[600MRG] RBA's and RAK's

[NMF]

One thing I tried on a pristine RAK one owner was to just disconnect the 
power supply and put it aside...

Next was to solder MPF102s to each tube socket base along with 
appropriate R and C coupling, add 9V battery and it will run for at 
least 2 weeks if left on...
Keep the tube in in order to not have to 'retune' the selective TRF 
filters...

Adding 2 BNC connectors also made for double use as the TRF stages as an 
amplified 'pre-selector', man that rig is tight, very high quality!!!




On 11/3/2014 12:32 AM, Bill Cromwell wrote:
> 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
>>
>>
>> _______________________________________________
>> 600MRG mailing list
>> 600MRG at w7ekb.com
>> http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>>
>
>
> _______________________________________________
> 600MRG mailing list
> 600MRG at w7ekb.com
> http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>