There is a good discussion of the power supply in the 2K4 here about
half way down.
http://www.qsl.net/i0jx/supply.html
73, Dan, N5AR
Steve Katz wrote:
> The Henry amps I've had (several over the years) when operating properly
> produce negligible hum modulation at full rated power.
>
> But I asked earlier if he found the same evidence of ripple when he used "CW"
> (vs. "AM") on his exciter and I don't think I've seen that answered.
>
> If "yes," then it could well be a PS issue in the Henry; if "no," then it's
> something else. Usually if the PS develops unreasonable ripple, its
> regulation will also suffer since they're both based on the same factors.
>
> Steve WB2WIK/6
>
> -----Original Message-----
> From: amps-bounces@contesting.com on behalf of TexasRF@aol.com
> Sent: Thu 2/18/2010 5:34 PM
> To: johndtate@post.com; amps@contesting.com
> Subject: Re: [Amps] 120 cycle hum from Henry 2K-4
>
>
>
> John, every dc power supply has some ripple. If the power supply has a
> nominal output of 2500vdc and the ripple voltage is 125 vpp then that would
> be
> 5% peak modulation or 3.5% rms. I think this is 20log .035 or 29 dB below
> the carrier in this case.
>
> So, how many dB down do you think your hum level is?
>
> I don't know how to calculate ripple on a Henry type power supply; perhaps
> some here knows how or has actually measured one.
>
> 73,
> Gerald K5GW
>
>
> In a message dated 2/18/2010 5:31:28 P.M. Central Standard Time,
> johndtate@post.com writes:
>
> I just acquired a Henry 2K-4 console linear amplifier. I like to run
> AM as well as the other modes. The Henry is rated for continous duty
> and as AM is closer to continous than SSB, I figured it was a good amp
> to have. I'm very satified with the output from the two aging Eimac
> 3-500Z's but the 120 cycle hum that rides on the carrier is
> troublesome. It's there whether I'm using my Kenwood TS-570 or my
> modified Heathkit DX-60 to drive it. When I use the DX-60 (which I
> prefer for AM) making adjusting the tuning control will change the
> amplitude of the hum but never reduce it enough. Seems like when in
> resonance the hum peaks too. I have grounded the amp and the DX-60 via
> 10 gauge solid copper to an 8 gauge solid copper coming into the shack
> that's attached to the 8 foot copper clad steel ground rod right
> outside a couple feet away.
>
> For some perspective, I have no audible hum from the Heathkit SB-200
> and everything else the same. The SB-200 is setup for 120 volts
> however, not 220/240.
>
> The Henry has full-wave bridge rectifier then uses an 8 henry (700ma)
> filter choke with an oil filled .1mf (7500v) in parallel then an oil
> filled 20mf (5000v) cap to ground.
>
> I've been told those oil filled caps rarely go bad and usually last
> longer than we do. Any clues where I should be looking to solve this
> hum problem? Of course it's not really noticible on SSB but I'm sure
> it's in there as well.
>
> 73 and thanks for any tips and patience with this !
> John KX5JT
>
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