Message	Date	From	Subject
12693	2016-04-21 08:52:47	Rod KM6SN	LA3PNA all pass board
Greetings Thomas LA3PNA Thank you for posting the allpass PCB design on July 29,2013. I would like some information about the stages after the audio gain balance pot. Is there a printed article you could refer me to? Thanks, Rod KM6SN
12694	2016-04-21 09:26:22	Thomas S. Knutsen	Re: LA3PNA all pass board
I must admit that I needed to go back into the discussions we did in 2013, there have been some projects after that. The amplifiers are just that, regular inverting op-amp audio amplifiers. The first is the summing amplifier, the last is a regular audio amplifier. I beleve the capacitor C12 should be less than the value given in the schematic, this sets the bandwith of the amplifier. A quick simulation in any decent program (I preferar QUCS) would give gain and bandwith. Use good, low noise OP-AMPs and high presision resistors and capacitors to get the best preformance. My first board was used with a mixer chip at 1296MHz, if you are using a diode ring mixer you would probably need a common base amplifier to do the impedance matching at the IF. A decent common base amplifier should precent 50 ohms to the mixer from 100Hz or so to 50 or 100MHz, depending on device and gain. I beleve the inspiration for the board was a schematic in the lecture Rick KK7B did at FDIM in 2013, you can find the slides here: http://web.cecs.pdx.edu/~campbell/HardRockTalk.pdf I beleve the lecture was recorded, so perhaps one could get a copy. I would also reccomend to look into the recent discussions on the R2PRO yahoo group. It has some great discussions on both a interesting mixer topology and on the allpass filters. The best reference I can think of is the EMRFD. In addition, there are gold in the e-mail archive both here and in the R2PRO group, But the most important part is to do the experiments! Audio amplifiers have the nice benefit that a computer with soudcard can give incredible analyzis tools with free software. 73's de Thomas LA3PNA. 2016-04-21 14:01 GMT+02:00 Rod KM6SN rod.km6sn@wildblue.net [emrfd] <emrfd@yahoogroups.com>: Greetings Thomas LA3PNA Thank you for posting the allpass PCB design on July 29,2013. I would like some information about the stages after the audio gain balance pot. Is there a printed article you could refer me to? Thanks, Rod KM6SN

I must admit that I needed to go back into the discussions we did in 2013, there have been some projects after that.

The amplifiers are just that, regular inverting op-amp audio amplifiers. The first is the summing amplifier, the last is a regular audio amplifier. I beleve the capacitor C12 should be less than the value given in the schematic, this sets the bandwith of the amplifier. A quick simulation in any decent program (I preferar QUCS) would give gain and bandwith.

Use good, low noise OP-AMPs and high presision resistors and capacitors to get the best preformance.

My first board was used with a mixer chip at 1296MHz, if you are using a diode ring mixer you would probably need a common base amplifier to do the impedance matching at the IF. A decent common base amplifier should precent 50 ohms to the mixer from 100Hz or so to 50 or 100MHz, depending on device and gain.

I beleve the inspiration for the board was a schematic in the lecture Rick KK7B did at FDIM in 2013, you can find the slides here: http://web.cecs.pdx.edu/~campbell/HardRockTalk.pdf

I beleve the lecture was recorded, so perhaps one could get a copy.

I would also reccomend to look into the recent discussions on the R2PRO yahoo group. It has some great discussions on both a interesting mixer topology and on the allpass filters.

The best reference I can think of is the EMRFD. In addition, there are gold in the e-mail archive both here and in the R2PRO group, But the most important part is to do the experiments! Audio amplifiers have the nice benefit that a computer with soudcard can give incredible analyzis tools with free software.

73's de Thomas LA3PNA.

2016-04-21 14:01 GMT+02:00 Rod KM6SN rod.km6sn@wildblue.net [emrfd] <emrfd@yahoogroups.com>:

Greetings Thomas LA3PNA

Thank you for posting the allpass PCB design on July 29,2013.

I would like some information about the stages after the audio
gain balance pot. Is there a printed article you could refer me
to?

Thanks,

Rod KM6SN