[ARC5] Parts needed for ARC-5/274-N - splines...

Mon May 26 21:12:44 EDT 2014

The studio mike stands are 5/8-27,  http://www.radioshack.com/product/index.jsp?productId=2131024#stuff-you-want. “It just so happens” this is the same size and thread used on the ARN series. It’s also the size Heath used on a lot of older test gear and is the same size used with single button microphones. Greedbay usually has an assortment of odd and ends to play with rather cheaply. Another lucky stroke is the male part of the connecter will mate to the “cup” that surrounds the male pin on BNC, TNC, N and perhaps mini UHF coax adapters. Excellent use for those junkers occupying space in the shack.

1/2 27 taps can be bought on greedbay for what I think is a rather reasonable price. They’re Chinese even when sold by US sellers. I got one and am well satisfied. The harder job is finding the right drill, I just went a bit bigger and it worked for my purpose.

eBay item number:
230839361905

I hauled my late father’s Machinery’s Handbook 0f 1940, 10th ed., off the shelf and found a nice history of machine screw standards. Wood screws too in another section. Sadly, it’s not to be found in the 13th ed. of 1946. What inspired this journey through history was my decision to sort my boxes of unsorted nuts and bolts. Some seemed to fall in the cracks nor were they metric. Problem solved. Anyone need some # 14 bolts? Shank measures 0.242” - 20 tpi. I got em.

From: J. Forster
Sent: ‎Monday‎, ‎May‎ ‎26‎, ‎2014 ‎6‎:‎01‎ ‎PM
To: AKLDGUY .
Cc: arc5 mail list

Very unlikely,IMO.

Mike, is the outer thread the same as is used on studio mike stands. I ask
because pipe threads are almost universally tapered, but electrical
threads are not.

-John

================

>> ...since the thread is actually 1/2-27.  1/2-28 makes an interference
> fit, and with fresh aluminum to aluminum contact
>> may weld the two parts together through galling action.  I'm not sure
>> how
> the powers that be, or were, came up with the
>> odd thread count per inch, as I discovered for the flex cable article on
> my website that the 27 T.P.I. thread came from
>> a 19th century standard for gas light fittings! It persisted in
> electronic hardware in a number of places, including coax
>> microphone connectors with the center soldered button.  You can buy a
>> tap
> with that thread, but it counts as a "special
>> thread" that is more expensive.
>
> Any chance that the thread is British/Euro?
> Many decades ago I scouted around the hardware stores and vehicle parts
> stores here in Auckland and found a pipe fitting that could be screwed on
> by hand, so the threads were either identical or very close.
>
> The fitting was of brass and of the type that connects fuel line to
> carburettor in vehicles. I can't remember whether I had to drill out the
> hole or not, but do remember that the shaft was eventually a snug fit
> inside it.
>
> Since we in the still subservient (-; Brit colonies tend to have more
> Brit/Euro stuff, maybe the thread was Brit/Euro?
>
> 73 de Neil ZL1ANM
>
>
> On Tue, May 27, 2014 at 8:06 AM, Mike Hanz <aaf-radio-1 at aafradio.org>
> wrote:
>
>> On 5/26/2014 1:55 PM, hwhall at compuserve.com wrote:
>>
>>> Tom Kneitel's Surplus Conversion Handbook, 1970 edition, had a short
>>> note
>>> on an ARC-5 RX tuning adapter that seemed the best I've seen. It
>>> provides
>>> mechanical support for the coupling joint, which seems to be key to
>>> getting
>>> a good feeling control and one that places minimal strain on the
>>> coupling
>>> material.
>>>
>>> It requires making a short (3/4 inch) cylindrical fitting of brass or
>>> aluminum (could probably do it in modern hard plastics or composites,
>>> too),
>>> drilled & tapped 1/2 - 28 at one end to screw onto the RX tuning ring,
>>> with
>>> a 1/4 inch hole continuing through the other end. Making that is the
>>> hard
>>> part.
>>>
>>
>> Trudat.  :-)   Tom must have misread his thread gauge as well, since the
>> thread is actually 1/2-27.  1/2-28 makes an interference fit, and with
>> fresh aluminum to aluminum contact may weld the two parts together
>> through
>> galling action.  I'm not sure how the powers that be, or were, came up
>> with
>> the odd thread count per inch, as I discovered for the flex cable
>> article
>> on my website that the 27 T.P.I. thread came from a 19th century
>> standard
>> for gas light fittings! It persisted in electronic hardware in a number
>> of
>> places, including coax microphone connectors with the center soldered
>> button.  You can buy a tap with that thread, but it counts as a "special
>> thread" that is more expensive.
>>
>>
>>
>>  A 1/4 inch dia short shaft extension goes in with enough length to
>> touch
>>> the spline shaft when installed, and a piece of plastic tubing makes
>>> the
>>> coupling from shaft to spline (could use brass or copper, too, I
>>> suppose).
>>> Then just attach your favorite knob to the 1/4 shaft.
>>>
>>
>> In a way, it is simply a home brew variation of the retention nut part
>> of
>> the command receiver local control at the bottom of http://aafradio.org/
>> garajmahal/flex_drive_cables.html
>>
>> It is certainly a more sound way to make the connection than having the
>> shaft cantilevered out from the tuning capacitor.
>>
>>     73,
>>  - Mike
>>
>>
>> ______________________________________________________________
>> ARC5 mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/arc5
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:ARC5 at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:ARC5 at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html