[Amps] Subject: Henry hum on transmitted signal

[gudguyham at aol.com]

Steve, I won’t mention any names, but somebody bought quite a few Henry amps and stripped out the ENTIRE power  supply guts, plate transformer , choke, HV cap, and the tuning caps  even the wire would step start gizmo.  Sold off all that stuff and put in a cap input supply using PD transformer like Ilona the big Ameritrons.


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On Tuesday, September 5, 2023, 5:26 PM, Steven Katz <stevek at jmr.com> wrote:

Lou, I've seen that, too.

I've also seen the resonating cap short out (choke is still fine) and B+ soar to 6kV and they just keep operating.

Something will eventually fail, but those big oil-filled caps can often handle 6kV for quite a while, and so can the tubes in many cases.

-----Original Message-----
From: Amps <amps-bounces at contesting.com> On Behalf Of gudguyham--- via Amps
Sent: Tuesday, September 5, 2023 4:24 PM
To: Rob Atkinson <ranchorobbo at gmail.com>; amps at contesting.com
Subject: Re: [Amps] Subject: Henry hum on transmitted signal

Rob, it seems as though is not “if” but “ when” the choke craps out in those Henry amps.  I’ve seen where many chokes shorted to the core and guys mounted the choke on insulated material instead of getting a new one. Lou


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On Tuesday, September 5, 2023, 7:14 AM, Rob Atkinson <ranchorobbo at gmail.com> wrote:

I think the resonant choke design is clever by a half.  It's just too finicky and failure prone for my liking.  Also, I've seen a choke Henry used in one of their amps, I forget which one but it was supposedly rated for 700 ma.  I have  a 700 ma filter choke out of a 1 KW broadcast rig intended to run continuously and it's at least twice as big and heavy as the dinky thing Henry used.  I've seen I don't know how many RF power amplifiers designed for volatile loads like SSB and CW and they did fine with nothing but around 40 mfd capacitance for a filter.  I would only use a choke input for power supplies serving transmission modes that put the supply under continuous load, such as AM and RTTY.  I would rebuild that power supply for whatever xmission mode is intended and ditch that resonant choke scheme.

73

Rob
K5UJ
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