Date   
Re: RD16HHF1 power curve flattening...some

Kelly Jack
 

Bill,

Does this mean that a different compensating capacitor is required for each band   ie. To get the 20w on each band?

Regards

Simon
VK3ELH

Re: Strong carrier on transmit. #bitx40help

 

Bob,

The carrier burst occurs because the c122 is charging up on TX through D15, causing the mixer to unbalance momentarily.

Solution is simple:

Cut the track from D15 and D16 common that goes to R38 and 39 and scrape the green paint off the cut track ends and solder a
0.1uF capacitor. Additionally add a 1K across C107 to provide a DC path.

Raj

Re: RD16HHF1 power curve flattening...some

John <passionfruit88@...>
 

Hello Simon,

My understanding is that the value of the capacitor gives the peak of the very broad resonance. Therefore you choose where to increase the gain the most and select the capacitor accordingly.

73, John (VK2ETA) 

I want to know when uBITX is coming ? (Invalid address)

Bae hwangchan
 

Hello

My name is Hwang-Chan  Bae.
We have paid $ 109 to Paypal as a credit card to DEC-21-2019 to purchase uBITX.
But uBITX has not arrived yet.
I want to know when it is coming.
Receipt Number: 5494-5763-6907-3144.
name: Hwang-chan  Bae
Address: Bansong Road 177 (205-1104) Hyundai Apartment
Changwon City Seongsan-gu, Gyeongsangnam-do
51425
Republic of Korea.


Please let me know when you arrive.







Re: Three (and a Half) AGC schemes #ubitx-help

John <passionfruit88@...>
 

Thanks Jerry for that information.

I have a better understanding of the constraints and benefits of IF AGC now.

My personal preference when listening on speakers is for a strong AGC where the volume is pretty constant and the noise is simply "pushed down" on the reception of strong stations.

I agree that for headphone operations a simple limiter is useful and sufficient.

In line with what you say about the location of the AGC in my experiments I did connect the drain of the 2N7000 to the base of Q70 via a resistor and capacitor but I must have had too much gain in the loop and created massive audio feedback, and just dismissed that option.

I also read on the internet that distortion can be reduced if the audio voltage is small, so I definitely need to re-visit that option.

Thanks and 73s, John (VK2ETA)

Re: Strong carrier on transmit. #bitx40help

Allard PE1NWL
 

Alternatively, install the latest Raduino sketch which eliminates the RF-burst by software:
https://github.com/amunters/bitx40

73 Allard PE1NWL

Re: Three (and a Half) AGC schemes #ubitx-help

DF1EA@...
 

Hello,

look here : http://www.qrpproject.de/Media/pdf/Mosquita40.pdf.

The tranceiver use a TCA440 / A244 as audio preamp with gaincontrol. It should be possible to use the audio part in the ubitx.

73 de df1ea, Chris!

Re: Three (and a Half) AGC schemes #ubitx-help

MVS Sarma
 

Chris,
Any thing couild be used. IMHO, Simopler circuitry bring better stability.
Just for sake of modding we don't have to.
RegaRDS
 SARMA
 VU3ZMV

Regards
MVS Sarma
 

On Mon, Feb 26, 2018 at 5:04 PM, <DF1EA@...> wrote:
Hello,

look here : http://www.qrpproject.de/Media/pdf/Mosquita40.pdf.

The tranceiver use a TCA440 / A244 as audio preamp with gaincontrol. It should be possible to use the audio part in the ubitx.

73 de df1ea, Chris!


Re: Looking for Completely Functional Dual-Band 20/(17/15/10/6) Meter QRP Rig with SSB/PSK #bitx20help

Mark KC1JCD
 

Hi Tim,

There most definitely has been. I did not expect such support!

In addition to learning about antennas, it might be a good idea for me to get more familiar with some of these terms. It's like learning a different language.

Mark

Re: Looking for Completely Functional Dual-Band 20/(17/15/10/6) Meter QRP Rig with SSB/PSK #bitx20help

Mark KC1JCD
 

Hello All,

Even though I may not be making a uBitx, I have learned a lot over the last couple of days. I copied these most important messages to my HAM text file.

