[ARC5] Quick sensistivity comparison

[Richard Knoppow]

----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "Glen Zook" <gzook at yahoo.com>
Cc: "ARC5" <arc5 at mailman.qth.net>
Sent: Thursday, June 13, 2013 10:42 AM
Subject: Re: [ARC5] Quick sensistivity comparison


On 13 Jun 2013 at 10:04, Glen Zook wrote:

> Actually, tube-type ("valve") receivers routinely give 
> better LDS /
> MDS (least descernable signal / minimum descernable 
> signal) signals
> than solid-state equipment. Things like phase noise are 
> definitely
> higher in "modern" solid-state equipment. Now, generally 
> for
> operation on MF and HF, the ambient noise levels on the 
> bands negate a
> lot of the LDS / MDS. That is, the noise level is often 
> substantially
> above the weakest signal that the receiver is capable of 
> receiving.
> As such, the improved sensitivity is not needed when an 
> antenna is
> connected to the receiver.
>
> I routinely get LDS / MDS level of well under 0.1 
> microvolt (and the
> leakage from the generator is extremely low) on receivers 
> like the
> Collins S-Line, Heath SB-Line, Drake 4-Line, etc. Even on 
> general
> coverage receivers like the HQ-140X, SX-100, etc., the LDS 
> / MDS is
> often below 0.1 microvolt. Glen, K9STH

Thank you, Glenn. :-)

Ken W7EKB

     Before definitely settling on the new tube check the 
overload point with both. perhaps it won't make much 
difference but if the front end overloads easily it may be 
worse than some noise.
     On my RCA AR-88 which uses 6SG7 tubes in the RF I get 
similar results to what Glenn reports above. Level for 10db 
Snr is around 0.8 uv using the 3 khz bandwidth and about 1.2 
uv for the 8khz bandwidth. Minimum discernible level with 
BFO is the leakage from my -hp- 606-A. This is at any 
frequency up to 30 Mhz.  The overload limit on the AVC is 
somewhere around 80K uV to 100K uV depending on frequency 
and nearly a volt with the RF manual gain at minimum.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com