be exposed to such torture and
> the .01 or .0047 became standard and is generally useless
> except for very short spikes.
>
> Carl
> KM1H
>
>
>
> ----- Original Message ----- From: "Drew P." <drewrailleur807 at yahoo.com>
> To: <boatanchors at mailman.qth.net>
> Sent: Tuesday, August 24, 2010 10:45 PM
> Subject: Re: [Boatanchors] HQ-150 Line Bypass Caps Needed
>
>
> > Hello Bill,
> >
> > Voltage ratings have been established so that the line
> bypass caps will withstand most of the sometimes horrendous
> transients encountered on the line. They are designed
> to "fail safe" on very large transients - Y caps will fail
> open so as not to make the chassis "hot". X caps will not
> catch fire so as not to make the chassis "hot" in another
> way.
> >
> > You might peruse the information available here:
> >
> > http://my.execpc.com/~endlr/line-filter.html
> >
> > Drew
> >
> >
> > Bill Stewart wrote:
> >
> >> At the risk of running this subj. in the ground,
> let me ask
> >> one more question.
> >> What governs the capacitance/voltage spec?of the
> line
> >> bypass capacitor? I have several Hammarlund?
> rcvrs?and the
> >> values vary from .01uf used on the HQ-100, 110,
> 150,?170;
> >> .05uf used on the HQ-120X & 129X and .022 on
> the
> >> HQ-140X. And the voltage ratings run from 500V
> (HQ-120X
> >> & HQ-129X)?to 1.4kv on the others.?Some of
> these rcvrs
> >> are similar, but they use diff. values. I assume
> >> the?capacitor voltage ratings used?were for DC,
> but
> >> substantial enough to handle 3 or 4 hundred vac
> (have never
> >> noticed any ac ratings for these capacitors).
> >>
> >> Tnx, Bill, K4JYS
> >
> >
> >
> >
> >
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