The AM Forum

I have Dave's Valiant II, but Doug did not know the whereabouts of any paperwork on it's mods. I'm going to ask those who may have obtained some of his gear or paperwork to please look at it and if you happen to have any paperwork on this Valiant II please let me know. I would be glad to pay postage to get this back together with the rig.
If any of you know anything about what mods he did and could let me know, that would be very welcome. Thanks

I have Dave's other Valiant II which was modified extensively.

We took photos of your transmitter and I probably would have taken detailed photos of any obvious mods. I do not remember that rig having what looked like typical modifications.

There's a good sized folder here of Valiant II docs which came from Dave's stuff. I would be glad to help you figure out any missing information. Can you let me know what you are looking for? Is the transmitter working normally for you?

Dave W2VW

I'm in the process of building a new shack so I will not be able to test it for a while. This Valiant shows in the Pics supplied or seen from Doug an 8ohm input and as I could see a different modulation circuit. Door knobs for all high voltage rf output padding and coupling, Solid stating as well. Other than that I was hoping someone might have picked up his Valiant docs and they would alert me to what may have been done and I could trace it out. Thanks

Maybe I remember wrong which is certainly possible. The pix should show 2 different Valiant IIs. The one I have has no internal modulator at all and was externally modulated first by 811s and later a huge solid state deal. It also has no dial markings or lettering plus non standard color panel repaint.

Probably best to go to PM. I understand the delay due to your work.

If it has an 8 ohm input that usually means it wants drive from an external Hi Fi amp.  Sometime folks use an audio output transformer backwards as an audio interstage transformer.  In that case the modulators and modulation transformer would still be utilized.  The other possibility is that a larger audio output transformer is used as a modulation transformer.  In that case all of the audio power would be supplied from an external amp with a 8 ohm output.  If you look inside, it should be clear which way Dave had done it.  Many years ago Dave had modified his original valiant with the upside down tube circuit in the RF compartment to achieve high positive peak asymmetrical modulation.  I don't think that is the one you have. 

All the other cap mods and such just seem like upgrades and you should not have to fuss with any of that. 

Joe, W3GMS       

Now my question would be how it is setup, does it require 200W of amplfied input or 20W. As you can see in the attached Photo the 6146 modulators are still intact.

My Photobucket public account is still up and does have pictures so the rig was modified as you suspect.

The folders I have show a bunch of different setups over a lot of years.

Looks like you need drive power to the modulators from the pictures.

Let me look again at the folder to see if there is anything showing use of the factory modulators.

Just finished reviewing the entire folder. Nothing about outboard driving 6146 modulators.

Probably not too difficult to figure out what was going on though. More pictures close up would help.

When you get it going we can have a 2 way ZRF surplus QSO.

I can send both you guys some MP3 of Dave on those transmitters, and you could recreate and have him talking to himself.

I believe that would generate some good karma, ya know ?

I would like to have them to save on my computer, I might patch one through the audio chain one day for old times.

If you could take more pics of the chassis so we can see if the mic audio tubes are still in there and maybe some underside shots. This is a very simple design TX. There is a shield between the modulator tubes. That may be shielding the audio tubes and driver for the modulator. If they are still in their sockets, I would guess that the transmitter is ready to fire up.
If they have been removed, then the underside of the transmitter wiring will show that the drive for the grids of the 3ea 6146's will be a terminal strip on the back of the unit. Then you would go with a backwards connected audio output transformer hooked up to a 20-30 watt public address amplifier. I do not think Dave would have turned the transmitter into a thoughtless mess.
Fred

Oh no Fred, Dave did what was done on purpose and with great thought. I'm a drawing person, I don't like to guess at what was or might be, but in this case I'm close to having a limited understanding of what is. These are the pics.

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Hope this helps. As best I can visualize the Audio is fed in at 8ohms into a backwards tranny feeding the modulators. The rest of the mods are common powersupply and padder cap mods. Now there may be some bias changes I haven't fully ferrited out but that will be determined as I go along. I should fire it up this weekend and see how it does. If only the bands would be a little more accomidating.
I'm going to use a SDR receiver but I have to work out the muting method. Do you guys using these just open the output to the speaker or the input mic connection as well. Also do you run the output of the computer directly to the speaker or run it into a channel of the audio chain and out to the speaker??

