Valiant II - Val- I - Ain't Q: heat & hum??

[WBear2GCR]

Ok, long story short.
Dave Goncalves, W1EUJ picked up the BC-610E today with a trade that brought me a Valiant II.

The Valiant has been "hotrodded" by I think Dave, KA1something or other - who sold his stuff because of a divorce according to Goncalves??

So, it was wierd on 80m. Wouldn't produce drive from the VFO. Had it boots up on the bench. Turns out (two hours later or more) that the stupid "kicker" switch on the bottom of the VFO was being kicked one detent too soon, so it kicked on 80m instead of 40m. Drove me nutz looking for it, got a good tour of the bottom end of the unit. It worked fine using the xtals, but not the VFO!
Heh heh.

Ok so got that fixed.

Now the two main problems are:
- It gets friggin HOT! The chassis gets hot, that front panel drive pot gets hot, the stupid bias pots on the side get hot. (suppose a fan will work, just wondering if they all run hot)
- Hum. The audio has nice hum. Both in Spot, CW and more in AM with outwithout modulation.

Oh, the power supply is solid stated. Looks like stock config (choke input on B+ and cap intput on low B+). I was going to hang some extra caps on the B+ rails, but I ran out of time and decided to ask here first

Secondary issue is that this is a hotrodded speach amp and sweep tube modulators. Looks like sort of a K1DEU mod, there's some documentation, and it shows several variations. There's a 6L6 driving the sweep tubes it looks like (what for, I dunno). The gain is a bit lacking, but ok if you turn it all the way up (doesn't effect the hum) AND the "clipper" control is there, and wired, and looks replaced but has no apparent effect! (I monitored it using a DUMMY LOAD and my R-388...)

Well, another rig - NOT ON THE AIR! 

Any info, suggestions, knowledge of this rig and/or this unit in particular is appreciated!

[w3jn]

Rip the audio out by the roots and install a line to grid xformer for the mudulator toobs, run yer line audio right in to that.  That's what I did on my Valiant II - no hum, no audio issues at all 

[WBear2GCR]

Nah nah nah!

I can bring out the primary of the driver transformer for external drive...
it's not a stock unit. It's a replacement with more HEFT.  Probably one of the Hammonds or one like it.

I'll leave the guts, preferably make it work.

The HUmmmmmm is also on the CW carrier. Gotta clear that up foist.
It is possible just the filter caps are flat.

When you tune yours up, and the plate is not in resonance, does it slam the meter hard to the pin until you get it dipped? This one does. Most disconcerting!

                           _-_-bear

[The Slab Bacon]

Bear,
         Whenever you hear me running at the 100w power level, I am using a Valiant II. I personally love mine, it has been a real workhorse and an apliance since I rebuilt it years ago. The drive pots and biass pots are supposed to get a little warm, they are directly accross their respective powa supplies. However if you "solid state" the powa supplies, you should add some extra resistance at the "hot" side of these pots to keep their dissipation levels somewhere where they were designed to run. Mine has never been solid stated.

There are more mods out there for Valiants than recipes for grandpa's secret BBQ sauce. The trick is to find the ones that work for you. I have found that they are pretty easy to make sound good with pretty simple mods. what I usually do to them is pretty easy.

1. Bypass or just remove the speech clipper circuit.
2. Fatten up the audio coupling caps.
3. Swap a pair of 6146Bs fo the modders, and readjust their biass accordingly.
4. Wrap a little global feedback around the audio section (if you desire,but not necessary)
5. Load the finals for 275-300Ma @100-105w output instead of the 360Ma called for by
    the  manual. this makes a big difference by helping to relieve some of the saturation
    of the already undersized mod transfoma. And no one is going to see any difference in  
    their S meter for the 30-40w difference in output as it is well less than 3db. But they will
    hear the difference in your audio.
6. you can also change all of the bypass caps on the plate HV supply line (all 5 of them)
    from the original .01s to .001s.

Try it......................................youl like it!!
                                  
