[Hammarlund] HQ-145 Specs

[Richard Knoppow]

    I have somewhere, but can't find it, a military handbook of 
WW-2 vintage with detailed descriptions of various equipment. In 
it are charts showing measured spurious responses of several 
receivers. I remember the one for the Super Pro showed ONE image 
and nothing else while the chart for the SX-28 looked like a 
cornfield. I don't remember what other receivers were covered but 
that was pretty amazing. I used a BC-779 with and without a few 
modifications as my station receiver when starting out. It is an 
excellent receiver but drifts unless run all the time. I got rid 
of the voltage drift by using a VR tube on the local oscillator 
but there was still thermal drift. Hammarlund eventually put a TC 
capacitor in the LO in the last of the SP-400 line. One day I 
will get this receiver out of storage (my life seems to be in 
storage) and try the TC cap.
     I have never seen any specifications for performance for the 
Super Pro except in a couple of places in military manuals nor 
for other older Hammarlund receivers. I did see a spec for 1/2% 
calibration accuracy but mine was far better than that.
     Since the tuning capacitors in the 145 were made by 
Hammarlund my guess is that the calibration accuracy is at least 
as good.
     I think I said I was about to do some repair on my HQ-129-X 
and will see what I get when finished. Mine has a large error in 
the band spread calibration which I suspect is due to a defective 
resistor in the bandswitch. Easy to replace and I will report on 
what changing it does in the future.
    The Super Pro was probably the best receiver of its time and 
also the most expensive. I am not counting the RCA AR-88 because 
it was never commercially available. I have never seen a new 
price for them but suspect they must have cost about double what 
a Super-Pro did.

On 11/6/2019 8:20 AM, Dave Wood wrote:
> I have never seen detailed technician specs on the HQ-145 and I have looked
> many times.  I don't think Hammarlund started publishing meaningful specs
> until around the introduction of the HQ-170.  But what I've seen on the
> bench many times throughout the years is that the  145 on ssb hears about
> -116 DBM for 10DB S/N.  AM is around -104DBM.  On the highest band I
> usually see around -107 for SSB.  Note the sensitivity is reduced about
> 20DB on the BCB which I suspect was Hammarlund's way of dealing with the
> high level signals on the BCB.  Hope this helps.  73  Dave
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL