Question about 4S Tuner


Timothy East
 

I built the tuner and cannot seem to get any response out of it.
I never experience the response shown on various videos.
There doesn’t seem to be any position on central knob with louder audio.
Examination of the build does not reveal any obvious issues. Does anyone have any suggestions?
It’s too bad really as the build turned out with a handsome unit I’d like to use with my BJ.

Tim
K0EMP


Curt
 

Tim

Very unusual for a tuner not to work at all, unless wire is way to short. Check that connections are real with a dvm, once myself I experienced a connector solder joint that wasn't real but open.

Try on different bands, like 80m which has more noise.

Curt


Jim, N5IB
 

Hi Tim,

Since you're not hearing any peak in background noise or signal when making adjustments, it's probably something in the LC Tee network, rather than in the SWR bridge or indicator circuit.

First question... is there any change in background noise when you switch from "IN" to "OUT" ?

Second... measuring from the top of L1 to ground with an ohm meter, is there essentially a DC short (~ zero ohms) for ***every*** position of SW1 ?

Third... measuring from J1-1 to J2-1 with the SWR bridge "OUT" do you see an open circuit condition ? With the bridge "IN" do you see a few ohms ?

Fourth... do you have any instrument capable of measuring capacitance in the tens to hundred of pF range ? If so, can you check C1 and C2 that they do in fact vary from a couple of tens of pF up to their max of 250 pF

Jim, N5IB


John Lonigro
 

Tim:
The tuner has two distinct parts.  If you are using it with a receiver, the only functional parts are the two switches (SW1 and SW2), the two variable capacitors (C1 and C2), and the inductor (L1).  Without a transmitter, the other part won't work.  For one thing, that part gets its power from the transmitter's RF - no RF, no power.

So all you have to check are the components I mentioned, as well as the connectors J2 (input from radio) and J1 or ( J3 and J4).

The first thing I'd do is toggle the IN/OUT switch to OUT and keep it there.  The "IN" position only works with a transmitter attached to J2.  That may have been your problem.  Tune in a station, then rotate C1, C2, and L1 to see if there's any change in signal strength.  Don't look at the LEDs.  They won't light.  If you get no change, you need to check your wiring on those components.

Good luck and 72,
John, AA0VE

On 1/9/21 7:55 AM, Timothy East wrote:
I built the tuner and cannot seem to get any response out of it.
I never experience the response shown on various videos.
There doesn’t seem to be any position on central knob with louder audio.
Examination of the build does not reveal any obvious issues. Does anyone have any suggestions?
It’s too bad really as the build turned out with a handsome unit I’d like to use with my BJ.

Tim
K0EMP




Timothy East
 

Ok. Thanks

On Jan 9, 2021, at 8:26 AM, Curt via groups.io <wb8yyy@...> wrote:

Tim

Very unusual for a tuner not to work at all, unless wire is way to short. Check that connections are real with a dvm, once myself I experienced a connector solder joint that wasn't real but open.

Try on different bands, like 80m which has more noise.

Curt


Timothy East
 

Thanks, I’ll check on this.

On Jan 9, 2021, at 8:33 AM, Jim, N5IB <n5ib@juno.com> wrote:

Hi Tim,

Since you're not hearing any peak in background noise or signal when making adjustments, it's probably something in the LC Tee network, rather than in the SWR bridge or indicator circuit.

First question... is there any change in background noise when you switch from "IN" to "OUT" ?

Second... measuring from the top of L1 to ground with an ohm meter, is there essentially a DC short (~ zero ohms) for ***every*** position of SW1 ?

Third... measuring from J1-1 to J2-1 with the SWR bridge "OUT" do you see an open circuit condition ? With the bridge "IN" do you see a few ohms ?

Fourth... do you have any instrument capable of measuring capacitance in the tens to hundred of pF range ? If so, can you check C1 and C2 that they do in fact vary from a couple of tens of pF up to their max of 250 pF

Jim, N5IB