[ARC5] Frequency shift with percussion

[Kenneth G. Gordon]

On 2 Mar 2015 at 8:41, Scott Robinson wrote:

> Folks,
> 
> I have part of an RF noise meter, essentially the front end and IF strip 
> of a nice multi-band radio, built in large part with subminiature tubes. 
> It needs a detector, power supply, and audio amp.

Interesting: what model of noise meter? The reason I ask, is that I have a 
bunch of Stoddart Noise Meters here...

> I have it restored and working, but as the upper bands use a 1600 KHz 
> IF, it could use better selectivity. I've thought about a non-crystal 
> controlled down converter to 455 so I can buy a 7 KHz BW (no SSB use 
> contemplated) crystal filter and sharpen up both IF frequencies with the 
> same filter. I expect I can make a stable enough 2055 KHz conversion 
> oscillator without fussing with crystals, so long as I keep the 
> oscillator coil away from local heat sources or temperature compensate it.

Shouldn't be a big problem: however, I really do like crystal-controlled 
oscillators for that type of service.
 
> The detector will of course have a separate AVC rectifier so it can get 
> down to 90+% negative modulation, and will have fast attack/slow decay 
> timing. The audio will be to my specs, probably using a 6BX7 PP dual 
> triode, good for about 4W,

The 6BL7 is another good one...

>  1-3% distortion and a low output impedance 
> for better speaker resonance damping before feedback. I modified my 
> Hammarlund SP600 (audio only) with this circuit to good effect, no new 
> holes anyplace visible either.

I am curious to see a good schematic of this circuit...

> The basic piece will remain largely as it was, except for replacement of 
> unobtanium interface connectors.
> 
> Keeps the old man off the streets and outa the bars, it does.

Indeed. My sweet wife always knows where and when to find me when she 
needs me.

I can enjoy a wee dram of single-malt with her at home for far less cost than 
trying that at a bar, and the company is so much nicer. ;-)

Ken W7EKB