[TMC] Why GPR-90s Look So Good

Fri Dec 12 14:30:09 EST 2014

My thanks also to Woody!  And to the really interesting info about
"dynamic symmetry" from Richard.

Last thing any of us want to do is insult one our GPR-90's.   It's
liable to retaliate by making you replace the 3.95Mc xtal!  :)

It's quite possible that Ray de P was a subscriber to the dynamic
symmetry ideas, though the appearance of the earlier TMC rigs may have
come from one (or more) of the other contributors at the company, such
as Tony Bernardi (the chief engineer in the 50's).  Ray and the
various technical leads in the company were self-taught to an extent
that would be quite surprising today.  Most of them were hams and
learned much of their trade building things for fun.  Most also worked
at Press Wireless during WWII, right before TMC was founded.  I've
looked at the wartime PreWi transmitters, and I have to confess that I
don't see much resemblance.. the distinctive TMC design features--the
symmetry, finish, lettering, and so forth-- just aren't there, though
the PreWi rigs were not bad looking!  You can maybe see some hints of
TMC design characteristics in some of PreWi's lesser equipment, such
as the RTTY adapters.   Let me see if I can track anything down..

Another historical note that some of you might find interesting.. many
have noted the similarities between the GPR-90 and the HQ-180 from
Hammarlund.  As it happens, Les Norde, who was the cheif receiver
architect at Hammarlund during the HQ- era, spent about 6 months or so
at TMC while 'between jobs', and just before joining Hammarlund.  He
appears to have been the principal designer of the AO-100, the
frequency generating mechanism that was used in the PMO, VOX, and
their kin (in production up through the 80's!).  This little gizmo is
part of an oven-stablilized LC oscillator with a cam-corrected
variable capacitor as its linearly variable frequency source.
Evidently Les had many discussions with others at TMC about receiver
design while he was there, and that's probably the reason that there
are some similarities between the radios..  Many thanks to Don Toman,
who told me about all this.. he was an "intern" at TMC while in high
school in 1951-52, and worked closely with Les.  Don, then (and
possibly still) the youngest-ever DXCC, found that he had much in
common with Les.. :)

