[Hammarlund] Old Hammarlunds - modifications.

Thu Apr 14 13:30:55 EDT 2011

After I get my 400 up to stock specs I intend to do a few front end mods 
using octal tubes as I dont want to be stuck with it on 40M and below with 
the noise generators. Kens triode detector suggestion bears investigating as 
there is life after AM (-;

No ham requires 12-16W PP audio unless its to impress visitors but I wont be 
changing it much except to reduce plate dissipation below boiling water 
levels. Most used 6F6's and 6V6's Ive tested on the Hickok 752A have leakage 
which will cause some distortion if its minor to even more distortion and 
dissipation if its excessive. I put those on fleabay for the audiophools and 
guitar freaks.

These days more of us have lab grade test equipment and a much higher 
understanding of what really works than even 20 years ago at the dawn of the 
Internet.

Carl
KM1H

----- Original Message ----- 
From: "Todd, KA1KAQ" <ka1kaq at gmail.com>
To: <kgordon2006 at frontier.com>
Cc: <Hammarlund at mailman.qth.net>
Sent: Thursday, April 14, 2011 12:53 PM
Subject: Re: [Hammarlund] Old Hammarlunds - modifications.

> On Thu, Apr 14, 2011 at 12:00 PM, Kenneth G. Gordon
> <kgordon2006 at frontier.com> wrote:
>> A kind soul on this list sent me zipped copies of three articles from CQ
>> magazine detailing modifications to the Super Pro. These are the Geissler
>> article from 1957, the Lee article from 1958, and the Reed article from 
>> 1961.
>>
>> ALL of these are rather extensive, and NONE of them seem to me to be
>> totally necessary.
>
>
> I think the time in which these articles appear indicate more about
> the mods than anything. Back then, not many hams had a choice of the
> plethora of gear we have today and instead had to make do with
> whatever would fit their budget. There were a lot of surplus Super
> Pros kicking around along with the BC-348, Command set/ARC-5s, and so
> on. Wasn't around until the newest article was published, so I can't
> say for sure but my guess would be that you did whatever you could to
> upgrade/improve whatever you already had or could afford to buy.
>
> Referring back to Henry Rogers' page on the Super Pros under
> 'Modification Mayhem', a number of these modifications seem to address
> problems that were related more to user issues than actual design
> deficiencies, or desires to somehow make a late 1930s radio into a
> newer set:
>
> "L. E. Geisler Modifications - With the cheap, easy to find
> availability of the surplus WWII Super-Pro receivers in the
> mid-fifties and sixties, the "modification mania" did finally catch up
> with the line and the WWII Super-Pro was considered "fair game" for
> modifications. Most of the infamous Super-Pro modifications were
> derived from the first of the series, "Souping the Super Pro" by L.E.
> Geisler, published in the Dec.1957 issue of CQ magazine. Geisler was
> an engineer that worked out of Japan for a company that sold modified
> Super-Pro receivers. Today, Geisler's modifications are "tame" and
> basically replace the 6L7 mixer tube with a different octal mixer tube
> that is quieter, then he replaces all of the capacitors and does a
> full alignment - pretty much standard stuff. Geisler's mods are
> conservative, make sense, improve performance and do no real harm to
> the receiver. One has to remember that Geisler's company sold these
> modified Super-Pro receivers so they had to perform better yet still
> retain the professional-commercial appearance in order to have
> marketability.
>
> Post-Geisler Modifications - The later modification articles
> endeavored to "out-do" Geisler's "makes sense" conservative approach
> with more and more outrageous modifications. Included in the list of
> notorious "cut and hack" articles are "A Super 'Super-Pro'" and
> "SSBing the Super Pro" - both published in the "Surplus Conversion
> Handbook," part of the CQ Technical Series. These articles advocate
> the wholesale modification (destruction) of the entire receiver,
> including replacement of the front-end tubes with miniature tubes, an
> on-board solid-state power supply, removal of the 14 watt P-P audio
> section to install an anemic 6AQ5 single ended audio section (which
> also then provided room for the on-board power supply,) on-board
> converters to cover 10 and 15 meters, product and infinite impedance
> detectors - on and on. It's doubtful that a receiver could ever be
> returned to original after being the victim of these later
> modifications. I have only seen a couple of Super-Pros that attempted
> these modifications and they were wrecks. No doubt, the end product
> failed to impress the owners and the receivers were afterward
> relegated to the junk pile."
>
>
> While it probably made sense at the time, in today's world with so
> many 'better' options(if that's one one seeks) available with new
> sets, it seems like a lesson in futility. But since there are already
> so many hacked up versions out there, we have plenty of opportunity to
> investigate that side, too.
>
> I sold one of these sets years ago that had every octal replaced with
> miniature tubes. It looked like an empty box. A fellow in MA has
> converted one to all solid state devices. It looks even worse! I
> currently have two pre-war SX models which have both been hacked to
> some extent. I'm hoping to restore at least one of them back to all
> octal tubes, replace the other bad components, and go from there.
> Unfortunately, it's never easy to figure out someone else's ideas
> involved, especially when they never completed the mess!
>
> The ones with the onboard power supply and hacked out audio are
> horrendous. I always remind myself that it was someone else's radio
> and I can't appreciate why they did it since I wasn't there. I try to
> respect the role that surplus gear and amateur mods played in our
> hobby decades ago, it's just that some of them seem to make so little
> sense for the work involved.
>
> ~ Todd,  KA1KAQ/4
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