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THE AM BULLETIN BOARD => Technical Forum => Topic started by: WD4DMZ on February 03, 2018, 05:43:58 PM



Title: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 03, 2018, 05:43:58 PM
A Ranger 2 followed me home from the Richmond Frostfest today. I was not looking for one but this unit was too clean to pass up. According to the seller it was an estate sale find. The caveat is 'as is' and working condition unknown.

First, the face is extremely clean... almost as new. Some paint has flaked off of the cabinet but no rust or corrosion. It looks as if the owner used it very little. No scratches, finger prints, smudges or worn printing. It had been covered so not dusty inside. No bad smell. Except for a new power cord it appears un-modified with original caps.

As tempted as I am I will not power it up until I get some guidance from those with experience on the R2. I do have a variac.

So, where to begin?

Thanks, Rich





Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: N1BCG on February 03, 2018, 06:11:58 PM
Congratulations! Those rigs can adhere themselves to our sides. First of all, use an Ohmmeter to check that there are no shorts in the LV and HV supplies. Next would be to fabricate a safety circuit consisting of a 60 Watt bulb in series with the power cord.

Using an extension cord you don't need, cut one lead and connect each lead to a regular bulb socket. I use a porcelain socket. Screw in the bulb, plug the Ranger into the cord and plug the cord into the wall.

Now, even if there's a ferocious short, the worst that will happen is the bulb will glow brightly. The rig won't be getting full voltage but you should be able to operate it in a limited way. Put in a 100 Watt bulb if things look good. After that, a direct plug-in should be safe.


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: KB2WIG on February 03, 2018, 06:53:04 PM


After the bcg treatment, you'll probably need to replace the Chernoble resistor. Search for it here on the site, you'll find it.

Add a 3 prong plug.

Add a fuse on the 'hot' side of your power cord (on the inside of the transmitter).


It wouldn't hurt to change out the bias capacitor  C90 a and C90 B. Its a + gnd for these caps; I'd replace them with more than 50 uF.

This should start things off.

klc




Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 03, 2018, 07:01:38 PM
Excellent advice. Thanks.

I will use the 60 watt bulb limiter. Have one right here. Should I also slow cook it on the variac for a while before full voltage?

I have heard of the chernoble resistor. Which one is that? Which circuit?

The replacement cord has the original plug with each leg fused. I agree with the three prong plug and usually do that on a boat anchor project.

One concern I have is that the paint is sooooooo good. Usually I am dealing with a scratched and worn radio. My bench will be covered with a thick towel.

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: N1BCG on February 03, 2018, 07:21:45 PM
Yes, the variac into the light bulb circuit. I also should have mentioned that it's the black wire (hot lead) that the bulb should be added to. You'll quickly notice if the bulb lights up "too brightly" as you increase the variac voltage, indicating an issue.

...the paint is sooooooo good.

Pictures, please ;-)


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: w8khk on February 03, 2018, 07:37:15 PM
You might consider this overly cautious, but when it comes to personal safety, I believe it is the highest priority.

I would get rid of the fused plug, and install a three-wire power cord before doing any further testing.  The problem is that any overload that takes out a fuse in the plug may open the neutral (cold) instead of the hot fuse.  That leaves the transmitter apparently dead, but lurking inside is the full 120 volts!

Another thing I am anal about is making sure the variac, and power receptacle, both have a good ground.  Many variacs are two-wire devices that do not have a grounding receptacle.  There is no difference between the old and new variacs, other than the fact that the newer ones have the green grounding pin on the plug and the receptacle, and this wire is attached to the housing of the variac. 

Have fun bringing up that nice rig, but please be careful!


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: KB2WIG on February 03, 2018, 09:37:44 PM


" I have heard of the chernoble resistor. Which one is that? Which circuit?

"

VFO Ckt., R3   18K  2Watts
.......  the Voltage Regulator tube dropping resistor.    The original is around 2 Watts; I replaced mine with a 18K, 10 Watt resistor. There's some discussion of changing the resistor value, and where to place the replacement, so you can search and see which one you agree to.

klc


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 03, 2018, 11:35:08 PM
Thanks for the info on the resistor. I'll likely up the wattage as you did.

So far tonight I have powered it up in the stby position thru a variac and a 60 watt bulb. The voltage on the xmitter was only about 30 volts. No noise or smoke and the pilot light was barely on. Graduated to a 100 watt bulb and brought the transmitter up to 50 volts. The pilot light was much more visible and the filaments began to glow.

So far, so good. The transformer primary winding appears to be OK.

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: N1BCG on February 03, 2018, 11:57:45 PM
Since the caps are original, it would be preferable to bring the voltage up in steps. Try running the Ranger through the 100W bulb for an hour or so and note any changes in brilliance or meter readings (if you get any at that voltage).

