[Elecraft] K2 vs. Drake 2B - New vs. classic.

[Mike Harris]

G'day,

|I don't think that the speaker that is the problem. I can hear the 
raspiness
| on the internal speaker and several external speakers. Haven't tried
| headphones, don't like them and don't have any.
|
| The raspiness I am hearing is similar to placing an AC transformer and 
the K2
| too close together. My K2 is at least two feet from any AC transformer 
and
| run from an 18 Ah gelcel battery charged by a one amp A&A Engineering 
Smart
| Charger. I do notice that the charger can increase the raspiness at 
times.
| Switching it off reduces the raspiness. The chargers are connected to 
the AC
| mains via a Tripp-Lite Isobar Ultra surge and EMI suppressor.

This has triggered a thought.  I run my K2/100 from a Samlex SEC 1223 with 
no activated transformers anywhere near it.  My Pro.Sis.Tel rotator 
controller is usually turned off and I do have the VCO shield mod 
installed in anticipation of some big iron (Acom 1000).  When I first put 
the SEC into service I connected an HF-225 receiver to it and there was a 
nasty noise on the af.  The HF-225 doesn't have anything filtering on the 
12V before it hits the af amp.  On the wall wart it is fine.  It seems the 
only thing between the K2 af amp and the 12V is some decoupling by R16 (10 
ohms) and C28 (220 microfarad).

Maybe the SEC is pumping noise into the af amp.  Sadly I don't have a 
linear PSU or suitable battery to hand at present.  I have been planning 
to shift to a linear PSU 'cos the SEC kicks up a din on the LF bands every 
25kHz or so.  There is a mod to the SEC to improve the noisy output 
situation, must get the ferrite beads and do that.

Regards,

Mike VP8NO