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he can turn down "drive" to get lower output

turning down bias makes distorcion (clas c and not class a or class ab)

so drive lower ... yes ... bias lower ... no

in fact a higher bias gives cleaner signals (with a bit more heat)

greetz sigi dg9bfc

Thanks John for your answer

PB:? ?i don't found any reference for a 433,9 mhz transformer !

some ideas

cdt

John - Couldn't you just turn down the PA BIAS until you get the output you need?

73,

Justin
KI5GKD

Ordering a uBitx v6 Thursday to use as a transverter rig for a transverter that needs between 1 mW to 750 mW input on 10m.? Anybody have any suggestions on how to mod the uBitx to limit output to around 500 mW?

73 de W5NNH

Mini circuits, or if you want to do filter use one of the cheap Murata or similar ceramic filters.

开云体育

what about using an arduino and control a si chip as a tuneale clock like we du in bitx

depending what clock you use (and if you add a clock divider to a faster unit) you can do wide or narrow sweeps

... or just buy one of the simple analyzers that are build that way (like tiny SA)

greetz sigi dg9bfc

Hello,

Do you know where to find a 433.9 mhz transformer like TOKO case in Europe? or how to do one?
It’s possibly for this montage. Nothing decided.



You may say it’s an old montage, but it may be enough for what I do.
It can be ameriored with SMD components.
The disadvantage of this small analyzer is that the scan is always between 1 and 300 MHZ. In fact the starting point of the féquence will always be to the left of the screen.?The action Span, only "enlarges" the sweep width and will give only 1 to 15 MHZ for example.
I don’t know if we can change or add some?components to be able to center the base frequency in the middle of the screen.
Advantage of this small assembly, there is a possible tracking to make and associate. (ex testing filters)
Of course if you have better and easy to do (no need of Gigahertz) with description and schématics + typons, I am interested.
cdt

John, I'm part of a brave group building homebrew simple transceiver.? If you have one or two left, I and the group would put them to good use?

Hi Evan,

OK all clear now.
Unfortunately even in FAST position (the position I normally use), it looks quite slow, but that's not such a big issue.

Thanks?
Giuseppe
IZ4JUK

Hi Giuseppe,

You should see a change from the Fast to the Slow setting of the AGC corresponding to the speed of the S Meter update.? The value you are measuring in the S Meter function is the bias that is being sent to the two FETs that reduce the RF signal to the rig.? I do not know of a way to speed up the readings other than to maybe go back to the LM358 sensor and play some more with the capacitor value.

The other limiting factor is the speed of the Nano to read the value.? This may be the real delay in the update time.? The evidence to support this is the criticality of the capacitor selection.? The Nano is being pushed pretty hard in the ?BITX in all aspects of the capabilities of the device.? One of these days I may attempt to port the code to the Teensy 4.1 and use the Raduino that is supplied by Triumvirate Skonk Worx:


I have purchased the Raduino from them, I have the Nextion, just need to start working on the code.? That is not a small task (or else someone else would have done it already;-).

Hi John,
I like the idea of the variable resistor in place of the switch.? I will need to try it on one of my ?BiTX.

73
Evan
AC9TU

Sounds like Gary is affirming 1206 sized resistors.?

Many of us found that c81 needs to be experimentally determined, as its part of an equalization network. Mine without Allison's redesign needed adjustment. If you have an assortment of c0G, no or similar leaded caps they will work here. Whether to use small or leaded with manual assembly at HF is mostly about appearance.?

Curt

/g/BITX20/message/48729

Hi John,
I'm afraid your are speaking about the AGC fast-slow reaction, instead of my question regardin the SMeter reaction, which is quite slow.
Am I right?
Giuseppe

I have replaced the fast / slow positions with a 5Mohm potentiometer that is connected to the off points. Now I can adjust it from off to nice and slow? I use a linear taper for now but am looking for a log taper to see how that changes the characteristics of the adjustment . I like that solution a lot better than the previous 2 position switch.

John

Hi Evan,
well, thank you very much, as this was the problem! Now the SMeter works!
I just had to set up the right values and now the reading works. So many thanks for you help!
It's not very fast, quite similar to the previous circuit (),?therefore not big imprevements apart the leaner setup inside the uBitx.
Any chanche to make the SMeter faster in the reading?
The delay between what we receive and what we see on the smeter doen's create big problems, but a matching between between them would be nice.
Have a good Sunday
'73
Giuseppe IZ4JUK

Hi Giuseppe,

From what you are describing, I believe that there is a calibration issue with the CEC software.? I would recommend you follow the method using the S.Meter Assistant button, reading the high and low values as described, then select the response curve to set the meter points.? It should be described on the web page that I sent you.

I had a similar problem calibrating the S Meter until I found the assistant and the automatic scaling function in the Memory Manager software.

73
Evan
AC9TU

Hi Evans,

I checked in the uBitx options under the View ADC menu, and putting the frequency on a signal, I read values increasing depending on teh station signal, until 250.
Therefore apparently the A7 pin gets the value from tha raduino.

Shold I probably try to drastically increase the values on the Memory Manager? As the values advised by KD8CEC do not show anything to my smeter.

COncrning the memoru manager version, I was using the 1.97. I now downloaded the last 1.11, thanks for it.

Regarding the AGC ON, yes I read it. I'd say that it'll always be ON, in slow of fast position. I won't put AGC in OFF as it's not really usable receiving different signals with different intensity.

RF potentiometer to attenuate the gain, I will evaluate in the future if I'll need to add it as well. Thanks for these advises....

For me is still a question why I'm not getting any signal showe on the SMeter connecting the A7 to the AGS circuit of Kit-Project...

73
Giuseppe IZ4JUK

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