RayTrack Horizon

[KD1SH]

  Anyone familiar with the RayTrack Horizon 6 meter amp? I'd never seen one before until I picked one up at Moxboro this last Saturday. A pair of 3-500Z's, glass chimneys and blower; external power supply.
  It's advertised as a 2KW DC input amp, but at 42 pounds the power supply seems a bit light, especially since it's a voltage-doubled supply. The blower looks a bit wimpy to provide Eimac spec airflow, too, but my Magnehelic will reveal the truth.
  A bit of work to do before it's ready for prime time: one of the panel meters is blown open, and the power supply has been hacked beyond recognition by a probably well meaning but ham-fisted hambone. Otherwise it's in pretty decent shape. Commercially built 3-500Z amps, I think, are a rare find.

[KL7OF]

Nice find... Looks like a Drake... When you get it out of the box, I'd enjoy seeing some pictures.  Good Luck.. Steve

[KD1SH]

Yes indeed, it does look sort of like a Drake, or maybe a Swan. I will take some pictures once I get it sitting up on the bench. I'm approaching this project with caution because I have a tendency to "project hop", and wind up getting none of them done. I've been working steadily on my home-brew 2X 4CX400 amp, and if I'm not careful I'll get distracted from that project and it'll be added to my long list of unfinished projects. It's my curse.

Nice find... Looks like a Drake... When you get it out of the box, I'd enjoy seeing some pictures.  Good Luck.. Steve

[Pete, WA2CWA]

Also made the DX-2000L:


 
A lot of appearance similarities to the Drake L4B.
Front panel says Columbus, Ohio. Maybe Raytrack owner is a former Drake employee.

Maybe the Raytrack 6 meter amplifier was their vision of the Drake L-6 that never made it to market.

Maybe all knowing Tom Vu knows; I heard him on 3885 this Tuesday evening along with a cast of characters.

[KD1SH]

  Looks pretty much identical to the 6 meter version. Power supply schematic is pretty much the same, too. Looking around the web, I don't see any information on other RayTrack products; I wonder if those two are all they made?
  Interesting observation on the power supply: The wire colors, as I mentioned, don't match the schematic, but the transformer primary windings are slightly different as well. See the attached crude drawing:
  Per the schematic, there are two identical but separate primaries. For 120V service you'd connect (via a terminal strip) both windings in parallel, and for 240V service you'd connect the two windings in series. The taps, at approximately 2/3, are switched in or out by a relay in the supply, controlled by the SSB/CW-Tune switch on the amp's front panel, effectively adding more turns to the primary and thus changing the turns ratio for lower voltage in the CW-Tune position or higher voltage in the SSB position. Not a novel idea—other amps use the same concept.
  Here's what's odd: looking at the picture, note that my actual transformer doesn't have the tap on the lower primary as in the schematic, but instead has a third winding—"F" and "G"—completely separate from the other two. My ohm meter shows that this separate winding is exactly equal to the "E" to "F" winding on the schematic version, and my testing shows that by connecting "E" to "G" in the "actual" drawing, the same effect will be achieved, changing the turns ratio and thus the HV secondary output.
  As I received it, someone had removed the relay and left the extra winding unused—wires just wrapped with electrical tape—and wired both primaries in parallel for 120V operation. I imagine his shack lights were flickering!
  What I'm wondering is, what would be the point, or advantage, of the transformer having that third primary winding, rather than the two tapped windings as in the schematic? I can't tell for certain, but that transformer looks very much like original factory part; it fits perfectly, there are no extra mounting holes, and it has the exact same dirt and "patina" as the rest of the supply. And the turns ratio works out to give the output voltage specified, too, so I doubt it's a retrofit.

Also made the DX-2000L:


 
A lot of appearance similarities to the Drake L4B.
Front panel says Columbus, Ohio. Maybe Raytrack owner is a former Drake employee.

Maybe the Raytrack 6 meter amplifier was their vision of the Drake L-6 that never made it to market.