                                                                           the Slab Bacon

[The Slab Bacon]

When you tune yours up, and the plate is not in resonance, does it slam the meter hard to the pin until you get it dipped? This one does. Most disconcerting!
                           _-_-bear

This is a good thing!! It means you got good final tubes and plenty of drive!! dont forget that with only 650v on the plates, it was designed to pull lots of current.

[WBear2GCR]

Frank,

Good mods. But this unit has NOTHING stock in the speech amp other than the mod iron! Sweep toobes in the thing!! Different toobes before that. 6L6 driving the things, or else it's a screen regulator - dunno yet, but it is next to the Sweep toobs.

I think that that caps shunting the HV line have been changed.

It is already soylent stated PS. Plug in rectofryers for the HV, looks like a string-o-diodes sitting in there for the LV.

Maybe it has the "three diode" negative peak limiter. Yet to get that far into it.

WIERDEST envelope pattern when I look at it on the scope I have EVER seen!
The thing modulates so much that the carrier seems to wrap up and down with the modulation! Oh, it seems to be asymetrical, major more positive peaks than negative.
Doesn't sound bad at all on the receiver, other than the hum...

Otoh, the plate meter seems to not bounce up at all on mod peaks, actually it does not much of anything, if anything it dips slightly, which could just be PS voltage dip.
Ought to watch the PS line ammeter on peaks.

And yeah I loaded it up to ~300ma.
The plates seem to look a little bitty red...

So far just on the Dummy Load.

Good point on the whyare wound poots.

          _-_-bear

PS. oh I tried my "stock" D-104 head on the unamplified base that I got with the Val-I-Ain't? Pure crap. Sounds like everything below 3.5kc drops like a stone! Hee hee. Maybe the front end of this "mod" doesn't have the requisite high impedance inpoot! The ceramic element that came with it sounds ok, fine.

[The Slab Bacon]

If the plates of the finals are showing some color at that current level, something is a little out of kilter. Mine finals run cool as a cucumber at 275-300Ma. Either your static biass is not right. (Valiants use both fixed biass and a small amount of leaky grid as well) Or your shunt resistor is out of wack and the meter is reading a little low.

Also whoever modded it may have set it up to force-feed it some processed audio. This is not uncommon and would explain the lack of gain, and the assymetrical modulation. Also if it was set up for a higher level inpoot and you have the gain turned up high enuff for a bare mike to work, that would kinda explain why it iz pickin up some hum.

                                               The Slab Bacon

[W1EUJ]

The guy who modified the rig is Dave, KE1AV. He is a member of this forum, perhaps you can PM him for some more info on his mods.

The significant modification without well written documentation on it was part of the reason I let it go.

Dave Goncalves
W1EUJ

P.S. Thanks for the stack of tuning cards. I think I have enough for three 610Es!

[Steve - WB3HUZ]

If the plates of the finals are showing some color at that current level, something is a little out of kilter.

Those 6146s aren't like 4-400s or other big tubes that are designed such that their plates are supposed to glow in normal operation. Glowing plates on 6146s is usually bad, although, they are pretty tough and can take some abuse.

[WD8BIL]

Glowing plates in 6146's usually means; bad/no biass setting (as the Slab mentioned) or unwanted oscillations.
 
Happy hunting.

[WA1GFZ]

Or you are running PDM at 1550 volts peak.
My PDM V2 eats 6146s about every 4 years.

[WBear2GCR]

Yeah... all good points.
One of the 6146Bees is just showing a little red... I'll have to swap it out and/or check the bi-ass voltages. No sign of parasitic on the scope - but it may be missing it if it is up in high VHF.

At first I thought one was SHORTED, because the plate meter WENT THWANG onto the pin when I keyed it up! So I took one out and ran two, and it didn't go THWANG onto the pin anymore, so I dipptdit, andit was happy. Then I poot the thoidwon in andit was ok after a good deeping.

The audio circuit is a 12AX7 of unkown config at present, into a 6L6, into a pair of bigarse sweeptoobs. The stock input jacks are stripped off the back and a 4 pin is subsituted for the stock. PTT has been installed in the unit I think, but I think it keys the B+ like the original.

