[Premium-Rx] WJ-340A manual

[John Reed]

>
> I don't  think you'll find much similarity between the 340A and 357 WJ
> receivers.  The 357 is tuned with an air variable capacitor and the  340A
> with a voltage variable capacitor diode. As far as the stability of  the 
> 340A
> I found it poor compared to the  357.
>
> Thanks for the correction....and whoops:-)
>
> Whilst I was offering the suggestion of similarity more in terms of
> operating priciple rather than actual circuit detail, and thinking the 
> 357 manual
> might be better than nothing, I did assume the 340A  would also have 
> physical
> capacitive tuning.
>
> I must admit though that I based that on the external physical 
> similarities
> between the 340A and the DMS105, with which I'm more familiar, so perhaps 
> not
> the most scientific of deductions.

They aren't electrically very close either.  The 340A is double conversion, 
and the 357 is single conversion with an IF of 2 MHz.  I don't know the IF 
frequencies of the 340A.  The DMS105 is also single conversion with 2 MHz IF 
so it is close to the 357.

I modified my 357 with crystals for the BFO for CW, LSB and USB positions. 
I also disabled the tuning lock stabilizer.  I found it's stable enough 
without it, and it just added instability when not being used.  The analog 
tuned BFO is not stable at all.  It drifts all over the place.

It's a good LF receiver, but I use the Harris RF-590 for most of my LF dxing 
now.  The 1 Hz tuning is hard to beat.

John Reed

John Reed