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Discussion Starter · #21 ·
KT-700 Bench
Note: The two switch DIP switch operates as follows: SW1 - Down - Separate inputs, SW1 - Up - Combined on UHF Inputs, SW2 appears appears to have no function.
Okay, here's the way the switches work.

SW2 does have a function.

SW1 and SW2 should always be opposite.

SW1 ON and SW2 OFF is combined input.

SW1 OFF and SW2 ON is separate inputs
 

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Okay, here's the way the switches work.

SW2 does have a function.
You must have got instructions with yours. I didn't get any. With SW1 OFF, SW2 barely does anything. SW2 ON increased the VHF gain by 0.15 to 0.5 dB across the band. I drew out the input circuit. SW1 switches Combined in and out. SW2 switches two capacitors in/out to ground. The VHF input is never actually disconnected. The gain through the VHF port when the switches are set to Combined decreases the VHF gain by 2 dB at the low end, gradually decreasing by 5 dB at the high end. See image. All 3 traces are taken with the input signal connected to the VHF input.

It's important to get the switches set correctly to maximize VHF performance since the VHF input is not fully disconnected.

3023825
 

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Discussion Starter · #23 · (Edited)
Calaveras,
Thank you for the follow-up graphs. Your reviews are impressive.

I got that switch information from Kitz.

Because they are so new, thats probably why we didn't get instructions. I know he rushed them out. Regardless, I asked for mine to be set up for both UHF and VHF inputs. I never messed with mine.

I got an email from Kitz. He was adamant about no matter where they're set the switches need to be opposite. So the instructions I got from Kitz early on were in the email... I barely read them. Simply because my KT 700 was ready to go.

I've been meaning to reach out to you. I thought I did but then the AVS Forum was down and the private message disappeared. I spent 15 minutes typing a detailed private message only to see it evaporate when I hit send.
 

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You must have got instructions with yours. I didn't get any. With SW1 OFF, SW2 barely does anything. SW2 ON increased the VHF gain by 0.15 to 0.5 dB across the band. I drew out the input circuit. SW1 switches Combined in and out. SW2 switches two capacitors in/out to ground. The VHF input is never actually disconnected. The gain through the VHF port when the switches are set to Combined decreases the VHF gain by 2 dB at the low end, gradually decreasing by 5 dB at the high end. See image. All 3 traces are taken with the input signal connected to the VHF input.

It's important to get the switches set correctly to maximize VHF performance since the VHF input is not fully disconnected.

View attachment 3023825
sw1=on and sw2=off is combined input.
sw1=off and sw2=on is separate inputs
sw1 and sw2 should always be opposite
 

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I'm likely in for one of these - a very very stupid question, though...

With these double-input preamps, if only the combined input is used, should the VHF-only be terminated?
 

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Discussion Starter · #29 ·
Thanks. Doesn't shock me Kitz goes to that length to describe.
Well here's his actual description:

"If using the combined input and the switches are set to combined, you do not terminate the VHF port. If you have the switches set to separate inputs and you are only using one input, the other should be terminated."
 
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