The AM Forum

Hello my friends
I am trying to get the low power station up and wanted to use an HO10 I musta gotten on e-bay at one time.
It powers up but the trace is not too bright and I can't focus the trace. No scheezo. I'm sure they're around the Internet for free. Would it be just electrolytics or is the CRT dead. The HO10 is a perfect size for the operating position.
I have another BIG scope, but that would take up the entire table.
Is my HO10 worth digging into, or start searching again?

Thanks again.........Been busy the last few days with family visiting for a Christening and today was chemo day............ONE more treatment  :-\

Fred

Mop, can you measure the HV?  If so is it ok?  Do you have the manual?  Do voltage checks on the PS.  Hope the CRT is ok.

Shitcan it and get a decent Tektronix at the next hamfest.

The fixed resistors that hang off both arms of the focus pot most likely have to be changed. Over time they increase in value; they really should be 1 watt resistors rather than the 1/2 watt they put in. Bad resistors here will screw up the focus adjustment and intensity. Check and/or replace the .15 mfd capacitors in the HV power supply. They go bad, leak, cause a mess, and smell. Actually you should also check all the resistors in the HV section to make sure they haven't changed value a lot. As Jim says, check the voltages. HO-10's and HO-13's look cool. However, most HO-10's will show a slight AC ripple on the horizontal line. Transformer and CRT locations are the common cause. Most of us live with it.

Edit 6/29 - I deleted the picture - takes tooooooo long to load

Before you go digging too deep into the unit checking resistors and caps, always check the easy stuff, which is also usually the prime offenders: tubes.  I had two HO-10s, and one had the very symptoms yours has.  It was a bad rectifier tube.

Thanks to all,
And Pete I remember those HO train sets. I still like the older Lionel 3 track size.

I bought a CD from epay that has a lot of Heath scheezos and the HO10 on the way, but I'll do the simple things first. In the meantime I'll put the BIG scope under the Froggy 7700 and enjoy the big bright display. You gotta look hard at the display in the HO10! I'm spoiled, I guess. The HO10 would fit nice on top of the Rx. Oh Well!
Thanks
Fred

Fred:
This should get you started. Print it and start your trouble-shooting:

Hey Pete
You're the Man!!
Thank you.
The scheezo tells the whole story.

fred

The HO-10 by its inherent design has a crappy  display, mainly  due to 60~ hum pickup from several sources.  I modified mine and it works very well.  One thing I did was to throw away that useless piece of tin that poses as a magnetic shield, wrapped around the neck of the CRT, and replace it with a real CRT magnetic shield salvaged from some old military surplus scope.  I also re-routed the filament line and added more filtering to the HV power supply.  I  recall installing an astigmatism adjustment to allow me to focus the image more sharply.

The original display was modulated by 60~ in the vertical position of the trace as well as the brightness of the trace, and would not completely focus.  The Heapshit assembly manual says something to the effect that "some hum in the trace is normal, but should not limit the usefulness of the scope as used for modulation monitoring."

I have the documentation of my mods somewhere, and will publish them if I can find my notes.

Phred
          Pete is right, I have 2 ho ho 10's and 1 sb-10. I have had the same problems with all 3. the resistors in the HV lines to the fockus potz and intensity potz go up way high in value. They were not designed to handle the high voltages that they carry. Replace thoze resistorz with something more robust and you will be ok-fine.
Also check the HV rectumfryer tube socket for dirty / loose pins allowing the filament
to go out. I had to replace thoze resistorz in all 3 of mine.
                                                                                 the Slab Bacon

Honest to god, why mess with these miserable things?  For the amount of time you hafta spend to get a halfway usable result you could drive to a hamfest, buy a $10 scope, drive back, and hook it up.

John
you said it all ! It would just be nice to have something small in the space I have for the HO-10 scope. I have a big Beckman scope on the table and the Yaeseu frg 7700 sitting on top. I like the big bright display. I'll play with the Heath scope and see if I can improve on the wimpy display I see now. I have the time. Just need to have a better days health wise. The Chemo really wapps me somedays and I don't feel like doing S#@^. I start feeling better around 7PM    :'(
Fred

Fred, I have a little B&K 5 MHz scope that's no bigger than a hoho-10, you can have it if you want.  The picture tube is a bit dim but works fine business otherwise.

OK John
Thanks for the offer I'm good in QRZ. I'll pay for shipping.
Fred

Cuz some hams like to tinker.

Fred, no problem at all, gimme a few days to pack it up.  Don't worry about shipping.  It's a karma thing.... the next piece of unobtanium I need will most likely fall into my lap via the generosity of one of the other forum members when I do this  ;D

73 John

Very true!  But sometimes, you can't polish a turd  ;D

Fred, maybe you should send JN a turd to polish for practice.

Now cum on guys.......Im sure JN is a nice guy......he just dances to a different drummer than us "regular" hams.. ::)

I, like many, have my bi-assed opinions and am not afraid to share 'em  ;D

As far as me being a nice guy, well.... that's debatable.

John,
Like it or not........u ARE a nice guy.....not to mention always very helpful. 8)

Very much so!!!

Got to put my boots on!

(http://www.partypants.co.uk/images/retro-60s-70s-boots-fur-purple.jpg)

Be careful Pete, out here people also die with them on.

I prefer this place over another because the people are so much more civil to each other and have humor sprinkled throughout rather than trashing each other.

I don't know if you have noticed but on QRZ they have a system with little yellow and red squares.  When a member crosses a line, they get one square.  On the fourth square it is yellow and red, the fifth is red and one more baddie and they are banned.

You only see them in the Rag Chew section where people really vent towards each other.  Here that forum was moved to another board.  In my estimation, that was a wise move because the fog is gone.  I also notice some of the people who were here are no longer present.

This is a good board with helpful, knowledgable people and a very useful resource.  You among them.

Hey John
Thanks. I'll look fer it one day to mysteriously show up at MOP radio.
I have done the same thing for other Hams. I have heard QSO's where some guy has a need and I have looked up the call on QRZ and sent what he was looking for, just for the hell of it. Usually it's small pain in the ass things that aren't worth going to
e-pay for or Shadio Rack doesn't carry anymore. I'll get a happy QSL card back and sometimes they'll send a check to cover the postage. The Ham op is usually shocked that someone was just listening out there in the aether.
G'day
Fred

ahh shit fred I forgot all about this.  Sorry man I'll pack it up and send 'er on its way to ya.

Got me one of those Griefkit scopes too and I noticed the sweep runs 2x as fast as the switch setting says it is.  Any way to correct that?  That whole thing is an odd duck as the trapezoid pattern points left instead of right.

Speaking of scopes, anyone have a schematic for an RCA WO-57A?  Also need an 820 ohm, 2W resistor to fix an Eico.

Scott Todd