EF Johnson Being Acquired... By JVC Kenwood

[NQ6U]

Most Valiants sounded the same no matter what the power.

[kb2vxa]

"The worst was the desk kilowatt driven by the preferred Ranger, second choice the Valiant." The DESK KILOWATT is what I'm talking about, an AM final, not a linear amplifier, that operates at either 1KW or 500W input driven by the matching Ranger. The Valiant CAN drive the kilowatt BUT only with the RF drive and audio gain reduced and closely monitored because drive to the KW becomes unstable. I'm at a loss how a Valiant can operate at half power, or why someone would attempt it.

I'm glad I constantly entertain you, even if it is because you have some sort of reading difficulty. Since a picture is easier to understand, here's the desk with the Ranger used as an audio and RF driver.

[w2amr]

Most Valiants sounded the same no matter what the power.

There's the Valiant, here's the Ranger

[kb2vxa]

My God, it's full of Yogis!

[w2amr]

"The worst was the desk kilowatt driven by the preferred Ranger, second choice the Valiant." The DESK KILOWATT is what I'm talking about, an AM final, not a linear amplifier, that operates at either 1KW or 500W input driven by the matching Ranger. The Valiant CAN drive the kilowatt BUT only with the RF drive and audio gain reduced and closely monitored because drive to the KW becomes unstable. I'm at a loss how a Valiant can operate at half power, or why someone would attempt it.

I'm glad I constantly entertain you, even if it is because you have some sort of reading difficulty. Since a picture is easier to understand, here's the desk with the Ranger used as an audio and RF driver.

I know what a desk KW is. And, I've had several Rangers over the years. Thanks for playing.

[n2ize]

Their ham transmitters with the exception of the Viking 1 & 2 left something to be desired, power supplies and modulation transformers, they skimped on both. The worst was the desk kilowatt driven by the preferred Ranger, second choice the Valiant. At half power it sounded fine but at full AM output the power supply flagged and it sounded like mud. Now it's commercial two way FM gear, not all that popular.

I have heard some awesome sounding Valiants running at full tilt. I wasn't too crazy about the pair of 6146's as modulators. I was thinking of replacing them with a pair of triode connected 807's or a pair of 811's. Might still do it if I ever get back to working on the Valiant. it was problematic on its own but otherwise a nice rig. The ranger itself was a pretty nice rig as well, I have heard a lot of beautiful sounding rangers out there. I never had a Desk Killowatt but I knew a few people who had the Johnson 500 which ran a 4-400 in the final. Modulated by a pair of 572B's in place of the 811's and a few minor mods to the speech amp/driver or bypassing the speech amp and pumping in a nice clean audio signal they sound pretty darned good. I own a Globe King 500 with a 4-400 in the RF deck and 811A's in the modulator deck. The stock RF deck is a bit flimsy and tends to zorch over now and then. I put a heavy duty inductor in mine and beefed up the variable caps. I should try modulating it with a pair of 572B's. I forget off hand if the 572B is a triode or a tetrode but in any event they could be triode connected.

[kb2vxa]

Few plate modulated transmitters sound good at less than full rated input because it raises the P-P modulator load impedance above the proper value. I'm not too happy with 6146s as modulators either, while they may be used they're not made for audio, 807s are but they have a different P-P rated impedance and don't make a good substitute in the Valiant. What I really don't like about the V is the 3 6146s parallel in the final which gives too low an RF output transformation ratio for good harmonic and spurious signal suppression. That's why the Apache and DX-100 having two give a cleaner output.

Globe had its problems because in an effort to keep price down while still turning reasonable profit Leo Meyerson used surplus parts and tended to skimp on ratings. I forgot which CW/AM transmitter a friend had, something in the 150W range, the surplus final and modulator tubes were cheap and plentiful when the rig was built but when he acquired it in the 70s they were made of unobtanium. He had to search far and wide to find them, at a very high price he had them shipped from England. When we got it whipped into shape it sounded great, none of that yellowy telephonium sound with a good mic on it. What I liked best was the built in modulation peak limiter. When the mod gain and mic gain were balanced out it held 100% without pumping or breathing. The unanswered question however is what to do when those tubes need replacement and the supply in England runs out, he sold it.

Oh, the 527B is a high-mu power triode for use in Class AB2, Class B, Class C RF, and audio amplifiers. I'd stick with the 811As, the 527Bs won't buy you any improvement as modulators. They have 300% the plate dissipation rating so unless you piss beat them in RF service like knocking the slats out of a Collins 30-L1 with high SWR even there the stock 811s will do. Oh, a fried 811 out of that Collins amp makes a neat tree topper for Ham Christmas too and the tree got it's picture taken for the QST December 99 issue. <gloat> <brag> <snicker>

[w2amr]

I have heard some awesome sounding Valiants running at full tilt. I wasn't too crazy about the pair of 6146's as modulators. I was thinking of replacing them with a pair of triode connected 807's or a pair of 811's. Might still do it if I ever get back to working on the Valiant. it was problematic on its own but otherwise a nice rig. The ranger itself was a pretty nice rig as well, I have heard a lot of beautiful sounding rangers out there. I never had a Desk Killowatt but I knew a few people who had the Johnson 500 which ran a 4-400 in the final. Modulated by a pair of 572B's in place of the 811's and a few minor mods to the speech amp/driver or bypassing the speech amp and pumping in a nice clean audio signal they sound pretty darned good. I own a Globe King 500 with a 4-400 in the RF deck and 811A's in the modulator deck. The stock RF deck is a bit flimsy and tends to zorch over now and then. I put a heavy duty inductor in mine and beefed up the variable caps. I should try modulating it with a pair of 572B's. I forget off hand if the 572B is a triode or a tetrode but in any event they could be triode connected.

I tried a pair of 572B's in place of the 811's in my 500 once, and really didn't notice any difference.