At that point you would have noticed any hard shorts so you could switch to just the Variac and start measuring the power supplies as you increase the supply voltage. At some point the oscillator will start to work so you should be able to hear it (in spot mode) on a nearby radio.

Do you have a manual?


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: MikeKE0ZUinkcmo on February 04, 2018, 11:21:05 AM
This transmitter draws around 130 watts after its warmed up (minim power drain configuration) and draws nearly 200 Watts peak at start-up.   So, to get even 50-60 Volts into the unit you'll need a 150 Watt bulb, and the rectifiers probably won't even be conducting yet.   IMHO a BAD idea.

I suggest the following:

First, check the fuses in the power cord, there should be a 3 Amp fast blow and a 5 Amp slow blow.   If you have an isolation transformer, use it.   If you want to install a 3 wire, you'll have to also install a fuse holder somewhere, be careful there isn't much room on the rear apron.   Another option is to use an internal fuse holder, but I'd consider that a real PITA. 

Then, you should read the start up procedure in the manual a couple times, followed by the "tune up" procedure.   

Use your Ohm meter and check for shorts to ground at the high and low B+ filter caps.   Don't forget, there are bleeder resistors so a reading of a few "K" ohms should be expected.   Next check the resistances in the manual, on or around pages 21 and 22.    Finally check for shorts from the AC POWER to chassis.

If you have an adjustable High voltage source of a couple hundred volts with a current meter, connect the high voltage to the radio's filter caps and ramp up the voltage, with the transmitter NOT connected the AC power.  If the current settles and doesn't increase for a minute or two, or, if the resistance reading above is OK, all should be good enough for a trial power up.   Disconnect the external power supply.

Plug your transmitter into a Kill-A-Watt meter, place the meter in the "Watts" position, then turn on the transmitter power switch to the standby position.

Closely, watch the Watt meter, it should peak for a second or two, then start displaying lower readings, and continue going down for the next several seconds.  It will stabilize, and slowly increase across the next 30 seconds or so, approaching it's normal power consumption level in the 130 Watt, +/- maybe 10% area.    You might also check some of the voltages listed on pages 21/22 as well.

Power off, wait a minute or so, and touch the body of the filter caps to see if they seem warm, if so replace them.   If not, hook up a dummy load, RF Watt meter, and Microphone.  Power it up again, follow the "tune up" procedures, and see if it works.

Mike


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 04, 2018, 03:32:50 PM
Good advice all. Good idea on the kill a watt. I'll use it. Have a manual as well (BAMA).

Currently up to about 90 volts on the variac and all is well.

Question... the manual refers to using the buffer control when tuning. No buffer control. This radio has an exciter control below and to the left of the VFO knob. Is that what the manual is referring to?

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: KB2WIG on February 04, 2018, 03:57:34 PM



The   EXCITER.



Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 04, 2018, 04:53:59 PM
Learning a lot here.

Right now the line voltage thru the variac is 110. In standby the unit is drawing 128 watts. When I switch phone it is 210 watts. Close to what you describe. Good idea to use the KAW meter. Nice gadget.

There was some jumping around of the meter but that turned out to be dirty contacts on the switch. I am watching it closely now.

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 04, 2018, 05:30:23 PM
The inspector tag is intact on the rear cabinet. The SN is 1373. Is there any way to date the radio?

Also, the prior owner had affixed a T/R relay to the SO239 and it is functional. The seller had a mike plug as well so I now have a mike wired and ready to go. Tomorrow I shall give it a try if everything checks out.

The VFO is pretty close to the calibration on the dial and I have a 7290 xtal in it as well. That is where I'll start.

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: N1BCG on February 04, 2018, 05:37:04 PM
Sounds like things are shaping up nicely... congrats!


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: MikeKE0ZUinkcmo on February 04, 2018, 08:57:13 PM
Glad to be of help and that all is good so far.

Mike


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: W9BHI on February 05, 2018, 10:09:57 AM
I find it puzzling as to why people immediatly replace the dreaded "chernoble" resistor.
I have rebuilt over a dozen Rangers and Valiants and have yet to find a bad 18k resistor in any of them.
Just making an unsolicited comment.
Don W9BHI


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: w4bfs on February 05, 2018, 10:44:47 AM
the resistor in an unmodified Ranger working at 110 Vac is within dissipation ratings.  When you operate the transmitter at 120Vac or modify the rig to solid state power supply the increase of the low B+ voltage is what causes the resistor to overdissipate.  This is why it is correctly stated that power supply changes are going to require a system level evaluation and approach for correct operation.


