[AMRadio] 220 vac line

[Mahlon Haunschild]

Pete/Paul, that's correct; a Thunderbolt properly wired for 220/240V 
does have hot/hot/neutral on the plug, but unfortunately, the neutral is 
internally connected to the chassis,  It would be best to break this 
connection in the interest of safety and then connect the chassis to ground.

The old Henry amplifiers indeed all had dual-voltage transformers and 
the blower was 117/125V, necessitating a neutral connection just for the 
blower.  Silly, that.  At least neutral wasn't connected to the chassis, 
but I may be wrong on that (I sold the amplifier long ago).

As an aside, 14 AWG or 12 AWG SJ/SJO 4 wire cordage (not CL2, which is 
not rated for 240V) is hard to find.  The only place I've ever found it 
at retail is Skycraft in Orlando.  The local electrical supply outfits 
blew me off.

regards,

Mahlon - K4OQ


> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 27 Jul 2011 08:50:33 -0400
> From: manualman at juno.com
> Subject: Re: [AMRadio] 220 vac line
> To: amradio at mailman.qth.net
> Message-ID:<20110727.055110.989.1480699 at mailpop09.vgs.untd.com>
> Content-Type: text/plain; charset=us-ascii
>
> I believe they did the same thing with the Johnson Thunderbolt and KW
> amplifiers.
>
> Pete, wa2cwa
>
> On Wed, 27 Jul 2011 07:55:19 -0400 "Paul Christensen"<w9ac at arrl.net>
> writes:
>>> Electric kitchen ranges with 3-wire plug run on 240V, with the
>> neutral and
>>> ground bonded together.  So does the BC1-T broadcast transmitter
>> in
>>> original
>>> configuration.
>>
>> And, so does the Alpha 70 and 77 series of HF amps -- along with
>> some of the
>> big Henry models.  In the case of each amp, neutral is used to run a
>> 120VAC
>> blower.  In the Alpha 70/77 they made it easy to separate neutral
>> from
>> chassis ground by cutting a jumper on the Cinch-Jones power plug.
>> The
>> change doesn't even occur inside the amp.  I ran 4-wire, #8 AWG
>> between the
>> panel and the shack, terminating into a 30-amp twist-lock
>> receptacle.  My
>> only dilemma is that I have one receptacle and four amps, requiring
>> a
>> physical change of the power plug when changing between amps.  No
>> really
>> good solution comes to mind, mostly for convenience reasons.
>>
>> At the time these devices were manufactured, it was acceptable to
>> join the
>> chassis to the neutral connection.  40+ years ago, the NEC may have
>> strictly
>> forbidden this practice, but the NEC is a premise wiring standard --
>> not a
>> products wiring standard.  So, perhaps the root of this really goes
>> back to
>> what was allowed  under UL guidelines at the time.  Well after 1970,
>> the
>> manufacturers seem to have gotten the idea and had found a means to
>> better
>> utilize the blower between 120VAC and 240VAC service.
>>
>> Paul, W9AC
>