The AM Forum

Trying to bring back alive a much neglected HX-50A.  On the schematic, C174 and C175 are shown as 40 MFD 600 V caps in series with 40K, 5W equalizing resistors across them.  The parts list, however, calls out these capacitors as 90 MFD 500V each.  The actual cans are labeled 90MFD/500V.  Would I be correct in assuming that the schematic is wrong?  Please note the schematic is for the original HX-50 with the 5R4 rectifier.  The '50A has a bank of diodes under the chassis, and a hole where the rectifier tube and its socket were on the original version.

Digi-Key has 82 or 100 MFD caps available at the 500V rating.  In the series configuration, would I be better off going slightly low (41MFD) or slightly high (50MFD), assuming the design goal was for 45MFD of capacitance at 1000V?  I'm thinking it probably isn't that critical.

Anyone have experience with this transmitter?

You are correct in assuming the error between the diagram and the parts list and the caps are not all that critical...

Either value will work, but I personally would go on the high side.

You might also increase the size of the 40k resistors to 100k to reduce the heat generated there. Works fine that way...

The HX-50 was a good little xmitter. Have fun with it...
 

You're right, it's not that critical.  Use whatever you can obtain that is reasonably close.  Just don't exceed the voltage rating on those type of caps.

Fred

I also have an HX-50, but not the A model.  The bandswitch has a position for 160, but I do not believe that option was installed in mine.  Does your later schematic show the details for the 160M conversion?  If so, I would appreciate seeing it.  My plan is to set the HX-50 up with the HXL-1 Hammurlund Linear along with using the HQ170 as the receiver. 

Thanks!
Joe

Thanks Ralph, Fred, and Joe!  Caps have been ordered.  Joe, the supplemental instructions for the HX-50"A" only note that 160 meters is optional.  I believe they had a parts kit available.  It would be interesting to hear from anyone who has this mod. 
Jim

I think your right about the kit.  I did see the extra xtal for 160M operation on your posted schematic but I am sure some extra coils both for the driver stage and final were included as part of the kit along with some likely padding on the loading cap.  Yes, any kit owners out there?  It sure would be good to get some documentation to make the conversion a bit easier.   I could figure it out, but why reinvent the wheel!! 

Good luck with yours. 

Joe-GMS 

I would suggest getting the correct schematic and parts list for the HX-50A. Using the HX-50 schematic is probably a recipe for confusion and hair pulling. If you had the correct schematic and parts list, the correct values for all power supply components would be clear plus the fact that the power supply between the two models is different. Also the HX-50A has three relays and the HX-50 has only two (per the schematic). There are also numerous wiring and component differences between the two models.

I think the HX-50 was a work in process the entire time is was in production. Hammarlund issued a number of service bulletins, changes, corrections against it, but as far as I can tell, never reissued the initial schematic. So, out in the real world, there are probably "X" number of HX-50's that were not identical in design and wiring.

The 160 mod kit for the HX-50 and HX-50A consisted of 5 capacitors, 1 choke, 3 coils, 1 crystal and wiring. If you look carefully at either the HX-50 or HX-50A schematics, the 160 mod additions are outlined in dashed  areas.

Pete, you are correct.  I had to put on my extra strength reading glasses.  Coils T1001, T1002, and T1003 are on the schematic, but not on the parts list for either the 50 or the 50A.  The supplemental instructions for the HX-50A (to be used in conjunction with the book for the plain vanilla HX-50 say it is "... an advanced version of the HX-50 unit. The HX-50A differs from the  HX-50 as follows:"
Then they itemize:
1. ZBZ (Zero Beat Zero) function standard, not an option
2. Adjustment of calibrate level via front panel control
3. Improved VOX circuitry for more optimum CW-VOX as well as VOCE-VOX
4. Increased output power to 200 watts PEP input for SSB.

There is also a Bulletin outlining 9 component changes including the addition of a second OA2 VR tube.

Definitely a work in progress.  I would love to know how many of these were produced.

Jim

Sounds like we need to do some business off-line Pete.  I need to see what I have as far as documentation and then we can talk.

Joe GMS 

The supplemental instructions consisted of 12 pages including the HX-50A schematic which was added to the front of a HX-50 manual. I don't believe they ever printed an actual HX-50A manual or at least I've never seen one.

