[HBR] HR-67

[Helmut Usbeck]

Greeting,

I'm not to sure what you mean by a pre-mixer design?

I was thinking of using a 6BA7, mainly since Collins used them, but was 
steered away from it because it's supposed to be noiser than 6BE6's.  That's 
why they're several mixer mods out there for 75A4's.  Pentagrid mixers are 
noisy no matter which one, one uses.

One thing when design work is done is to look at the environment you're in.  
I live a rather noisy (electrically) area.  An RF stage doesn't do a thing 
for me except amplifie the noise along with everything else.  Now the place I 
have in PA is quiet.  Overhead AC lines are the only thing I have to be 
concerned about.  Heck, if I tune around 21 Mhz, I can tell if the farmer 
down the road is plowing his field by listening for his tractor's ignition 
noise, and he's 7 miles away.  Now that's a quiet area!  An  RF stage might 
be useful in this case.

I guess the point I'm trying to make is that for one's own design you can go 
anyway you want and one of the errors people make is to duplicate an existing 
circuit because everyone doing it or if it was good enough for Collins it 
must be great.  Not so.  Having been a designer (I did computer interfaces) I 
had a ton of great of ideas and designs that didn't work.  Mainly since they 
were economically unfit or very user unfriendly, usually the former, but not 
because they didn't perform well.

In fact the HBR series design philosophy was to put out there a receiver that 
was fairly easy to build, and relatively half the price of a simliar 
commercial job.  It works well for a 50's design, but even Crosby never said 
it was a world beater.  Just very good.  I'd love to duplicate the HBR-16 but 
I don't have the wherewithal to dig up some major parts, like the variable 
cap, and 100 Kc transformers.  So for now it's up to my own devices.

So much so for now.  Once I get started...bla,bla, bla

Regards,
Helm.  WB2ADT