[HBR] Re: HBR2K Explanatory Footnote

[hbr@mailman.qth.net]

Hi Helmut:

No, I'm sorry, I don't, at least not in convenient on-line form.   I follow 
the diagram given in an old Electric Radio article and I could mail you 
a copy of that.   But let's see if I can talk you through drawing it.

6ES8 dual triode.   

Cathodes connected together and through 560 ohm to ground.

Grid of left unit pin 7 to ground thru 100k.   Inject signal input here in 
the usual way.

Grid of right unit pin 2 to *cathode* through 100k.   Inject local osc. 
voltage here in usual way.

Plate of left unit pin 6 through .01 cap to ground.   Also connect to 
voltage divider below between 3.3k&10k.

Plate of right unit pin 1 to output transformer primary, typically an 
IFT.   Other end of transformer primary to voltage divider between 
10k&47k which should be bypassed.  

Voltage divider -- from B+ through 3.3k 1w to 10k 2w to 47k 1/2w to 
ground.

I think this assumed a supply voltage of about 175 volts.  Divider 
resistors should be adjusted to get about 151 volts on plate of left 
unit, 58 volts on right unit; these voltages are said to give the best 
IMD performance.  It does work very well, though I haven't done 
proper performance testing.

The values are due to Ray Osterwald -- he was the author of the 
article.  

> Would you happen to have a schematic of the Pullen mixer you speak of?
> 
> Thanks,
> Helm.  WB2ADT
> 
> 
> 
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