开云体育

A YO3DAC article to understand how an AGC circuit works and the difference with a VGA circuit!

#ubitxv6 #ubitx6-help #v6

Loris Bollina Member Profile All Messages By This Member #89855 Just to clarify that the circuits generally appeared in the group and in the WEB (e.g. the ND6T circuit), ARE NOT AGC CIRCUITS, but normal RF ATTENUATORS with a big defect, even in the MINIMUM ATTENUATION position, involves a loss of 3dB on the input signal to the RX (loss of 50% of the signal) with strong reduction of the sensitivity of the ?BITX, it seemed useful to me to give everyone the opportunity to read the article by YO3DAC which gives a correct and detailed explanation on how to build and insert a TRUE AGC in a receiver. Kind regards from IW4AJR Loris AGC in Receivers by YO3DAC.pdf AGC in Receivers by YO3DAC.pdf
iz oos All Messages By This Member #89869 Loris, you are right! 50% of loss is a lot! If I used 500w, I wouldn't like to loose half of the power warming the climate... But 3db in RX is usually negligible and I find the ubitx (I have ver.3) sensitive enough. I wouldn't worry about a 3db loss, at all. So, as my unit has not any sort of RF attenuation, I will look with interest ND6T add on. Thank you for the hint! toggle quoted message Show quoted text Il mar 17 ago 2021 06:37 PM Loris Bollina via <lorisbollina=[email protected]> ha scritto: Just to clarify that the circuits generally appeared in the group and in the WEB (e.g. the ND6T circuit), ARE NOT AGC CIRCUITS, but normal RF ATTENUATORS with a big defect, even in the MINIMUM ATTENUATION position, involves a loss of 3dB on the input signal to the RX (loss of 50% of the signal) with strong reduction of the sensitivity of the ?BITX, it seemed useful to me to give everyone the opportunity to read the article by YO3DAC which gives a correct and detailed explanation on how to build and insert a TRUE AGC in a receiver. Kind regards from IW4AJR Loris
Loris Bollina Member Profile All Messages By This Member #89872 Hello iz oos, I did the tests! ... inserting the ND6T attenuator into the ?BITX is tantamount to committing suicide! I have a ?BITX # 6 that works very well even with very low signals (S1 and S2) and I assure you that the data declared by Ashhar Farhan are abundantly respected. When I inserted the DiY Kits circuit (AGC?) The RX became "deaf as a pot", in fact, like many RF variable "attenuators", the 3dBs are just a "theoretical illusion", actually the ND6T circuit loses quietly 12 to 18dB (i.e. 2 to 3 S points). the reason lies in the type of active elements used (MOSFETs) which have insertion losses, at the minimum driving voltage (maximum AGC voltage), infinitely higher than the RF attenuators integrated with PIN diodes (eg BAP64Q) which in any case lose from 4 to 6dB at maximum driving current. If you want to try a slightly more serious AGC I recommend the one from INKITS ( ) which, acting on the gain of the second IF, works as a true AGC and does not desensitize the receiver, even if it takes the signal from the BF and not from IF. A very varied greeting de IW4AJR Loris ? BAP64Q.pdf BAP64Q.pdf
Gerard All Messages By This Member #89873 Loris, ?look here the pdf file also look here? ??[email protected] \| a little question on AGC and search the Barry AGC? like that ** Gerard, attached is the way I have this AGC connected to my V6. Barry K3BO ? ? toggle quoted messageShow quoted text ? ? cdt AGC.pdf AGC.pdf
Loris Bollina Member Profile All Messages By This Member #89874 Hi?Gerard OK ... That's what I recommend! The great advantage of this circuit, compared to an attenuator in the antenna input, is that this AGC manages the gain of the second IF and does not attenuate the input signal! hi Gerard .. 73 de IW4AJR
Earl Cox #89876 Apparently, The link to the agc download installed an app on my computer that wanted access to my passwords then popped up again after I shut it down. Earl Cox? KB5UEW? Reply or E-mail me at:? kb5uew@... On Thursday, August 19, 2021, 02:49:32 AM MDT, Loris Bollina via groups.io <lorisbollina@...> wrote: Hello iz oos, I did the tests! ... inserting the ND6T attenuator into the ?BITX is tantamount to committing suicide! I have a ?BITX # 6 that works very well even with very low signals (S1 and S2) and I assure you that the data declared by Ashhar Farhan are abundantly respected. When I inserted the DiY Kits circuit (AGC?) The RX became "deaf as a pot", in fact, like many RF variable "attenuators", the 3dBs are just a "theoretical illusion", actually the ND6T circuit loses quietly 12 to 18dB (i.e. 2 to 3 S points). the reason lies in the type of active elements used (MOSFETs) which have insertion losses, at the minimum driving voltage (maximum AGC voltage), infinitely higher than the RF attenuators integrated with PIN diodes (eg BAP64Q) which in any case lose from 4 to 6dB at maximum driving current. If you want to try a slightly more serious AGC I recommend the one from INKITS ( ) which, acting on the gain of the second IF, works as a true AGC and does not desensitize the receiver, even if it takes the signal from the BF and not from IF. A very varied greeting de IW4AJR Loris ? BAP64Q.pdf BAP64Q.pdf
Gerard All Messages By This Member #89877 Hello Earl What link exactly ??? I have tested my file with antimalware and Microsoft defender, no problem. cdt
Earl Cox #89881 ?? When I downloaded it then tried to run it my antivirus spoke up as mentioned. Earl Cox? KB5UEW? Reply or E-mail me at:? kb5uew@... On Thursday, August 19, 2021, 10:36:54 AM MDT, Gerard <kabupos@...> wrote: Hello Earl What link exactly ??? I have tested my file with antimalware and Microsoft defender, no problem. cdt
Loris Bollina Member Profile All Messages By This Member #89885 Hello Earl, try to go in the home page (??) and after go in Store and you?search and click "General Kits" the AGC is the "AGC KIT For Bite And uBitx" is the first item ... click on price ($29.00) it should work! 73 de IW4AJR Loris toggle quoted message Show quoted text On Thu, Aug 19, 2021 at 08:28 PM, Earl Cox wrote: https://amateurradiokits.in/product/agc-kit-for-bitx-and-ubitx/
George Metaxas (SV1DEQ) All Messages By This Member #106260 Hi Loris, I have installed that circuit on my uBitx v5 and have not noticed any significant reduction in volume in the presence of a strong signal. Maybe I have tied that to the first IF instead of the second? I should have a detailed look at that. I even changed the op amp IC from the LM324 to the TL084 but noticed no difference. PS: Do you or anyone happen to know where I can find a nice panel microammeter like the one supplied with that AGC circuit? 73, George, SV1DEQ

Previous Topic Next Topic