Maybe all knowing Tom Vu knows; I heard him on 3885 this Tuesday evening along with a cast of characters.

[WA1LGQ]

I saw that amp in Marlboro just after Bill had bought it. It might have gone home with me if I saw it first. Yes indeed, Tom Vu might know something about it. I was listening to all the "abominations" as well Pete. Mr Vu made a rare appearance. Quite a crew.
 Bill, I am a project hopper also, especially with all the museum projects going on. Maybe see you for the next swapmeet on 9/9. The museum "excess items" tables will be pretty loaded this time.

[KD1SH]

Well, as you can see, the amp isn't quite ready for prime-time, but it was still a good find. God knows I need more projects!
And yes, you will see me on the 9th—love those "excess items" tables!

I saw that amp in Marlboro just after Bill had bought it. It might have gone home with me if I saw it first. Yes indeed, Tom Vu might know something about it. I was listening to all the "abominations" as well Pete. Mr Vu made a rare appearance. Quite a crew.
 Bill, I am a project hopper also, especially with all the museum projects going on. Maybe see you for the next swapmeet on 9/9. The museum "excess items" tables will be pretty loaded this time.

[KD1SH]

  Some pictures of the amp: The multi-function meter's coil was blown open, but I was able to remove the card from the bad one and install it into another 1 ma full-scale meter of similar shape, and it's now installed in the front panel.
  The 3-500Z's don't match: one's an Amperex and the other an Eimac. The anode terminal height is roughly the same, but note the larger glass envelope on the Amperex. A bit of a disappointment: the sockets aren't SK-410's, but ceramic types installed below the deck. Not terrible, but the real air-system sockets would provide better base and filament pin cooling.
  The chimneys are real Eimac SK-416's, but one has a slight crack running up the side. I wonder if there's some type of high-temperature glue that might prevent it from spreading?
  Overall it's pretty clean looking inside—no mouse carcasses, overt rust, or evidence of past zorches. The case will get a shot of paint, and probably the bezel around the front panel, too.
  I'll give those mismatched 3-500Z's a cautious try—after checking them for shorts or open filaments—just to verify that the amp is functional, and if it is, I might just replace them with new ones. One step at a time.

[KL7OF]

Thanks for the pictures of the guts... What is the coil made of?  looks alum strap but maybe tin plated copper?  I would certainly give those tubes a go.   sometimes mismatched works better than we think it might.  pretty clean machine!

[KD1SH]

  Some pictures of the innards of the power supply: Check out those boards. They appear to be home made—resist ink and etch—and the maker even put his call and date on them. One of the 25K 10 watt balancing resistors across the filter caps had run very hot and blackened the board. The caps all checked out on my analyzer. I also noted that several of the 470K resistors across the diodes in the rectifier string had increased in value to over 1 meg; one even to 1.6 meg. Like the caps, the diodes all checked out, at least on my multimeter.
  The guy had no bleeder resistor other than that provided by the balancing resistors across the caps, and there was no series resistor on the B+ to limit damage in the case of an internal arc in a tube, although both are present in the original schematic. I'll be including both in my rebuild, as well as restoring the SSB/CW-Tune switch functionality, and probably giving it a soft-start, too.
  

[KD1SH]

It's aluminum strap; heavy gauge, like 1/8" thick and about 1/2" wide.
Interesting tidbits: notice that, on the front panel, the markings for the load knob include a red arrow pointing in the clockwise direction with the legend "increase". Normally, increasing the loading implies decreasing the capacitance—un-meshing the plates—but neither the capacitor nor the shaft has a mechanical stop, so whether you're increasing or decreasing the loading depends on where you are in its 360 degree rotation.

Thanks for the pictures of the guts... What is the coil made of?  looks alum strap but maybe tin plated copper?  I would certainly give those tubes a go.   sometimes mismatched works better than we think it might.  pretty clean machine!

[KD6VXI]

Having a bleeder be the balancing resistors is fine, just size them appropriately, realizing most metal film are 300 volt devices.  I stopped using bleeders decades ago when I moved to electrolytics.

