I vote for subgroups - PLEASE!

Allison

If the IMD were "perfect" you would see two tones, period. :-)

WA8TOD

Nikos,? I do have the 3.5" Nextion display (….T035-011) and would love to have the files (you can send them to jlauber@...).? As for changing the x,y, h and w values, in the Nextion editor, click on any element of the display, and the Attribute page for that element pops up...scroll down to the bottom of the list and you'll find x, y, h and w and you can simply edit them.? But getting the right values to put in those is the devil in these details!

73
John

Warren,

To that we are both in the same pew.? Bandaids are turning to cardiac surgery.
Unfortunate that that is the case.

I've gone back to modernizing a old atlas that was a parts dog for fun.
A display, Arduino, and 5351 can do a lot for that one.?

Allison

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That assumes that the end users would use them properly. Its already impossible to get a thread to stay on topic. You can always set a thread to be muted if you don't want 300 messages regarding efhw antennas. Besides, who is going to do the labour required, you?

A great example is the same thread coming back even though a group was created for antennas. Nice idea, hard to implement.?

-- If there were only a couple messages a day it might make sense to keep everything together.? But I have received over 3000 digests, and it has become nearly impossible to determine which flavor BITX the messages are for.? I have a Bitx20, Bitx40 and a uBitx , it would be nice to not have to wade through all the messages and ignore the 300+ messages about End Fed antennas to find information related to my Bitx40.? ? I belong to other Groups that have sub-groups and they work well for keeping things a little more organized.
DuWayne? KV4QB

Alison

i have put my uBitx on the shelf and plan no further work on it. Just too many issues trying to make a Ford out of a tricycle. I put these up as an assist for those still trying.?

WA8TOD

Warren,

That is indeed a mess.

One place to look is pull power to the amp.? Look at the output of the 9 element 30mhz filter
peak level should be under -10dbm.? ?The stuff you will see there is not good and varies
with CW and SSB.? ?Then look before the filter (with it disconnected).? IF you look at both
those spots with and with out the power amp operating you also get a different mix of
spurs with different amplitudes.? ?It is especially bad above 17M.? You get at the output
of the 34mhz low pass a mix of signals that changes if the power amp is working into
a dummy load or turned off.

It suggests unwanted coupling and board level current loops.? It appears to be some of it
is signals introduced into the 45mhz wide band amp after the crystal filter.??

The 30mhz low pass was stated as not being adequate from testing then and
would found to be so again.

7/28/2016 part of the email stream at the beginning on freelists.
For myself I'd grab a bag of latching relays and build band specific filters.? That we know
can work but while its repetitive circuits is not always simple to do well (or tune up).

Back then I was told I didn't know shit and so I stopped saying it as was not to beb said
I had all the work and testing on a bench proto to the contrary.? Back then it was
failed TRX Minima as it has all sorts of unwanted outputs using a 20mhz IF and
minimal filtering while trying to cover 3-30mhz.? ?That begat HF1 Dual conversion
with crystal oscillators for CIO and 2nd conversion from a two pole 45mhz LC filter
and morphed into beginning of uBitx by early 2017.? ?The first version only had
2 than a bit later three low pass filters for 3-30mhz.? The goal then was as is
now 3-30 and very few filters.? Parts availability were big divers as in variable
caps and coils.

Allison

Distortion is the likely animal.?

If its more than 40db down that is not bad and not to worry about it.

To see IMD you need two equal tones inside the filter pass band with non harmonic relationship.
I use a 750hz and 1750hz as thse are in the typical voice bandwidth.

IF the IMD were perfect you see two tones in the sideband and much weaker ones
(more than 40-50db down) in the apposing sideband.? IF the IMD were poor you see
a flock of new tones (750+1750 and 750-1750 and harmonics of those) with varying
amplitude inside the filter pass band and outside of it.

Allison

There are other versions of 2n2222 in SMT, DXT2222.

The MMBTh10 is better than the 3904 as is the SMT 2n2369 (mmbt2369) and BFR106.

As to voltage that spot (Q90)should not see more than maybe 16V ever.

Allison

Mag loops...? Mis named.? ?Resonant small loop.

They run about -12db on 40M for a soso one and maybe -10db for a good one
compared to a dipole at 40ft or more.? This is for a 1M diameter loop at 40M? ?
The problem is radiation resistance is so low and other resistance in the
build can be significant.? Go up in frequency? Efficiency goes up but 80% is peak
as then you get to effects of uneven current distorting the pattern.

However the better the loop is the more tuning required as the bandwidth is narrow.
good for spurs and all and compact but like all small antennas (less than 1/10th
wavelength) they are inefficient.?

Its advantage self completing antenna, small,? has good null that can
help with noise reduction.

Oh we had a CME hit Saturday turning the bands upside down.

Allison

On Tue, Aug 28, 2018 at 08:48 AM, Ajay Kashikar wrote:

Can some one (who has used Myantenna or 49:1 home brewed EFHW antenna) share the experience if it was not working or any remidial action taken (added tuner) and which made it functional.

Ajay,
The map below shows most of my QSO's with a Myantennas EFHW-8010P fed with 50' RG8X direct from my ?BITX.

?
--

IF we don't take advantage of groups.Io for other topic centric groups we end up with mush.

Why do that?? Because people interested in antennas and not bitx interest will likely not look here.

Might as well start talking about old computers here rather than vintage computers forum.
After all the uBitx has a MPu and many of us worked with computers.

Allison

Ajay,

Just one clarification: You may use a 49:1 transformer or you may use a tuner. You do not need both.

Have fun!

WA8TOD

There is already a homebrew group and an antennas group. Splitting the radios up would just make a mess of things.

Vince - K8ZW.

--
Michigan VHF Corp.

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Cheers!