[ARC5] NC-270 Success

[Richard Knoppow]

     Both of my speakers are identical to the one shown with the 
HQ-129-X I can't see the one with the SP-200-X well enough to be sure 
about the grill. The desk cabinet is the standard one offered with the 
receiver. There are ads for the SP-200 showing a box like ours but with 
horizontal chrome strips to match the desk cabinet on your receiver. 
Hammarlund offered a couple of variations of speakers over the life of 
the Super-Pro. The earlier ones, I think the SP-110, had a connection 
for a field coil speaker. This was eliminated in the later models. They 
were also offered with either 10" Jensen or 12" Rola speakers but no 
cabinet.
    I looked at a couple of old Bud catalogs and the Bud listing in a 
1948 "Radio's Master", the cabinets have different grills than the cane 
metal on ours. I know my boxes are Bud because they have Bud labels on 
the bottom.
    My original station receiver was a BC-779. It is a very good 
receiver. Stability can be improved by adding a temperature compensating 
capacitor across the LO oscillator. This was done on the SP-400-X. Small 
value cap, maybe 5pf but as large a positive TC as you can find. Also, 
my receiver pulled with RF gain. I cured that by adding a 150V voltage 
regulator tube. The tube is connected to the LO. The plate resistor of 
the LO is changed to 12K. The Super Pro is extremely well shielded and 
has almost no spurious responses other than one image and that is fairly 
far down.
     There is a military handbook but I can't remember its number that 
is a survey of communications equipment c.1945. It shows charts of the 
spurious responses of several receivers including the Super-Pro and the 
SX-28. The Super-Pro has only the image response, the SX-28 chart looks 
like a corn field.
    FWIW regenerative and super regenerative receivers are nothing to 
sneer at.
On 12/10/2016 7:52 PM, Rich Post wrote:
> Hi Richard and the list,
>
> To answer your questions, the Hammarlund HQ-120 and 129 speakers may
> indeed have been made for them by Bud.   One of my SP-200 radios resides
> in a Bud rack cabinet with the chrome stripes. Your chrome stripe
> speaker might be a match.
> <http://www.ohio.edu/people/postr/bapix/SP210bk.htm>
>
> There are variations in speaker grille pattern, but I don't know how
> that relates to date of manufacture if at all.  Compare the grille of
> the one next to my  HQ-129 compared to the one on the HQ-120 page.(link
> to HQ-120 is on the 129 page)
> <http://www.ohio.edu/people/postr/bapix/HQ129.html>
>
> For sensitivity, I do indeed have the ability to measure signal to noise
> ratio but mostly when I mention performance and sensitivity on my
> website, it is subjective.  Especially since I am mostly dealing with a
> sample of one, no general judgment can or should be made.  Like many of
> the folks on this list who have quite a few receivers to compare with
> including some very nice modern ones, a subjective judgment can be
> useful.  For example, I mention 6 meter performance on the NC-270 and
> that my superregen Heath Lunchbox can outperform it in sensitivity.  If
> other owners of the NC-270 have better results on the 6 meter band, let
> me know.   My experience might be unique.
>
>  I prefer to leave my radios restored but stock if at all possible, the
> main exception being for safety, so my subjective judgments are not
> based on "hopped-up" receivers.
>
> Wishing you and all others on the list great DX and lots of joy this
> Christmas,
> Rich KB8TAD
>
> On Sat, Dec 10, 2016 at 5:38 PM, Richard Knoppow
> <1oldlens1 at ix.netcom.com <mailto:1oldlens1 at ix.netcom.com>> wrote:
>
>        I looked through your site, lots of interesting stuff there.
>        You mentioned the speakers supplied for the Hammarlund HQ-120-X
>     and other receivers. AFAIK the cabinets were stock Bud items. I have
>     a couple with Jensen speakers in them. The cabinet color varies. I
>     think they may have offered them in bulk to manufacturers with
>     special finishes. I have a couple of old Bud catalogs, they show a
>     similar cabinet with chrome stripes running vertically. Hammarlund
>     seems to have offered the same cabinet, with horizontal chrome
>     strips for the Super-Pro receivers. Those seem to have been sold
>     with unmounted speakers, either Jensen or Rola.
>        Bud made a large variety of cabinets of various sorts and
>     undoubtedly changed the details of the styling on occasion. I have
>     other speaker boxes with Bud labels on them but of different style
>     from the rounded corner ones sold for Hammarlund.
>        Another thought that has nothing to do with speakers:
>        When you speak of sensitivity what exactly are you measuring?
>        Manufacturers specified different techniques, some of which are
>     useful only for determining if the gain is normal. Sometimes people
>     plug similar tubes into the RF stages and find they make the sets
>     "hot" but never measure signal to noise.
>     --
>     Richard Knoppow
>     1oldlens1 at ix.netcom.com <mailto:1oldlens1 at ix.netcom.com>
>     WB6KBL
>

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL