6867	2011-11-23 18:38:57	wb8yyy_curt	Hybrid Cascode AGC
Message	Date	From	Subject
On my hybrid cascode amplifier I am only noticing a small change in AGC voltage with signal level. With band noise only the AGC voltage is running 3.9 volts, and it only reduces by 0.3-0.4 volts with a super loud signal input. As far as I can tell the detector circuit and the two transistors stages are wired correctly. Voltage threshold is set for around 0.4 volts. Any suggestions on how to further debug appreciated. 73 Curt
6871	2011-11-24 02:58:05	Fernando Krouwel	Re: Hybrid Cascode AGC
For those interested about a commercial use of the hycas, take a look at the following link: http://www.cumbriadesigns.co.uk/images/T2/T-2%20v1_2.pdf It is a (now retired) kit of a transceiver mainframe, but a good example. 73' s Fernando - PY2ETT
6873	2011-11-24 07:48:15	g3zoh	Re: Hybrid Cascode AGC
Hi Curt, I recently built a multiband HF receiver using the HYCAS IF module at 8 MHz and am experiencing exactly the same issue as you. Overall IF gain is more than adequate but the AGC does not seem to be working properly. Any guidance from this Group would be much appreciated. Brian G3ZOH
6879	2011-11-24 12:10:43	g3zoh	Re: Hybrid Cascode AGC
Hi Curt. Your post encouraged me to have another look at my HYCAS-based receiver this afternoon. After resoldering some joints on the HYCAS board and realigning the receiver, AGC measurements are now :- IF Gain to min with no antenna attached - AGC = 1.0 volts IF Gain to max with no antenna atttached - AGC = 5.9 volts IF Gain to max with antenna attached but no signal - AGC = 4.6 volts IF Gain to max with test oscillator at 14 MHz loosely coupled to antenna socket - AGC = 2.7 volts So the AGC does now appear to be working! To be honest, I am not too sure what was wrong before - apologies, as I should have experimented a bit before "jumping in with both feet" and posting a response on the List. There is still a higher than expected background noise level when receiving weak or moderate strength signals which could of course be attributable to other parts of the receiver. Turning down the IF Gain helps a lot and R6 (threshold resistor) is currently shorted, as per the option in the instructions. I may play around with R6 tomorrow. Good Luck Curt and feel free to come back if you want to compare any other voltage readings
6880	2011-11-24 14:59:05	R Wall ML emails	Anyone have a DSPx and KDSP10 for sale...
Hi all, Does anyone have a DSPx daughter board and it’s KDSP10 interface mother board that they would like to sell. I want to have a go at DSP programming and to see if I can use the 17 meter DSP transceiver code that is in the EMFRD book with a softrock I/Q transceiver. I want to also use it for transceiver audio noise reduction that is in another yahoo group. Thanks for your help, Roderick Wall, vk3yc. [Non-text portions of this message have been removed]
6902	2011-11-26 17:21:55	ehydra	Re: Hybrid Cascode AGC
Interesting inside around Q4 and Q5. Any idea how this works? - Henry Fernando Krouwel schrieb: > For those interested about a commercial use of the hycas, take a look at > the following link: > > http://www.cumbriadesigns.co.uk/images/T2/T-2%20v1_2.pdf > > It is a (now retired) kit of a transceiver mainframe, but a good example. > > 73' s > Fernando - PY2ETT -- ehydra.dyndns.info
6904	2011-11-26 17:34:41	Thomas S. Knutsen	Re: Hybrid Cascode AGC
It's an PIN switched bi-directional amplifier. Since it only receives DC at one side at the time, and those are newer both on, it would work to switch the direction of the amplifier. I have built one of those kit's, the idea is that it should become an 144MHz transverter IF. 73 de Thomas LA3PNA/AE5YS. 2011/11/24 ehydra <ehydra@arcor.de> > ** > > > Interesting inside around Q4 and Q5. Any idea how this works? > > - Henry > > Fernando Krouwel schrieb: > > > For those interested about a commercial use of the hycas, take a look at > > the following link: > > > > http://www.cumbriadesigns.co.uk/images/T2/T-2%20v1_2.pdf > > > > It is a (now retired) kit of a transceiver mainframe, but a good example. > > > > 73' s > > Fernando - PY2ETT > > -- > ehydra.dyndns.info > > > -- Please avoid sending me Word or PowerPoint attachments. See <http://www.gnu.org/philosophy/no-word-attachments.html> [Non-text portions of this message have been removed]
6922	2011-11-27 09:43:10	kb1gmx	Re: Hybrid Cascode AGC
With 100-120db of gain care in parts placement and also external wiring to the filter at the input are very, VERY, important. Same for wiring, short leads and use of shielded interconnects off board. Also pay attention to the inductors used, some chokes are not well shielded and also solenoid coils of open design are to be avoided or careful shielding applied. If you seeing volts and noise with no RF input likely it's oscillating at some other frequency. I've used the hybrid cascode configurati