The underside pictures are not very clear or bright. The AUDIO INPUT jack on the back of the TX gives us some hope.
You will have to trace those wires out and tell us where they go. If it's to a small to medium sized transformer, like the one I see marked 541 and some handwritten info. Trace the wires from that transformer and see if they head towards the three mod tubes.... THEN you would connect the output of an 8 ohm Public address amplifier or 8 ohm audio amp with a microphone mixer. An amplifier of this type needs a microphone input to properly match the microphone and give good audio response. Probably a 20-30 watt amp. You're not going to use all of that power, we are looking for something with 8 ohms out. But you still need a microphone input.
If that AUDIO IN goes to a tube socket THEN you would plug in a 1/4 inch phone plug with approx. 600 ohm microphone.

It is 8ohm audio in and here is the general drawing of what Dave did. So now I can relax because I understand what and how the Audio is fed. I am using a c1 into a mic amp, to a compressor/limitor into a Audio amp with digital EQ and out at 8ohms and supplying upto 75w. That ought to get this up and running.

Looks like you made some good progress.  To drive the grids of the 6146 you will need very little to drive them. 

I just got off the phone with Doug whom you bought the rig from.  What I was going to suggest is just to trace the secondary of the 8 ohm transformer, the high impedance side, and see if it goes to the grids of the 6146's or if its in series with the HV going to the final.  That would be a simple thing to do.  Now it looks like you have answered the question.  With going to the grids the bias voltage for the modulators is fed through the CT connection of the transformer so all three leads are used.   If it went to the HV in series with the final, only 2 leads of the transformer would be used.   

I would suggest you get a Valiant manual to see how to tune up the rig.  Its very simple but if you have not done it before it would provide the guidance.  Then after you get the carrier part right, then work on the audio set-up.  Should be a fun project!!

Joe, W3GMS

I had an original Valiant all stock back in the early days, All i did way work to keep it running and that was a learning experiance I miss. Looks like I found the drawings which match what is intact and now time to put the rest of the bench together and fire this up this weekend. Maybe the probigations gods will be kind and let me talk across the street.. Inverted Vee up at 70ft.
I'll be using my sdr ensemble II as a receiver, but I will need to build the T/R switch to drop the speaker out on transmit. I'll be pulling the relay out of an old amp with a base to see what I have to work with. If I don't have the parts I can always just manually unplug it from the computer.
I get a little worried about putting power to something I don't know or understand what has been modified from it's original design. But this ought to work out just fine.
Thanks for the input folks..

Anyone one have a nice Audio amp design for a computer soundcard input to a 8ohm output with about 10W of audio?? Or have a software link to design such a beast.

Try looking at a ham fest for an old tube or solid state P.A. amp with a microphone input? You're almost there.
Goodwill or a Thrift shop might have surprises too.
A lot of people, thankfully, discard sometimes perfectly good items, or items that are vintage and worth a lot of money.
A friend of mine is making a killing going to Goodwill or Salvation Army and finding little gold mines of stuff that he can push for a profit on Amazon. Many steps above eBay.
Fred

Fianlly got power to the gig last night and it has no grid drive. Being I have no real Idea what the status of the mods are I'll be laying her over for a full hand over hans lookie and document what I find on the drawing. I'm not sure if this was a back-up work in progress or what, so only time will tell. This will take time of which I have very little free time to work with. Might be I'll do it when I retire projects.

The normal stuff you should be able to do quickly.  How about XTAL operation any grid drive.  If yes, then you know where to look.  Check DC voltages which could tell you quickly if that is the problem.  A lot of time its the simple stuff.  Tube condition??  If you have a scope, see where your loosing the signal.  In a very short time you should be able to see if its something simple.  Don't forget about the cam slipping on the rotary switch shaft. 

Joe, GMS 

Hey W2VW would it be posible to get a copy of what you have so I can see where this Valiant might be in evolution of modification?? Electronic would be fine. Looks like the tracing will begin.