With more study, I can probably answer many of my questions on my own. I have a list of material that is "next up" for me to absorb.

Books & articles are nice. Yet, there is nothing like having access to a community of people who have traversed the path, & are willing to share their experiences.

You have been very kind to me. :)

I don't want to keep distracting you all with these questions & comments that are obviously far below your level of expertise.

I'd rather not tie-up the groups.io/g/BITX2 anymore, that is devoted to BiTx, with basic questions about antennas.

Right now I'm searching groups.io for other amateur radio groups to join, using these key words: amateur radio; HAM; antennas; QRP; etc.

Who knows, maybe I'll be communicating with some of you.

HAMs are a great bunch.

Thanks!

Mark

Re: RD16HHF1 power curve flattening...some

K9HZ <bill@...>
 

In order to be perfectly flat in response... yes.  Practical... no.  I would try 330pf and stick with that because you naturally have more gain  at lower frequency anyway. 


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com


email:  bill@...

 


On Feb 26, 2018, at 12:47 AM, Kelly Jack <kellyjack1968@...> wrote:

Bill,

Does this mean that a different compensating capacitor is required for each band   ie. To get the 20w on each band?

Regards

Simon
VK3ELH

Re: Looking for Completely Functional Dual-Band 20/(17/15/10/6) Meter QRP Rig with SSB/PSK #bitx20help

Vince Vielhaber
 

Every group has their self appointed moderators that think their opinion should be the rule. I just skip over them as I do the threads or posts or posters I'm not interested in.

Vince.

On 02/25/2018 11:39 PM, Jerry Gaffke via Groups.Io wrote:
There are plenty of threads here I'd just as soon skip over, and often do.
Perhaps you can do the same.
I for one am fine with discussions of antennas (that seems very
appropriate)
and with discussing the pros and cons of the Bitx radios vs others.

Jerry, KE7ER


On Sun, Feb 25, 2018 at 08:13 pm, Rod Self wrote:

I, for one, am very tired of off-topic general discussions about
radios and antennas on the bitx20/ubitx group.

Please let this thread die, or move it to another discussion group.

A good guideline: if it does not involve a bitx or utibx, it
probably does not belong here.

bitx40 finished

_Dave_ K0MBT
 

A couple of weeks ago I saw a fellow hams bitx40, he had ordered a ubitx but had not received it. I went home and ordered a ubitx and started the wait. I found a bitx40 for sale and obtained it. Put it together. It actually receives. I don't have a decent antenna yet for it and have not tried tx with it. 

There seems to be a fair amount of whistles in it with the main one at 7.195 or so. That is my only complaint. 
Dave

Re: Raduino Replacemnt, COMING SOON!

César EA3IAV
 

Hi! I would like the through hole board !

Re: #ubitx How to interpret serial number #ubitx

Jason Schlager
 

My thoughts:
First character is who inspected the unit.
The number in the middle is the sequential number of units that passed inspection.
The /1 or /2 at the end is the batch #.
--
Jason Schlager
KM6AUS

Re: Looking for Completely Functional Dual-Band 20/(17/15/10/6) Meter QRP Rig with SSB/PSK #bitx20help

Neil Martinsen-Burrell
 

[I think that this reply is completely on-topic for a BitX list.]

Mark,

I keep a list of all of the QRP transceivers that I know of that are currently for sale: https://docs.google.com/spreadsheets/d/1VA9paN2Hcs5NEhi8x9lFV2bmX-lR7HDK7kQnuQ1u6rA

As you can see from the list, the uBitx is the least expensive choice that includes SSB. For that low price, you need to do some simple assembly (not building the entire radio which many of the other kits around that price require). The QRPver that you mention is around the same price as the YouKits SK-1A which is a similar fully-assembled monoband 40m radio.

Any other multiband SSB-capable radio that I know of is SIGNIFICANTLY more expensive than a uBitx. The YouKits TJ2A, TJ2B, and the Xiegu X1M are the next tier of
 possibilities at over $300.

