[minima] Re: Anything special about T3's capacitor to ground?
- From: Mvs Sarma <mvssarma@xxxxxxxxx>
- To: minima@xxxxxxxxxxxxx
- Date: Wed, 26 Feb 2014 17:49:50 +0530
Thomas,
please see whether the core qualifies for the AL value specified for
FT37-43. Wind 10Turns and measure inductance. it would be AL /10. as per
www.kitsandparts.com datasheet is 350 with 20% Tol
On Wed, Feb 26, 2014 at 1:29 PM, Thomas Sarlandie <thomas@xxxxxxxxxxxxx>wrote:
> Mark,
>
> If you have a chance, I would be very interested in reading what is the
> signal strength you measure here at the output of that transformer. I might
> be looking at a problem that does not exist - maybe my sensitivity problem
> is somewhere else.
>
> Mvs Sarma: Thanks for the tips. I have tried smaller capacitance without
> any success and I have looked hard for solder bridge. I might try building
> a new mixer out of circuit to make sure I start from scratch.
>
> 73,
> thomas
>
>
> On Mon, Feb 24, 2014 at 9:25 AM, Thomas Sarlandie <thomas@xxxxxxxxxxxxx>wrote:
>
>> Mark,
>>
>> I am getting confused too ;)
>>
>> The radio is in RX. I believe my audio amp works ( I can receive AM
>> broadcast by putting my finger on the input wire ). I can also receive my
>> 3kHz tone even with my capacitor in the circuit. My problem is I don't
>> receive any other signals. It's like the receiver is completely deaf except
>> to very strong signals applied to the input.
>>
>> When you say it's normal for the input of the audio amp to be weak, how
>> weak are we talking? Micro-volts? Milli-volts? Should I be able to see
>> something on the oscilloscope? Maybe the very high impedance output is
>> normal.
>>
>> If it is, then my sensitivity problem might be somewhere else. How could
>> I test that?
>>
>> Can you confirm that plugging an antenna on the receiver makes a
>> difference in the level of noise you can listen to? Plugging an antenna on
>> mine makes absolutely no difference to the noise strength.
>>
>> thanks again for your replies!
>> thomas
>>
>>
>> On Mon, Feb 24, 2014 at 1:41 AM, Mark G0MGX <mark.g0mgx@xxxxxxxxx> wrote:
>>
>>> Hi Thomas
>>>
>>> I think I am getting confused (nothing new there). If the radio is in TX
>>> then the point where your scope is connected is where we would inject audio
>>> to mix with and modulate the BFO signal. If we are in RX (that's my
>>> assumption) then we would only expect to see the injected signal being
>>> modulated i.e. an audio signal and very weak one too - most of the gain in
>>> the Minima is at audio. Is the audio amp working (does it buzz when you
>>> stick your finger on the input)? I am not sure what you should expect to
>>> see at that point? The audio tone there will also alter and be totally
>>> dependent on the tuning of the LO and hence the output of the mix.
>>>
>>> If your scribbles are correct then the transformer looks correct to me.
>>> Without checking the signals on mine I can't help much more until I get
>>> home (Thursday)....
>>>
>>> Mark (just boarding in Abu Dhabi & bound for London)
>>>
>>>
>>> On 24 February 2014 08:48, Mvs Sarma <mvssarma@xxxxxxxxx> wrote:
>>>
>>>> thomas,
>>>> even a cheaperTA7358 and perhaps LKA1168 or so ( a compatible) would
>>>> also work, I suppose
>>>>
>>>>
>>>> On Mon, Feb 24, 2014 at 1:29 PM, Thomas Sarlandie <thomas@xxxxxxxxxxxxx
>>>> > wrote:
>>>>
>>>>> Raj: Yes I have all the dots on the same side. I have checked several
>>>>> times now. Unless I am really reading something backwards I think I have
>>>>> that covered.
>>>>>
>>>>> Farhan: I don't but I will look into that. Would a ne602 work too?
>>>>>
>>>>> It's really raging to see my 4KhZ signal get out of the mixer but not
>>>>> be able to tame it into the audio pre-amp because the output impedance is
>>>>> so high. What could explain this? I will take any theory ;)
>>>>>
>>>>> 73,
>>>>> thomas
>>>>>
>>>>>
>>>>> On Sun, Feb 23, 2014 at 11:07 PM, <farhanbox@xxxxxxxxx> wrote:
>>>>>
>>>>>> Thomas, if you have an ade-1, just drop it into the circuit.
>>>>>> - f
>>>>>> Sent from BlackBerry® on Airtel
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Raj <vu2zap@xxxxxxxxx>
>>>>>> Sender: minima-bounce@xxxxxxxxxxxxx
>>>>>> Date: Mon, 24 Feb 2014 12:29:53
>>>>>> To: <minima@xxxxxxxxxxxxx>
>>>>>> Reply-To: minima@xxxxxxxxxxxxx
>>>>>> Subject: [minima] Re: Anything special about T3's capacitor to
>>>>>> ground?
>>>>>>
>>>>>> Thomas, please check all three DOTS are from the same end of the
>>>>>> transformer.
>>>>>> Most important that same winding start and end is correct.
>>>>>>
>>>>>> At 24-02-2014, you wrote:
>>>>>> >Thanks Mark. That's how I have been doing it. I was not sure because
>>>>>> T1 & T2 do not have those dots. Is it because phasing is not important on
>>>>>> them?
>>>>>> >
>>>>>> >I have just rewound a new T3 using a new roll of #32 AWG wire on a
>>>>>> new FT37-43. I get the exact same problem. So here is a picture of what I
>>>>>> am doing with some labels as to where the wires go. I hope I am doing
>>>>>> something very stupid and someone will be able to point it out:
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Regards
>>>> Sarma
>>>>
>>>>
>>>
>>>
>>
>
--
Regards
Sarma
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