[Kenwood] TS-520S questions

[Bryan Swadener]

Lloyd,

See page 10 in the SM-220 manual.  It says you'll be adding a 22pF capacitor, 10K resistor, and 12" piece of RG-174/U 75 ohm (sic) cable. 
Think of it as a capacitive voltage divider (the 10K resistor doesn't do much).  You have a capacitor in series (22pF) to the mixer output, and a capacitor to ground (the capacitance of the RG-174/U, about 30pF/foot).  This makes for around 4.5dB attenuation right off the bat.  The cable between the rig and Panadapter adds to the shunt capacitance. The less capacitance to ground, the more signal at the input of the SM-220.  Between the TS520 and SM220, use only enough RG-174/U (or RG-58/U) as you need.

I have owned an SM-220 (w/ BS-8) for many years.  Yours needs to have the BS-5 unit.  I initially used mine with my olde TS-120 & TS-130 rigs.  To make the capacitance of the RG-174/U a non-issue, I built a dead-bug buffer amplifier inside the rigs (http://www.geocities.com/bswadener/panadapter/).  Your TS520 uses a 3.395 MHz IF, while my TS120 & TS130 rigs have a 8.830 MHz IF.  Different frequencies but same principle.  For various reasons, I never liked the SM-220 as a Panadapter.  I'm using the Heath SB-620 "Scanalyzer" instead.

73,
Bryan WA7PRC

> I am in the process of installing the IF #1 output on my
> 520s. I have an 
> abundant supply of RG174.
> Is this OK and how long should I make the coax between
> radio and SM220?
> Any other pitfalls?
> 
> Thanx
> Lloyd Godsey