I have found that being able to review the whole range of available products can give good perspective on how one product stands in relation to other choices.

If anyone here knows of any other frequency agile, CW-capable QRP transceivers that are currently for sale but don't appear on that list, let me know (neilmartinsenburrell@...) and I will add them.

-Neil N0FN

On Mon, Feb 26, 2018 at 6:38 AM, Mark via Groups.Io <mboston72@...> wrote:
Hello All,

Even though I may not be making a uBitx, I have learned a lot over the last couple of days. I copied these most important messages to my HAM text file.

With more study, I can probably answer many of my questions on my own. I have a list of material that is "next up" for me to absorb.

Books & articles are nice. Yet, there is nothing like having access to a community of people who have traversed the path, & are willing to share their experiences.

You have been very kind to me. :)

I don't want to keep distracting you all with these questions & comments that are obviously far below your level of expertise.

I'd rather not tie-up the groups.io/g/BITX2 anymore, that is devoted to BiTx, with basic questions about antennas.

Right now I'm searching groups.io for other amateur radio groups to join, using these key words: amateur radio; HAM; antennas; QRP; etc.

Who knows, maybe I'll be communicating with some of you.

HAMs are a great bunch.

Thanks!

Mark


Re: Three (and a Half) AGC schemes #ubitx-help

Jerry Gaffke
 

The 2n7000 reduces gain when high signal strength is detected, and so is effectively a 180 degree phase shift.
There will be delay through the audio preamp stage, the agc detector, and that 2n7000,
a safe bet the audio squeal you heard is at a frequency for which this delay is an additional 180 degrees,
making a dandy oscillator.

Buried in that old thread started by Henning about dynamic range in the audio preamp is discussion
of using a pin diode attenuator at RF, perhaps the very cheap BAP64Q.
    https://groups.io/g/BITX20/message/32090

There are other such pi network pin diode devices available.
The charge carrier lifetime limits the lowest frequency of operation.

Henning warns us that delays through crystal filters can impact AGC performance, so that diode attenuator
might best be placed somewhere between the 12mhz filter and the demodulator.
    https://groups.io/g/BITX20/message/32090

Pin diodes are also discussed here:
  https://groups.io/g/BITX20/message/31832
and here:
      https://groups.io/g/BITX20/message/42437

Jerry, KE7ER



On Mon, Feb 26, 2018 at 02:07 am, John wrote:
In line with what you say about the location of the AGC in my experiments I did connect the drain of the 2N7000 to the base of Q70 via a resistor and capacitor but I must have had too much gain in the loop and created massive audio feedback, and just dismissed that option.

Re: bitx40 finished

Jerry Gaffke
 

The birdie at around 7.2mhz on the Bitx40 is due to the 2'ed harmonic of the 12mhz oscillator
beating with the 5'th harmonic of the 12.0-7.2=4.8mhz vfo.    2*12=24mhz= 5*4.8

The cure is to use Allard's v2 firmware which allows the use of a high side vfo at 12+7.2=19.2mhz.
Some minor hardware mods are required.
    https://github.com/amunters/bitx40-raduino-v2

Though curiously enough there can still be a weak birdie at 7.2 due to higher order harmonics:
    5*19.2=96mhz=12*8

Jerry, KE7ER


On Mon, Feb 26, 2018 at 07:23 am, <davesters@...> wrote:
There seems to be a fair amount of whistles in it with the main one at 7.195 or so. That is my only complaint. 

Re: Looking for Completely Functional Dual-Band 20/(17/15/10/6) Meter QRP Rig with SSB/PSK #bitx20help

Mark KC1JCD
 

Neil,

Very much appreciated. I'm having a look at that right now.

Mark

Re: Raduino Replacemnt, COMING SOON!

LKNDAVE
 

i'll take 2 of the non-cap boards rather than you tossing them. i found the omission and had a solution for it already. send quote and i will buy 2. 1 hpf and lpf and audio too. i hope they are the ad8307 version.
dave