No crystals so no operation, but the VFO works fine with both Osc and Buff and I listened to it on the receiver. I'll have to look futher down the path and majke sure the jumpers are in the proper place and so forth. I got a heck of a dc shock working on an amp four years back, almost got to meet the gate keeper. So I'll be nervious as a nun in a %*(_ well you get the picture.
Funny I used to work on T3's and such in the military and have an instrument degree and I'm still poop'in my drawers everytinme I probe something with power on it. Guess you never get over that after the big ZAAAAPPPP.

The other option is to find a local ham and the two of you can work together on it.  In fact, when working around HV that is a good thing to do anyway.   Good on the lower level stages working.  Don't forget to look at the screen voltage on the driver tube. I believe it was done the same way on the valiant as the rangers and if that's the case, those WW pots do go bad.  Just stage by stage and walla,,,,,you will have success.  Methodical analytical approach.

Joe, GMS     

Once the ZRF Valiant is operating it would be prudent to change the modulator tubes to triode connected 6DQ5s or other similar types(6CD6-6CB5-6DN6-6EX6) All of these types are interchangeable in pairs as long as the pinout for the 6BG6 is observed when hooking things up. A reverse connected outpoot transformer,probably what's in there already will work OK. About 10 watts of audio is needed. The screens are directly driven.The CT of the driver transformer goes to ground. The grids are tied to ground as well. A string of plain old rectifier diode is wired in series with the cathode return in order to bias the tubes to a range of 50-70Ma. 6146s are not good audio tubes in tetrode configuration . In triode connected mode they will not be able to make full modulation. This has been tried before( PW Fallon valiant,1976) I gave him a pair of 6CD6s. End of low modulation problem. Next step would be a real modulation transformer. You could turbo connect (Auto transformer)the stock transformer which has a split secondary. Parallel up the two secondary windings and wire one end in series with the primary in the correct phase. The impedance match will be about a 1-1/2 :1 step down. Being that the existing transformer has all it can do to handle the unbalanced DC in the secondary a 10Hy 300Ma filter reactor makes a suitable heising reactor. A 8 MFD 200VDC plastic film capacitor will work well to couple the audio from the topside of the secondary of the mod transformer to the junction of the 10Hy reactor and the modulated PA stage. Being that there is very little DC voltage that appears across the coupling capacitor a 200 volt rating is sufficient. This will allow the Valiant to be modulated in excess of 100% positive. Good luck,
Tim WA1HnyLR

The Tron has spoken. And many wise mods!!. There is an article from the old AM Window (button above) in tech write-ups that Tim explains clearly how to make sure the power transformer is wired properly to become a fabulous mod transformer. And checking the phasing in the transformer is important and also clearly explained.
I did  a turbo job on an Elmac AF-67 and it had 6550's as modulators. Backwards transformer to drive the mod tubes. Plenty of audio and soooo smooth.
But take your steps, one at a time, and get the beast working again, and then do the magic part.
Fred

Very wise words especially if one is a little rusty! 

Please get it working the way Dave had it first.  BTW....It sounded excellent on the air with his external audio amp driving it. 

Joe, W3GMS 

I'm hoping to find a loose connection in the grid circuit from the travels. We will see and thanks Tim for the Turbo recount. That may have to wait for a while. I want to get her back on her feet first and then gather some quality parts. I've read the TECH posting on how to, but I'll think on it first.
Thanks for the help.

Well friends I'm going to have to ask for some help if I can, I need someone in or around the florence Huntsville alabama area who would not mind giving me a hand on figuring out this Valiant.
Anybody up for it??
Thanks

I have that amp Dave used if you need it. It was a Crown DC300 he modified.

G

Thanks for the offer... First I have to get the rig running.. I never heard of a DC300.. I'll look it up.

