Topband: Add 160 to SB-200 ?

[Lars Harlin]

----- Original Message ----- 
From: "Mike Waters W0BTU" <mrscience65704 at yahoo.com>
To: <topband at contesting.com>
Sent: Sunday, March 15, 2009 7:42 PM
Subject: Topband: Add 160 to SB-200 ?


>
>
> Hello,
>
> I'm looking for a proven design to add 160 meters to a Heath SB-200 
> without disabling 80-10.

Hi Mike!

I did that mod to a Yaesu FL2100, wich is very similar to SB200, many years 
ago. The trick is to add some inductance to the tank and also add 
capacitance for C2. Then you must be able to take the added values out of 
the circuit for all bands but 160. The inductance should be added at the lo 
Z end of the tank. I used a iron powdered toroid core, TO-225, with 16 turns 
of teflon insulated wire, 1000 pF fixed ceramic cap wich must be able to 
handle high RF current (block type) and a SPDT relay, preferably vacuum. The 
relay is wired so that it normaly shorts the toroid in series with the tank. 
When you activate the relay, the short opens and put the toroid in the 
circuit and the other pole of the relay connects the added 1000 pF to C2 
(the lo Z end i.e. antenna output). I can mail a drawing directly to you, if 
needed.

73's es GL!

Lars/SM3BDZ