Dump equalizing resistors and any caps across the diodes.  Use 6A10 or 10A10.  You can't burn them up.

Fuse of a piece of braid single strand on two stand offs.

Make sure you leave enough space to ensure breathing room for the resistors dissipating some heat!

Cool looking amp, for sure.

--Shane
WP2ASS / ex KD6VXI

[KD1SH]

 10A10's are great; I've got a bunch of them, but in this case I used 1N5408's—3 amps and 1KV—because I'm mounting the string on a glass turret board and the lead thickness of the 10A10's made them a bear to wrap around the turrets. I've got a much bigger supply that I'm also working on, for use in another HB build (a 3-500Z three-holer), with a transformer weighing around 80 pounds, and that one is definitely getting 10A10'a.
  I did put caps and equalizing resistors across the 1N5408's, but yes, I agree; the modern school of thought seems to be moving away from their use, largely because modern production techniques produce more consistent diodes. Well, it's an old habit, and I had plenty of caps and resistors.
  I may just skip the bleeders and let the balancers do the job, like you say. I always figured that bleeders aren't entirely for the obvious safety reasons, but they're also a legacy from the days when most power supplies had gonzo-henry choke filters, where maintaining a minimum load improved regulation a lot more than with capacitor filters.
  The supply has a perforated cover, but I'm going to see if I can kluge a small fan in there.

Having a bleeder be the balancing resistors is fine, just size them appropriately, realizing most metal film are 300 volt devices.  I stopped using bleeders decades ago when I moved to electrolytics.

Dump equalizing resistors and any caps across the diodes.  Use 6A10 or 10A10.  You can't burn them up.

Fuse of a piece of braid single strand on two stand offs.

Make sure you leave enough space to ensure breathing room for the resistors dissipating some heat!

Cool looking amp, for sure.

--Shane
WP2ASS / ex KD6VXI

[KD1SH]

  Okay, I stripped out all the of original parts (I use "original" with discretion; I think much of it was home-brew rather than factory), cleaned it all up, and put my own HB parts in their place.
  I consolidated the filter functionality onto one board—the original divided up the filter caps between two boards—leaving me with a vacant space for my relay/control board, which reinstates the SSB/Tune function which was missing on the "original", and adds a soft-start; one relay for each function. The soft-start delay is provided by the ICM-102 module, the little blue box on the relay board. The two 10 watt resistors above the relay provide the minimum load which the ICM-102 requires to hold the relay closed.
  The ICM-102 is a neat little unit, but I was disappointed in its adjustment resolution—I've got it set for 3 seconds, but turning the knob just barely a degree further gives me about a full minute.
  Those two gold anodized resistors are 12 ohm 100 watt, for the soft start, one in each leg of the 240v and bypassed after 3 seconds. The little cylindrical gizmo mounted in the panel is a combination red light and buzzer, which illuminates/buzzes during the 3 seconds the soft-start relay is open, giving me warning should the relay ever open up after that. Those 100 watt resistors are beefy, and heat-sunk to the chassis, but they wouldn't be long for this world if I pulled full transmit current through them. When I tested the circuit I used two 200 watt light bulbs in series across the 240v output, and watched them start off dim and then brighten when the relays closed after 3 seconds.
  The original had two push-button circuit breakers—one for each 240V leg—but I replaced them with fuse-holders because they were 20A breakers, which I felt was excessive and provided minimal protection at 240V; I suspect the intent was to make them suitable for 120V input, which I have no intention of ever using.
  My bleeder/equalizing resistors on the filter board, across each cap, are 47K 5 watt, and my figuring indicates that they should be dissipating 2 watts each. I can smell them getting warm in operation; I may install a fan on the bottom cover, but the filter board is mounted vertically, forming a convenient convection chimney in the space between the board and the metal housing, so it'll probably be fine as is. I'll give it a burn in test, and maybe shoot the resistors with my IR thermometer to see how things go.
  Now, on to the amp itself, which really doesn't need much.

[KD1SH]

More pictures: