[NLRS] 10368 transverter

[Dr. Gerald N. Johnson]

On Sat, 2006-02-18 at 10:37 -0600, Doug Reed wrote:
> 
<SNIP>
> If you put an RF attenuator after your IF radio you can do the same 
> thing using it as the signal source in CW mode. Just watch the power 
> dissipation of the attenuator. You should probably put a 6dB or 10dB pad 
> ahead of the variable attenuator, just to be safe. If you don't have a 
> good fixed pad, try 100-200 feet of cheap RG-58 coax.....

Better if its expensive RG-58, then it won't leak as much through the
braid, it will still have plenty of transmission loss. RG-174 has a lot
more loss per hundred at 2m and is more compact.
> 
> If you don't have a good variable attenuator to use, you can get some of 
> the benefit of variable signal level by connecting a 1 KHz sinewave 
> audio signal generator into the mike input while in SSB mode and running 
> that signal up and down. But don't expect more than 30-40dB of signal 
> level difference because there is some amount of carrier and sideband 
> leakage.
> 
> I suggest using a 200:1 resistor attenuator at the mike input so the 
> audio generator can run in its normal 0-10 volt range. Use 100 ohms 
> across the mike input and 10K to 50K in series to the generator. This 
> will help eliminate hum and noise from the audio leads but will NOT 
> eliminate ground loops.

Only 200:1? 10 volts down to a millivolt takes 10,000:1... Only carbon
mike inputs needed a volt, dynamic/electret microphones run below a
millivolt output.

> 
> Combining the audio generator and fixed or variable RF attenuators would 
> allow you to cover a fairly wide range of signal levels, within the 
> limits Jerry mentioned.
> 
> I expect that one of these ideas is what DEM had in mind.
> 
> 73, Doug Reed, N0NAS.

-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer