[Boatanchors] Did you ever wonder why?

Thu, 15 Apr 2004 18:18:42 -0500

Ray,

Not only no HQ 180, but none of the 200 or 300 series either.

I actually got carried away when I just wanted to return to my youth and get
an HQ 120 - which was my first real receiver.  (it was already 25 years old
in 1964!)  I would like to finish the collection with a 180, but still
waiting for the right one.  The others are all working fine.

Ed, W9EJB

----- Original Message -----
From: "Ray Friess" <[email protected]>
To: "Ed Berbari" <[email protected]>
Cc: "Philip Atchley" <[email protected]>; <[email protected]>
Sent: Wednesday, April 14, 2004 11:11 PM
Subject: Re: [Boatanchors] Did you ever wonder why?

> WHAT???  No HQ 180 in the collection?    HI HI
>
>
> Ed Berbari wrote:
>
> >Phil,
> >
> >I understand your lament about not having the antenna trimmer on many
> >receivers, but I would point out that in my entire collection Hammarlunds
> >(HQ 100,110, 120, 129, 140, 145, 150, 160, 170) that all of them have an
> >antenna trimmer.  For the most part these were not low end receivers in
> >their respective eras.
> >
> >Ed, W9EJB
> >
> >
> >----- Original Message -----
> >From: "Philip Atchley" <[email protected]>
> >To: <[email protected]>
> >Sent: Thursday, April 08, 2004 11:54 PM
> >Subject: [Boatanchors] Did you ever wonder why?
> >
> >
> >
> >
> >>Hi All,
> >>I was just sitting here listening to the Hallicrafters SX-71 and (as I
> >>
> >>
> >often
> >
> >
> >>do) musing over why engineers do things the way they do (as an
electronics
> >>technician I've worked with engineers in the past 8^)
> >>
> >>Yes, I know that bringing a new model (of anything) to market is
actually
> >>
> >>
> >a
> >
> >
> >>high wire balancing act of juggling present technology, ultimate
> >>performance, desired features, cost of production, parts availability,
> >>
> >>
> >"real
> >
> >
> >>estate" (room for components, heat dissipation etc), market demand and
> >>ultimately resale price and profit ratios.
> >>
> >>However, there is one control that isn't a really high priced feature,
nor
> >>difficult to implement, that I feel is very important in any receiver.
It
> >>has MORE OFTEN THAN NOT been left out by Hallicrafters, Hammarlund and
> >>others.  Oddly enough, this item is often included on lower end products
> >>like Heathkits, Knight Kits and others.  It will also be found on the
> >>military R-390x receivers but NOT on the top ranked Hammarlund SP-600.
> >>
> >>What is this lowly control?
> >>
> >>It's the variable capacitor in the first selective stage of the
receiver,
> >>THE ANTENNA TRIMMER.  As many readers of this list realize, switching in
> >>different antennas, each having different impedance's, reactance's etc
can
> >>drastically change the tuning of the input stage of the receiver.  It is
> >>almost guaranteed that except at one specific frequency, any given
antenna
> >>will NOT be a perfect match to the receiver, and often at no point on
the
> >>dial if you're using random antennas.
> >>
> >>1.  For stronger signals this won't make any difference in what you
hear,
> >>just what the "S" meter reads.  But on a very weak signal it can make a
> >>significant difference in whether you can copy the station or not.
> >>
> >>2.  For single conversion sets it can make quite a difference in overall
> >>image rejection too!  It probably makes some difference in image
response
> >>
> >>
> >on
> >
> >
> >>a double conversion set, but images aren't usually a big problem on
those
> >>sets.
> >>
> >>3.  I've found that on some sets, down in the tropical bands it can also
> >>help reduce QRM from the broadcast band.  (Though, for this task I find
> >>
> >>
> >that
> >
> >
> >>either a High Pass Filter with a cutoff above the broadcast band, OR
what
> >>
> >>
> >I
> >
> >
> >>use, a decent antenna tuner like one of the MFJ 300 Watt units having a
> >>larger Higher Q coil than receive only tuners.  That's because the usual
> >>"Tee" tuner makes a very effective High Pass filter.  I've found one of
> >>
> >>
> >the
> >
> >
> >>above antenna tuners can completely eliminate BCB QRM in the tropical
> >>bands).
> >>
> >>4.  While costs are always a factor in equipment design, the cost of the
> >>manufacture adding the antenna trimmer is actually very small, easily
> >>
> >>
> >offset
> >
> >
> >>by the additional performance that could have been realized.
> >>
> >>5.  IN FACT, this SX-71 has (to my mind) a totally useless tone control!
> >>The receiver already has so much selectivity (even in the normal
position
> >>
> >>
> >of
> >
> >
> >>the bandwidth switch) that audio is just a little muffled and has no
real
> >>highs to filter out with the "high cut" tone control.  That control is
> >>
> >>
> >left
> >
> >
> >>at the full treble position all the time.  An antenna trimmer would have
> >>been a better use of panel space and the small variable capacitor
probably
> >>only pennies more than the tone potentiometer.
> >>
> >>So, did you ever wonder?
> >>
> >>73 from the "Beaconeers Lair".
> >>Phil, KO6BB
> >>
> >>DX begins at the noise floor!
> >>Merced, Central California
> >>37.18N  120.29W  CM97sh
> >>
> >>_______________________________________________
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> >>** List Administrator - Duane Fischer, W8DBF/W9WZE **
> >>** For Assistance: [email protected] **
> >>$$ For vintage radio info, see the HCI web site $$
> >>http://www.w9wze.org
> >>
> >>
> >>
> >
> >_______________________________________________
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> >http://mailman.qth.net/mailman/listinfo/boatanchors
> >** List Administrator - Duane Fischer, W8DBF/W9WZE **
> >** For Assistance: [email protected] **
> >$$ For vintage radio info, see the HCI web site $$
> >http://www.w9wze.org
> >
> >
> >
> >
> >
>