[ARC5] ARC-2 Information

[Tom Lee]

Hue,

Sorry, but you're simply wrong about this. I am speaking from direct 
experience. Only two wires power up the classic AA5. No such thing as a 
distinction between ground and a chassis. You are confusing later safety 
practice with decades of history that preceded three-wire power cords.

See, for example, 
http://www.angelfire.com/electronic/funwithtubes/AA5-1.html.

Or the wikipedia entry on the AA5.

--Tom

-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 9/6/2020 19:06, Hubert Miller wrote:
> I don't think so. From the 1940s at least, there was a "ground" and a chassis, with some capacitor like 0.05 mFd connecting the two.
> The Regressive Edu-Kit really surprised me. I have the manual and the kit, and I don't recall a word of warning that your headphone wire
> could with a flip of coin, be AC hot. When I first saw the Edu-Kit manual, I saw the 3 wire line cord and first thought it was wired for safety,
> but one wire was just a resistance.
> BTW, around 1985 I wrote an electronics magazine and asked if they should still be running Edu-Kits' ads with the testimonials from 1947
> customers. I also questioned the usefulness  of the  1985 Edu-Kit suggestion that printed circuits were the up & coming thing.
> The magazine editor wrote me back ( this was in the Paper Age ) that Edu-Kits always paid their bill.
> I should have kept that letter with my Edu-Kit manual.
> I should also have kept the letter from Tom Kneitel telling me I didn't know enough to criticize and that he owned a Trans-Am and a boat
> and so there you go.
> -Hue Miller
>
>> I can attest to that! Having worked for several years in a TV/radio service shop in the early 1970s, I can verify that AA5s of that era always had the chassis hardwired to one side of the AC line. The nominal filament voltages added up to 121V for a reason. Classic problem was replacement of a frayed cord or bad plug by the consumer, who had a
> 50-50 chance of tying the chassis to the hot side of the line. Murphy guaranteed that I would only see that 50%.
>
> The Progressive/Regressive Edukits not only did the same thing, but with resistance wire to drop much of the line voltage to drive the filaments.
> My next door neighbor replaced the cord with a regular piece of zip cord. The result was much unhappiness.
>
> -- Tom
>
> --
> Prof. Thomas H. Lee
> Allen Ctr., Rm. 205
> 350 Jane Stanford Way
> Stanford University
> Stanford, CA 94305-4070
> https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww-smirc.stanford.edu%2F&data=02%7C01%7C%7Caee3a473249242a856c308d852d065ac%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637350402290408248&sdata=LgIJyeWWq%2BxrzaQA%2FPUHPfAP8CWohFAfn2plKNksZDI%3D&reserved=0
>
> On 9/6/2020 18:38, Scott Robinson wrote:
>> Actually, quite a  few AC-DC radios DID have their chassis wired to
>> one side of the line Some mid-30s examples are a horror--easily
>> touched live parts. Late _mid-fifties and on (Zenith, in particular),
>> did a very good job isolating the chassis in their AM-FM table radios.
>>
>> Since most small TVs had metal cases, I bet they are isolated.
>>
>> Scott Robinson
>>
>> PS-I hate AC-DC radios.
>>
>> On 9/6/20 6:08 PM, Hubert Miller wrote:
>>> Except: Scott, the machines with one side of the AC line connected
>>> directly to chassis were bottom end, such as the buzzbox welders
>>> advertised in magazines and kit radios for young people. (
>>> "Regressive Edu-Kit" was one ) TVs and radios did not have the
>>> chassis connected DIRECTLY to AC line.
>>> ONE ham rig did, I think SBE-13. I have one somewhere. Had a safety
>>> indicator lamp on front panel.
>>> -Hue Miller
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