[Elecraft] Re: VOX sensitivity

[Julian, G4ILO]

I presume you're referring to his mod C: the addition of a 4.7K resistor to 
"prime" the compressor? No, I haven't tried that, but it looks simple 
enough to do so I might try it. I didn't realise that the VOX sensitivity 
was affected by the compression level. I use SSBC 3-1 already, and unlike 
G3RXQ I don't wish to use any higher setting. I can make VOX work with my 
desk mic by increasing the gain of its built-in preamp, but it doesn't help 
to have one mic with a much higher output than the others due to the lack 
of an effective mic gain control on the K2. In fact, I only want to use VOX 
with a head-set, which has no built-in preamp, and won't trigger the VOX at 
SSBC 3-1 even if I shout.

I think the lack of both gain and adequate control over the input audio 
level *before* compression is one of my few niggles about the K2. The 
number of people who have resorted to building preamps suggests that 
something ought to be done about it. I would have built a preamp myself if 
I was capable of doing it on a small board that could be fitted internally, 
as G3RXQ did. If someone came up with a small kit for this there might be a 
market for it. Even a schematic and a perf board layout would be a help for 
those of us who don't have the expertise to come up with our own circuits. 
Although there are plenty of preamp circuits around, designing one to fit 
into the K2 is a lot more tricky.

73,
--
Julian, G4ILO. (RSGB, ARRL, G-QRP)
G4ILO's Shack: http://www.qsl.net/g4ilo





  ==== Original message ====

> Julian,
> 
> Have you considered the addition of a small compression to the 1:1
> setting to increase VOX sensitivity, see
> http://www.ac6rm.net/mailarchive/html/elecraft-list/2003-06/msg01036.htm
> l and
> http://www.ac6rm.net/mailarchive/html/elecraft-list/2003-08/msg00162.htm
> l (G3RXQ)? 
> 
> --
> 73, 
> Sverre
> 
> ------------------
> Sverre Holm, LA3ZA
> www.qsl.net/la3za