Fantastic.  Thank you for your help.

73,
AE6HR

Well, I think you understood me.  I am wanting to use the PIC that controlls the PLL and DDS in this design I am working on to control the amount of RF power that goes out to the antenna.  However, I would like to be able to digitally control that level so that I don't need a watt meter built into the radio.   Is that more clear?

I believe your answer is what I am looking for.  So, the place to put this "pin diode series modulator" would be in one of the final RF amp ALC driven stages before the driver and the PA?  Am I understanding that correctly?

Yes, I am trying to learn from books too.  I have one on Basic Electronics, Basic Communications, Basic Digital Electronics (all from Master Publishing).  They are helping some.  Still haven't worked through them all the way yet.

Thank you WB2WIK/6,
AE6HR

I realized as I was sleeping that my original post may seem critical of OZ2CPU.  I didn't mean to sound that way.  The radio is his project and is a work in progress.   There probably are things he hasn't shared that he has built.  I am just starting from where he was when he last put things up.

It is a cool site anyway.... http://www.webx.dk/oz2cpu/20m.htm is the site.

I still would appreciate any help people can offer.

73,
AE6HR

As mentioned in another post, I am making a radio based (largely at the moment, getting less all the time) on OZ2CPU's homebrew 20meter SSB rig.

His rig as is, seems to make assumptions that don't hold true, like the fact that he must be using the sum out of the final mixer to drive 6 meters, but his filter in his RF amp is low pass.  He also hasn't designed for 160m, I am trying to rework it to do so.  I do believe a single low pass filter after the final driver or PA (depending on how it is running) is good.  However, before that stage, I need to remove the appropriate sum (sum or difference) from the mixer.

I will be using a push-pull based A or AB driver and PA, so I believe things should be fairly linear.  The radio is DDS based, so their shouldn't be tons of noise or spurious signals.

So, am I correct in believing that right after the final mix (before the RF amp, driver and PA) is the only place I need a band pass filter?

If so, here is my problem.  I was discussing one solution with a friend who has much more electrical design knowledge than I have.  Here was my idea...

Since the radio is PIC based and controlled, it would be nice for it to automatically select the band pass filter.  I thought an array (parallel filters) of band pass filters coult be switched on and off individually by the CPU using two transistors each (one for each half of the wave).  The PIC would drive the GATE, the (using FET terms, since I am not good with the normal ELC terms yet) source would be the input radio signal, and the drain would be the ouput into the RF amp, etc.

I was told this would work.  However, this adds losses and stray capacitance.  Also, I was told the transistors would need to be rated for the 100% duty cycle.  I am not sure relays are the answer.

Any help available from you great folks?

Best wishes and many thanks,
Trever Adams - AE6HR

Bad subject, I know.  However, I am not sure how else to sum this up.

Many of the comercial radios allow you to select your output (TX) power to a fairly fine grained level it seems.  I am working on making a radio, somewhat based on OZ2CPU's home brew with a lot of ideas I am learning as I work.  You see, I am one of these nuts that just went and took all the tests and passed.  Now, I really want to learn and experiment.

I am having a difficult time (even with referencing the HUGE schematics for ICOM 756 and 706MKIIG) figuring out how to select the power ouput.  I can find some drivers that will that the .01-.5 watt output of some circuits and amplify it to 20 watts. I can find ones that will take that one (if it is at about 5 watts) and amplify it to 100+ watts.  These are all great, but I am having a difficult time.

You may just say potentiometer on the center tap (push-pull), however, this radio is PIC controlled.  I would like the power level to be controllable and knowable by/to the PIC.  I have found some digital potentiometers, however, they can't handle the current needed in most amplifiers (push-pull for example), and they probably have much too high resistance (10k-50k+).

So, solution needed: Digitally controled the gain on the driver (thinking of that one that goes up to 20 watts, need to drop it to 5 to feed the larger one when appropraite), and a digitally controled gain on the PA.  If the PA can be driven such that a gain control on it isn't needed, that is fantastic.

This does indeed sound like it, based on the webpage.  KE6RIE Straight Key seems to be the one.  I wish I could find out for certain if this is indeed it.

Any World Radio subscribers out there have late issues of 2002 and are willing to check it out?

So where does one find a "complete" Morse code sheet.  I have a few books, but they only cover A-Z,1-0, and a few prosigns.

In a World Radio magazine from late 2002 (I believe it may have been November; no later than December and no earlier than August), I saw a review of a blue anodized code key that was small, but balanced so it didn't slide around.  Apparently it is one person making these.

I meant to keep the review, but I accidentally disposed of the magazine before I took it out.

Does anyone have the details on this?

73,
Trever Adams - AE6HR

P.S. Yes, I have tried contacting World Radio, no response... which is understandable.

Thank you very much to all of you who answered.  Some of you did a wonderful job of helping me find information.  I am trying to located the appropriate periodicals or books at this moment.

Cheers.

I am the grandson of a WWII Army Aircorps gunner.  Because of this, and my father's insane interested in history (it is contagious you know), I have done a lot of reading about the different wars as well as watching those wonderful (??) documentaries on various history channels.

Quite often, both my father and I, have heard of POWs making receivers or tranceivers (in rare cases) from things they could scrounge in some of the war prison camps they were in.  I have spent some time, so has my father (who isn't a HAM [yet], but once was GROL, back in his college years), trying to find information in books or on the INTERNET about such feats.  I would like to find information that gives how some of them accomplished this.  I can see them getting their hands on things to be inductors and capacitors, but have had a hard time figuring out crystals (if used), resistors, and other required parts.

Does anyone know of such reference material?

73,
Trever Adams
AE6HR