[HBR] Current day HBR

[Peter Bertini]

Mental exercises are fun. I was even mulling having the radio being
able to switch between double conversion and single conversion for
stuff like 160 meter coverage, and for BCB coverage using the dual
purpose tuning capacitor system mentioned earler.

If I ever get mine started, I will be using the half lattice filters
salvaged from a few defunct HR-10s in the first IF.

I can hear the gasps now :) :) Ducking for cover...


Pete

Pete

On 1/10/11, Shoppa, Tim <tshoppa at wmata.com> wrote:
> Walt writes:
>> Adding general coverage by means of an alternate set of coils that
>> connects additional tuning capacitance (the 3-gang AM/FM cap
>> previously described) won't yield a top grade general coverage
>> receiver. For one thing, general coverage receivers with mechanical
>> tuning need major attention to the tuning rate. A GC functioning
>> version of an HBR will be very tough to use on GC SSB signals, even if
>> it's fine on the ham bands.
>
> Thing is, I'm not sure that in general a new tuning capacitor is necessary.
>
> I haven't completely reverse-engineered the SWL-oriented HBR
> coilset that I inherited, but each coil set nicely covers a SWL band.
>
> Note that the HBR coilset design allowed for varying ratios of
> bandspread/bandcenter ratio using several well known strategies.
>
> The bandspread ratio is nicely set by the coil taps/fixed cap/variable
> cap in each coil and seems to be adequate for a typical SWL band
> plus some margins on each end. And each SWL band is, realistically, not
> too awful broader than a ham band.
>
> I would be hard pressed to come up with a good reason for a SWL coilset
> That covered two different SW bands. Maybe 16M and 19M on the same coilset.
>
> I look at other ham+SWL receivers of the era - the Drake 2B (got SWL
> Using ham band crystal images, or with custom crystals, and there was
> LOTS of room for custom crystals and a lot of SWL's used 2B's)
> or later the Heath SB-303 nee SB-313 and that seems like the
> right level of "general coverage" to me (while not truly being
> general coverage in the derogatory sense I otherwise use it!)
>
> Tim N3QE
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