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 05, 2018, 02:18:55 PM
This radio is in such good condition I am not going to do any mods. All the readings are good and today on a noontime AM forum it performed well and the audio reports were great.

The voltage is an issue. The manual calls for 117 VAC, not 110 VAC. However, the line voltage in my area is 120 V and sometimes higher. I'm running it on a variac to keep the voltage below 115 VAC and it seems to be happy at 110 VAC so might just run it there.

I will not run it very much as my Viking 2 is my main AM rig so will not worry about the resistor unless I smell something cooking.

The one component I am considering changing is the 10 MFD 700 VDC electrolytic. If it failed that could do some damage. I do not have any 700 VDC caps on hand but plenty of 450 VDC caps. Could I put two 20 MFD 450 VDC caps in series? I have heard of pros and cons on doing that unless adding some resistors as well. Any comments on that?

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: N1BCG on February 05, 2018, 03:31:16 PM
Exactly. Using two filter caps in series to increase the voltage rating is a common practice with a voltage dividing resistor in parallel with each cap. These don't need to draw much current so even 1W components can be used (470k each for example). The reason is to ensure that neither capacitor has to operate above its rated voltage.

The downside of this is the halving of the total capacitance, but it seems that you already are aware of that.


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: N1BCG on February 05, 2018, 03:43:36 PM
I find it puzzling as to why people immediatly replace the dreaded "chernoble" resistor.

I have the original in my Valiant as well, but there have been widely publicized cases of the aging resistor's value dropping as it heats, creating a bad cycle. Eventually the voltage regulator tube gets destroyed and the damage goes from there.

It's a preventative move...


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 05, 2018, 05:23:36 PM
Here it is:

https://imgur.com/a/fOAEg


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: MikeKE0ZUinkcmo on February 05, 2018, 11:53:58 PM
Nice looking example.  Much better looking than mine (https://mikeharrison.smugmug.com/EF-JOHNSON/Ranger/i-JwvKTvV/A), but I didn't pay much for mine either.

As for the resistor, if it looks well "cooked" I'll put in a higher power rated version.   I did it in this 122 VFO (https://mikeharrison.smugmug.com/EF-JOHNSON/Big-Pics/i-xrqZHjj/A) a while back.

 



Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 06, 2018, 11:28:41 AM
Nice pictures Mike. Thanks for sharing. It is great to see how you made your modifications.

There was a Ranger for sale at the Richmond Frostfrest. The price was $375 and the seller would not budge. He said it was working and had all the mods but the power cord was actually crumbling with copper exposed so it was not likely it had been powered up in a long time. The exterior condition was pretty nice though.

The Ranger 2 I brought home was across the aisle. Somewhat buried on a table with a lot of other stuff but the nice condition of the front caught my eye. I deliberately brought under $300 to keep me from spending too much. Near the end of the show I asked about it but the seller wanted $350. After buying some miscellaneous item I had only $270 in my pocket and he accepted that. It came with the Dow Key T/R switch and 2 mike connectors. It works well so I'm glad I took a chance on it.

I was actually looking for an NC183D but this is a better find.

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: KG6PQQ on February 07, 2018, 01:01:23 PM
I got the third Ranger that was towards the middle of the room.


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 07, 2018, 07:10:20 PM
Hmmm. I missed that one. Any pictures? Did you see the one with the crumbling power cord? Aside from the cord it was pretty clean.

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: KG6PQQ on February 16, 2018, 11:49:53 AM
The cord is frayed, Iím replacing the cord with a filtered fused socket


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 16, 2018, 01:21:47 PM
That is a nice one. I'm surprised I missed seeing it unless you purchased it early in the morning. I did not get there until 11:30.

Looks like a great find.

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 17, 2018, 10:23:13 PM
At present I am accumulating parts to recap the R2 as it is all original.

Looking at a Phil and Tim's Ranger rebuild sites 1,000 volt ceramic disc caps are recommended in a few spots. I have some of them on hand but not all. My largest ceramic disc cap is .01 mfd.

For instance, one value is a .1 mfd cap and what I have are Sprague 1,000 vdc orange drops. Is the orange drop ok? Also I have some maroon colored drops.

They also recommend much larger values for the electrolytics. I have a supply of many ratings on hand but do not want to go too large. The manual actually has a +100%/-20% spec so the ratings must not be that critical in the HV supplies. To replace the 10 mfd 700 VDC cap I have two 33 mfd caps in series with two 470k ohm flame resistant 1 watt resistors ready to go.

I have 1N4007 diodes on hand and may replace the 6AL5 bias rectifier as that is any easy upgrade. Is that ok to do without replacing the HV tubes as well?

