[Hammarlund] Old Hammarlunds

[Carl]

When a SP-200 can compare with a 1937 NC-101X or a 1939 NC-200 for drift 
then I might get one again. They both also have great PP audio.

Meanwhile I'll see what that $20 SP-400 from Nearfest will do as its close 
to being finished....need an S meter glass however.

Its a shame Hammarlund never offered a good sounding external speaker, at 
least the ones in the console versions of the Comet and Super Pro did them 
justice. I use mostly Hallicrafters speakers with a few 10" Nationals in the 
mix.

Carl
KM1H


----- Original Message ----- 
From: "Todd, KA1KAQ" <ka1kaq at gmail.com>
To: <djed1 at aol.com>
Cc: <Hammarlund at mailman.qth.net>
Sent: Tuesday, April 12, 2011 1:44 PM
Subject: Re: [Hammarlund] Old Hammarlunds


> On Tue, Apr 12, 2011 at 11:23 AM,  <djed1 at aol.com> wrote:
>
>> Just to show how the technology changed, my SP-600 drifted about 12 KHz 
>> from a cold start, and the R-390A drifted 0.4 KHz.
>
> And that really is a big point that many seem to miss. The original
> Super Pro 200s were a 1939 design that evolved from the earlier SP-10
> and -100 models. It's important to keep in mind things like the higher
> bands weren't the big draw then that they are now. In fact, the
> standard Super Pro covered the BC band to 20 mc only. Only the SX
> model, made in much lower numbers, added coverage through 10 meters at
> the expense of much of the BC band. Compared to other radios of the
> day, the Super Pros were at the top of the pile with the HRO, They
> were used through WWII virtually unchanged other than some power
> supply upgrades.
>
> A lot changed over the roughly decade and a half since the the SP-200
> series was introduced. The SP-600 is an entirely different beast, a
> Super Pro in name only. And the R-390 series with the famous Collins
> PTO was and in many ways, still is the benchmark for old tube
> receivers. Which is why it's important to keep things in perspective
> with respect to things like drift, features, and so on.
>
> As Ken mentions and as the manual states, the receiver was designed to
> be left on for extended periods to stabilize. It takes a while to
> bring all of the mechanical bits into harmony, so to speak. Once it
> stabilizes though, it's as solid as a rock. Having the receiver in a
> location where it can experience temperature changes (near an outside
> door, for example) or fluctuating line voltage wouldn't be desirable.
>
> For anyone who hasn't seen Henry Rogers' great site yet and would like
> to read more on the Super Pros, I highly recommend it:
>
> http://www.radioblvd.com/hammarlund_super_pro.htm
>
> Henry outlines many of the issues (operator-generated, in many cases)
> that have given them a bad rap over the years. I can verify his
> findings, especially using the correct feedline impedance for low
> noise operation.
>
> The only trick is bringing them up to spec and using them as designed
> and detailed by the manuals. Known primarily as a workhorse, they are
> really more the thoroughbred of their day. I love my early Super Pros,
> they are some of my favorite receivers. In fact, I use a 1937 SP-100
> as a bedside receiver driving a large Jensen speaker in an EV
> enclosure. Apparently I'm extremely lucky, as it shows no appreciable
> drift from turn on to 3-4 hours or more later.
>
>
> ~ Todd,  KA1KAQ/4
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