I'll fight through it, I guess I have to now.
Probably I will try for a quick HUM fix with extra caps (the hum is present with mic level OFF), and if that does not fly, then I will build my own speach amp circuit for the Viker, and if that works as anticipated, I'll change of the Val-I-Ain't circus for that one. :_)

I might set it up to just dump heavy negative biarse onto the grids and have the PTT relay jump it back to regular operating levels... not sure if that is a good idea, but seems better than jacking the B+ on everytime. Opinions?

The modulation seems wildly heavy somehow, not sure what exactly is going on yet, as it seems to "pick up" the carrier's trace of on my scope! Not just neatly modulate it. Having never run a rig that can 'super modulate' I am not sure if this is what it should look like or not? Any answers on that? (it sounds good tho')

super buzy this week, and weekend, so looks like next weekend before I get on to them again... grrrrr...

thanks Dave for the callsign info, I'll PM/email him!

           _-_-bear

[WBear2GCR]

Ok!

All good now!

It's (as some know) ON THE AIR!!

Turns out that a combination of user error and prior owner error was responsible for both the wierd carrier effects on modulation and at the same time the slight glow in the plate(s)! What could that be?

Well, the SSB connector and the RF OUT connector were mislabeled!
Should have noticed that by inspection, but no...
That meant that the dummy load connected to the rig had zero effect at all. Great.
Figured that out, and relabled the thangs, and guess what? It works ok fine!

Had to resolder a cap in the speech amp... traced the thing out. 12AX7 in cascade driving a 6L6 whose plate is connected to a Stancor A-3845 (whatever that specs at) into a pair of 6DQ6, with a 3 diode negative peak limiter, 700vdc on the plates.

Overall a success, finally! 

                  _-_-bear

[WBear2GCR]

Right Mack!

I found i had downloaded a 1959 Stancor cat on my confuser... saw the same thing.
It's being run backwards, of course. Single-ended 6L6 driving the secondary (I presume) and the primary being P-P running the gridz.

              _-_-bear

[W1EUJ]

I am very glad this VVII is in the active and competent hands of the Bear! I had it for a couple of years as I lived in a location where a transmitting antenna was not an option. Now that I'm the proud owner of a new home, with land and seperation from neighbors, I hope to work you on the VVII in the near future. I'll likely be on a DX-60 and linear. (Why did I give up a nice working radio for a unknown-condx rusty one?  - I like big tubes, and i like them rouuuuund.)

As for the BC-610, I have been collecting a number of parts to replace those missing - coils, TUs, that conical heater on the modulator deck (those are a wild sight to see running!). I just found a fellow out west that has an entire RF deck to replace the rusted out one (you saw - the rust actually applied enough pressure to pop the spot welds on the right side!). At this moment, it sits in the garage as a work of art, that I come to see every night to enjoy the sight of it. I think it was a very good deal!


David Goncalves
W1EUJ

[WA1GFZ]

You want to eliminate a large source of heat solid state all the supplies. Just take tube bases and wire in diode strings. The plate voltage  will love you. My V2-CDC is at 760 VDC. My Line is about 126 so need to put the 5 volt winding in series with the primary of the lv transformer. heaters are at 6.7 VAC

[WBear2GCR]

Please note the earlier posts, this Val-I-Ant Duece is already solid state modded.


        _-_-bear

[WA1GFZ]

V2 CDC I added a large filter cap on the plate voltage coming into the Audio amplifier area and killed a lot of hum. It may have been 100 uf 450 v cap. I have not mounted it yet but looking at the chassis side wall behind the driver transformer. I also added a 100 uf 450 volter beside the final sockets terminated to the terminal strip that feeds the two RF driver stages.

[WBear2GCR]

Ya, there is extra in this one too... not sure if it quite that much, but substantially more than stock... charging the extra cap can cause extra heat though, as the xfmr works harder to keep the caps charged.

                           _-_-bear

[WA1GFZ]

load is the same so extra current increase is not that great just reduces ripple..You could change to choke input filter if you are worried

[WBear2GCR]

no worries mate!