[Milsurplus] RAL design defect

[Kenneth G. Gordon]

On 25 Sep 2006 at 12:43, W7QHO at aol.com wrote:

> In a message dated 9/25/06 9:17:46 AM, rbrunner at gis.net writes:
> 
> 
> > I've been enjoying my RAL, hearing everything, but thought it
> > excessively noisy.  When the detector goes into regeneration it
> > sounds like a mighty waterfall when it should be barely noticable. 

Hmmmm....mine never sounded like that. Very quiet, in fact. Boy! You 
sure have had some weird problems with your RAL.

> Hmmm...   In my RAL hear a definite "rushing" sound at the
> regeneration point which becomes a "plop" if one crosses the threshold
> quickly.   No "mighty waterfall" effect though.

Same thing for me. The receiver is very quiet, and has plenty of gain. 
The only way I can hear the "plop" is if I swing the regen control very 
fast through that point. Otherwise, it goes into and out of regeneration 
so quietly it is sometime difficult to tell.

> Have found my set to be somewhat short on audio gain.   Maybe I need
> to check into that.

Yes, I agree. Maybe your limiter stage is acting up.

I used an RAL-7 as my main station receiver for many years, and have 
another one now. I use headphones exclusively with it. It has plenty of 
audio gain for me. In fact, the audio stage runs wide open all the time. 
The "gain" control is actually an RF gain control. I always felt that my 
RAL-7s needed an audio gain control. It is actually pretty easy to add, 
but the control ends up in a weird place: high and to the right of the dial 
window.
 
> What are others hearing?

1) No waterfall sound at all. Very quiet and sensitive receiver

2) Plenty of audio gain when used with headphones (for which they 
were designed).

3) Regeneration is so quiet it is sometimes difficult to tell whether it is in 
that condition or not. Thus the front-panel push-button switch.

4) Sensitivity compares very favorably with modern receivers. 

In fact, my RAL-7 hears everything my restored HW-101 does, and the 
HW-101's measured sensitivity is around 0.1 microvolt for MDS 
according to my HP-8640B. 

However, I don't really believe that the 0.1 microvolt figure is accurate, 
since I KNOW I have leakage somewhere. 

Still, I hear band-noise up through 23 Mhz with the RAL-7 whenever I 
connect any wire to the antenna connector, even one only about 6 feet 
long.

And the way I figure it is if the identical setup is used with whatever 
receiver I test, at least the COMPARISON is more likely to be valid.

YMMV.

Ken Gordon W7EKB / WC2XSR