Cheers,
jp

On Fri, Dec 12, 2014 at 1:50 PM, Chris Kepus <ckepus at comcast.net> wrote:
> Whew.
>
> As this conversation developed, it seemed certain that the facts were
> proving TMC failed to hit the Golden Ratio when designing the 90.  As a
> result, I've been consoling my 90 that she still looks great to me, no
> matter what.  Now, this morning, I can go out to the shack with a smile on
> my face and give her the good news.
>
> Woody...thanks from the both of us...from the bottom of my heart to the
> center of her beautiful knobs!!! ;-)
>
> Merry Christmas and Happy Holidays to all the TMC'ers!
>
> Chris
> W7JPG
>
> -----Original Message-----
> From: TMC [mailto:tmc-bounces at mailman.qth.net] On Behalf Of Woody Demitz
> Sent: Friday, December 12, 2014 8:38 AM
> To: John Poulton
> Cc: tmc collector's group
> Subject: Re: [TMC] Why GPR-90s Look So Good
>
> Thanks, John.  I viewed the jpg of the GPR-90's front panel and tried
> various measurements.  As my research model, I chose "Vern" the
> snaggle-toothed muffler repair guy in the Aamco TV commercial of years ago,
> who grins compellingly at the potential customer and says, "We don't have
> your exact muffler, but we''ll make it fit." Methodology: hold metal tape
> measure up to IPad screen and try to avoid scratching screen, while taking
> rough reading of various potential golden rectangles on panel. Result: Utter
> failure, until I decided to work the problem. Instead of using L=width of
> the inset holding the freq dials and H=distance from bottom of the two
> tuning knobs to top of inset, which yielded a disappointing 1.4:1 ratio, I
> redefined "H" to begin not from the bottom of the freq tuning knobs,
> but--and this is brilliant--from the CENTER of those knobs. My theory being
> that the human eye is drawn not to the outside rim of those knobs, but to
> their center. This yielded a much more sa  tisfying ratio of 1.68.  Not
> quite the perfect 1.618, but hey..
>
> 73,
> Woody KO3S
>
>
> Sent from my iPad
>
> On Dec 10, 2014, at 10:09 AM, John Poulton <jp at cs.unc.edu> wrote:
>
>> You can measure the proportions yourself, without needing an actual
>> GPR-90 in front of you.  There are some 'hidden' parts of the
>> TMCHistory website that you can easily get to that have beautiful b/w
>> photos of many of TMC's products.  See, for example,
>>
>> http://tmchistory.org/tmc_tables/rig_pix_db/gpr-90/
>>
>> I'll get them all linked eventually.. :)  The front panel of the
>> GPR-90 is much wider than the Golden Ratio, about 2.15:1, and the
>> tuning dials and central controls are a bit less at about 1.4:1.
>>
>> It's not really possible to get a rack-mountable item's front panel to
>> conform to the Golden Ratio exactly, since its width is always 19" and
>> height is some multiple of "U" (1.75").  A 'perfect" front panel would
>> be somewhere between 6U and 7U, I suppose...
>>
>> The GPR-90 is particularly handsome, but the reasons are
>> subtle--something about the symmetric layout of controls and the
>> proportions.  Maybe the Golden Rectangle is hiding in there somewhere,
>> but it's not obvious where.
>>
>> That said, most of TMC's products were elegantly designed and pleasing
>> to the eye.  The internals were built to extremely high standards, and
>> the equipment worked very well and was extremely reliable, thanks to
>> conservative design.  All of these aspects are, I think, what
>> attracted us collectors to TMC rigs, and the reason so many of these
>> beautiful machines are still on the air.
>>
>> There's just something about TMC's 'look' that can shout to you all
>> the way across a crowded hamfest.. :)
>>
>> 73, John K4OZY
>>
>> On Wed, Dec 10, 2014 at 8:48 AM, Woody Demitz <wdemitz at verizon.net> wrote:
>>> Some proportions are inherently pleasing to the eye. The Greeks and
> Romans knew this, and that is why at least some of their buildings remain
> beautiful to the eye, even in ruins. The principle the ancient architects
> followed has many names--the Golden Ratio, Golden Section or Divine
> Proportion--but it had to do with the ratio of the length of the rectangle
> formed by the building to its height.  The ratio is 1.6180339887.. (Thank
> you, Wikipedia). The ratio can be applied to pictures as well , and that
> suggests that perhaps the agreed-to-by-all beauty of a GPR-90 front panel
> may benefit from the same design principle. I suspect that the perceived
> pleasing rectangle need not be the full panel, but the rectangles formed by
> its component parts as well--for example, the frequency dials plus tuning
> knobs.
>>>
>>> Or maybe I've had too much coffee this morning. Perhaps someone who owns
> a GPR-90 can test the theory.
>>>
>>> 73,
>>> Woody KO3S
>>>
>>>
>>>
>>> Sent from my iPad
>>>
>>> On Dec 9, 2014, at 2:18 AM, "Richard Knoppow" <1oldlens1 at ix.netcom.com>
> wrote:
>>>
>>>>
>>>> ----- Original Message ----- From: "w1nzr via TMC"
>>>> <tmc at mailman.qth.net>
>>>> To: "Francesco Ledda" <frledda at att.net>; "Nick England"
>>>> <navy.radio at gmail.com>
>>>> Cc: "Mike Durff" <mike at oldaudio.net>; "tmc collector's group"
>>>> <TMC at mailman.qth.net>
>>>> Sent: Monday, December 08, 2014 6:33 PM
>>>> Subject: Re: [TMC] Why ?
>>>>
>>>>
>>>>> A lively, erudite and enjoyable discussion.....as long as you are a
>>>>> radio geek...thanks all...
>>>>>
>>>>> Brown Beezer
>>>>  This is an unusual list because we have a couple of real historians on
> it who have done a lot of digging of the sort not often found John Polton is
> perhaps the main contributor since he has befriended the family who owned
> TMC.  There is also something peculiarly attractive about TMC products, hard
> to say what. For instance, the GPR-90, which is, frankly, only a medium-good
> receiver, is one of the best looking and feeling ever.
>>>>
>>>>
>>>> --
>>>> Richard Knoppow
>>>> Los Angeles
>>>> WB6KBL
>>>> dickburk at ix.netcom.com
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