[600MRG] RBA's and RAK's

[Bill Cromwell]

Hi Rudy,

I have one of those RAKs, too. I didn't know that I can't feed WSPR with 
an audio spectrum shifted down to fit through the filters. I am not 
going to defeat the filters in the RAK. I'll go to the BC453 after I get 
the power supply rebuilt. This time I'll feed regulated DC to the 
heaters AND the B+. I know for sure the BC453 was shifting the frequency 
when the power line load changed. I could watch traces on the waterfall 
display making small, slow waves as it wandered around and sometimes 
jumped when my beer cooler fridge or the furnace blower motor kicked on. 
The regulated supplies will take care of that.

I have not been fussy enough setting up the radios in the belief that 
putting the WSPR signals in the middle of the rx passband and adjusting 
the radio dial to put that spectrum into the WSPR machine would work. I 
assumed that getting the WSPR signal into the sound card anywhere in 
it's operating range would allow it to decode even if it reported the 
wrong frequency. Eventually I'll get around to trying it on my BC453 or 
the Kenwood in SSB mode after I get a converter working. The RAK is 
clearly not going to make it on WSPR even though the power line voltage 
excursions do not move the traces on the waterfall. It already regulates 
the B+. I understand the RAL does not have the audio low pass filter 
that is always inline with the RAK. The front panel filter selections 
may be turned off on both radios. RAL goes down to around 200 or 300 kc 
if I recall correctly (I don't have one).

73,

Bill  KU8H


On 11/02/2014 10:45 PM, Rudy Severns wrote:
> I have both RAK and RBA receivers and there is  a reason why WSPR 
> reception may be a problem.  With WSPR the audio output to the sound 
> card is in the range of 1400 to 1600 Hz.  Both the RBA and the RAK 
> have very good audio filters designed to suppress audio tones above 
> 1200-1300 Hz.  In the RAK there is a audio tuning switch which lets 
> you tune the filter from 450 to 1300 Hz but the filter attenuation 
> drops quickly so you may have some problem with WSPR.  I'm taking this 
> information from the manual, I haven't had a chance to actually 
> measure the filter responses but I know in the RBA the filter is 
> pretty sharp even in the "broad" position.  My problem with the RBA is 
> that the filter, when in the narrow band position, is centered at 1 
> kHz.  This is a problem with my hearing which is much better somewhat 
> lower in frequency.  I'm looking at modifying the filter to suit my 
> needs for CW but I don't know if I'll fix the WSPR problem.  I haven't 
> had a chance to look closely at the actual response.
>
> Why you might have a problem with a BC-453 I have no clue.  I don't 
> think they have the narrow audio filters.
>
> 73, Rudy
>
>
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