1 & 2 were useful; with 3 they diddled with this several times in the HX-50 with bulletins; with 4, mostly sales BS, use PEP to inflate power output number over what was printed in the original HX-50 manual.

What they don't tell you in this info is all the circuit and component changes they made in the HX-50A. That's why it's important to at least have the HX-50A schematic.

The HX-50A was around from 1965 to about 1968. That one page bulletin with the 9 changes on it I think was dated sometime in mid 67. Other then the schematic that came with the 12 page supplement, I don't recall ever seeing any updated schematic.

The parts list wouldn't show any of the parts for the 160 mod. The mod was order-able as a "factory install" option, Part No. PL26860-G1, or as a field installation option, Part No. PL26860-G2. The installation and alignment instructions was an 8 page document.

Pete,
 
Does any of the schematics show the schematic symbols for the additional components for the 160M mod?  I realize no values on the parts list, but maybe a schematic showing the added components.  Also, I wonder what documentation came with the field install option.  Have you ever seen that documentation that possible came with the field option? 

Thanks,
Joe - GMS

Both the HX-50 and HX-50A schematics show the added components and wiring for the 160 mod with dashed lines and/or dashed boxes. Unfortunately, there are no inductance values specified for the driver and two mixer coils so those would have to be determined the old fashioned way. I have the installation and alignment instructions (Part No. PL26860-G1/G2).

My internet searches have so far failed to turn up a schematic specific to the HX-50A.

Thought I'd share a couple of pictures of my transmitter in "as received"  condition.  At least the previous owner wasn't a smoker. 

After a couple of hours with vacuum attachments, rags, and q-tips, "she cleaned up pretty good!"

Thanks Pete.  I need to see what I have and don't have, but I don't think I have anything on it.  Mine came from Joe-N3IBX and looks in nice shape.  Once I determine what I need I will get in contact with you via the normal channel. 

Joe-GMS   

Did you intend for these pics be a "before" and "after?"   They seem to be identical

Oops, they are identical.  Still trying to figure out the *^$#* "photo" app on my new Win 8.1 box.  Should have a couple more to share later today or tomorrow.

Jim

Download this application;

http://www.ghisler.com/whatsnew.htm (http://www.ghisler.com/whatsnew.htm)

Called "Total Commander" It's sortof freeware with a minor nag screen (pick a number: 1, 2, 3)  After you get by the nag screen it's a fully functional file manager with two screens.  Most times you can just use one screen or you can use the two screens: one as source the other as destination for copy or move functions. It's styled after the old Norton Commander of the old DOS days (remember DOS ye old farts?).  It also has a FTP function for the advanced users that I have used to upload to some of my web sites.  Works very well.

We used it at Raytheon and another company we did a lot of business with "NearField Systems" used it.  Works great.  There you should see the two file names clearly.  Oh yeah, it can come in many different languages for our friends across the pond.

Al

PS: You might want to go to the home page too.  Also, there is a screen shot page to show its functionality

http://www.ghisler.com/screenshots/en/ (http://www.ghisler.com/screenshots/en/)

Thanks Al, I'll check it out!
Jim

Well, you did say, "Thought I'd share a couple of pictures of my transmitter in "as received"  condition."
And you did.

Time to post an update.  As they say in the country music scene, "she cleans up real good!"  Under all the dirt, dust, and lint was a nearly unblemished finish.  Under the deck, new filter caps are on terminal strips attached to the "Z" shaped partition.  Power was applied yesterday using a Variac to bring it up gradually.  No arcs, sparks, or drama at all.  Testing and evaluation are next.

now THATS a before-and-after .... good work

Update:  I've had my HX-50A on the air.  AM performance got good comments on the Midwest Classic net Saturday morning, and have checked in to the Vintage SSB net also.  I'm still working to get an issue resolved: the "Zero Beat Zero" function worked when I first checked out the rig, but stopped working somewhere along the line.  I still haven't been able to get a schematic specific to the "A".  BAMA offers the supplemental instructions for the A version, but no schematic. I've done Google searches but keep coming up with zilch.  Anyone out there have one?
Jim