Any advice appreciated.

Thanks, Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: KB2WIG on February 17, 2018, 11:20:01 PM


Well.... if yer gonna start playing with the boat anchors, your going to need parts....

A quick walk through the Ranger 2 manual  lists  (36), .005  600 volt disc ceramic caps....   You can get 36 caps from Mouser for $7.20 plus shipping. .005 is a common cap, and you'll be well served by purchasing more than you need now. Its easy to spend someone's else money - so I'd suggest that you buy several more of what ever you need, and you'll soon have a nice supply of parts.

But.....

I doubt that any of the ceramic caps in your Ranger need replacing. But if any do need replacing, its nice to have things on hand. When ever I break down and buy parts from Mouser, I'll flesh out the order by buying a few dollars worth of resistors or capacitors- I bought several hundred 1n5408 diodes- The are 1kV, 3 A diodes, and I'll not have to buy any for a while. I pretty much use them anywhere a rectifier is needed (I still have a lot of 1n2007 for things like the 6al5).   And then there's the ham fests.

klc.


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: MikeKE0ZUinkcmo on February 18, 2018, 04:41:04 AM
I've bought many components just to have on hand.   It's needlessly frustrating to start a project and find I have to put it on hold for some 2 cent part.   As a general rule, ceramic disc caps don't need replacing.

l would recommend you stick with electrolytics and paper caps if you just want to replace something carte blanche.

Quote
...and what I have are Sprague 1,000 vdc orange drops..
Depends on where they are used.  

There is a chart about half way down this page (https://electronics.stackexchange.com/questions/177575/capacitor-selection-for-filtering-of-low-level-signal) you may find useful, regarding the various capacitor types and the circuit they may be used in.   Of course as in anything electronic, there are other factors to influence your final decision, but this gives a place to start.

If you want to replace the rectifiers, I'd put some series resistance in the string as well, if for no other reason than to  reduce inrush current.   I used 100 Ohm, 5 Watt (https://mikeharrison.smugmug.com/EF-JOHNSON/Ranger/i-mPH54GT/A) wire wound resistors, to somewhat compensate for the original tube rectifiers internal voltage drop at the expected load.   A quick look at the tube manual will give you what you need.


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 18, 2018, 08:34:59 AM
Good morning. Good advice.

I was going to leave the discs in place and replace only electrolytic and paper caps. The question arose because the two R2 rebuild sites I referenced specified 1000 V discs to replace the paper caps. Most of the paper caps in question are rated 400 V or lower so the normal mylar and orange drop caps rated 600 v should be fine.

Everything in the R2 looks good after two weeks of operating it so I am in no hurry to replace anything, just amassing the parts to do it all at one time.

There are many mods listed but I plan to leave it mostly as built so the next owner (decades from now I hope) will have a good example of an R2.

Regards, Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 18, 2018, 11:30:45 AM
There is one paper cap that concerns me  - C69 - a 1,600 Volt .02 mfd in the audio circuit. It looks ok but if it were to fail I suspect there could be fireworks. I have seen no reports of one failing but will replace it while I'm in the radio.

Am I over concerned?

Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: MikeKE0ZUinkcmo on February 18, 2018, 05:39:54 PM
I'd guess the R2 only has one, across the modulator transformer.   Some of the early R1s had two.  Wouldn't hurt while you're in there.


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: KB2WIG on February 18, 2018, 06:22:07 PM


I replace my C69 with a 1600 V , .0022uF Orange drop. 'Cause that's all I had.


klc


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: WD4DMZ on February 18, 2018, 09:14:09 PM
About 4 years ago a gent I knew passed away suddenly and left his family his huge collection of old radios and TV sets. He also had a large stock of caps and resistors etc. I purchased the small components - many hundreds of well organized pieces - and after going thru the boxes today there was a box of 1600 volt caps. These are made by Mallory in dark maroon (mylar?) so should be good products.

Good news is that there are a few .02, .01 and .068 mfd caps in the mix so I am all set.

If this is not a critical value as WIG noted I may go with the .01 because it is much smaller than the .02.

WIG... Did the .0022 have any bad effects?

Thanks, Rich


Title: Re: Johnson Viking Ranger 2 Advice Requested
Post by: KB2WIG on February 18, 2018, 10:49:02 PM


No, not that I'm aware of. If I remember correctly, reducing the capacitance increased the audio frequency response a bit. If you have problems, just tack another .01 across the .01 and yer back to where you started .

I'll add another bit ' advise.  Since you have it working, only make one or two changes/replacements at a time. If you screw up, you'll save a bag of time with only a few things to check. I love my camera ( yeah, I bought a digital cam  around '05 to document what I did.)

klc
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