Well after had tracing the curcits I have discovered that the Final and Mod. Bias curcuits have been disconnected and a replacement Mod,. Bias pot installed with added fixed resistors placed across the windings. None of this is complete nor connected to the ground side. This rig in it's current configuration could have worked, so this must of been a work in progress or is a dead carcus. The things some people will tell you just to sell something.
I've been looking for a replacement R61&62 pots for a month in the used market with no luck, the cheep $17-20 pots don't look like they would last under rag chew operations and unless I want to spend over $65 plus unbelivible shipping it looks like I'm going to have to do something else.
I've got an old Al-811 I'm thinking of converting to a modulator and feeding the that back into the finals.
I'm not sure but I susspect the Mod. trany. could not handle the 811's.
I know Tron has done this but I can't find a drawing of how he hooked it up and the component line up.
Anyone have such a document??

I knew Dave, K3ZRF(sk) most of my adult life and I worked him many times very close to his  passing with that rig.  I hear what your saying but it just makes no sense to me.  I  also know  the seller very well and he is an extremely honest man with lots of integrity.  My suggestion is if you have a bone to pick call him on the phone and discuss the issue rather than posting rants on this site. 
73,
Joe, W3GMS 

It was not a rant just a fact.. there were two of the Valiant II's and the one you most likely work him on belongs to another.

Sorry to say, but that was not the case.  The Valiant you have now was modulated with the Phase Linear amplifier so nothing inside the Valiant audio system was used including the bias pot.  Dave was a very competent engineer and really knew his stuff.  In the last year or so he commonly switched from your Valiant to a FT-1000D driving an external amplifier.  When the estate came up  everyone involved were Dave's good friends including who you purchased the Valiant from.  The other Valiant was more of a parts rig.  I saw them both and would of purchased them myself if I had not had several Valiants.   

Joe, W3GMS       

Alright we'll have it your way. At some point both bias pots were diconnected by cutting the return wire to the ground side of the circuit and seporated from a common connection. This leaves no bais voltage to either the modulators nor finals. I'm not accusing anyone of any intent. Just stating a fact as I do a hand over hand tracing of the circuits. The Mod bias pot has been replaced with a higher wattage pot of lower Resistance vlaue with added 2W resistors strapped across the ends to raise the value yet restrict the variance.
Thanks for your input..it's been so helpful

Joe, if no bias was used for the 6146's either the modulators or RF bias how did the 6146's function. I'm totally stumped on this. If the Fianl and Mod bias pots are not connected to ground on one end of the pots how in the world did Gary get this to function. I'm concerned to hook this back up the way the Valiant manual shows for fear of causing issue with what may very well be a perfectly fine design, I just don't know what it is.
Since W2VW has Gary's other Valiant II maybe he has some idea if the bias pots are connected and if he gets Grid Current.?

 
 
What I need is what is in the valiant folder he holds. It most likely would tell me the design.

The other Valiant reads grid current but I do not believe the reading to be accurate. The one here is only RF components. The modulator was totally external.

I've carefully checked the paperwork for anything that might help you.

The bias pot would not necessarily need to have one end connected to ground. A mod well known to many who strive for a good trap pattern is combine fixed and grid leak bias. The fixed bias should be just enough for cutoff. The rest of the bias is provided by grid leak and tracks plate voltage swing.

Not sure how this would function properly with a modulator though. 

I just can't figure out why a wire would be hanging out in space from the return ground on the RF Bias pot? I also do not know why it would not have grid current indicated. It does have fixed bais based on what you are saying due to the fixed resistance across the mod. bias pot. Not knowing what mods are done makes it hard to look for the missing grid current path. Or at least it does for this Amature. If anyone has any ideas where to look based on what mods are perceived to be in place let me know. My method of probing is not working.

I have Dave's valiant II working 100%. Finally got time to chase every wire down and connect everything the way I believe he intended it to work. Everything is solid into the dummy load no sagging current in either the Plate or grid on a 10min. shakedown. Audio works with plenty of swing.
It will go on the air tomorrow night as soon as I get the desk cleaned up and everything back in order. Then the fun begins setting the audio up for the ear on the other end.
P.S. It will remain out of the case...

Congratulations!!  Glad you stuck with tracing things out and getting the beast on the air.  Now its time to enjoy all your hard work.

73,
Joe, W3GMS

Congratulations!

Philip

I heard Jerry on the air yesterday morning and the transmitter sounded very good.  The audio was smooth and understandable even though the QRM was pretty bad.  Good work Jerry