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THE AM BULLETIN BOARD => Technical Forum => Topic started by: WB2PKR on February 17, 2018, 10:56:37 AM

Title: Troubleshoot Viking Ranger II
Post by: WB2PKR on February 17, 2018, 10:56:37 AM
Went to lunch with an old friend this week and came home with his Viking Ranger II. I’ve admired it for a very long time. It just sits there unused on his spare parts shelf looking like it just came out of the box.
He said it worked the last time he used it about 10 years ago but it had some audio issues. The price was right and cosmetically it looks super nice, so I figured it would make a good winter project.   :-\

I have the original manual and receipt as well as a change/repair log from original owner but it only documents the changes from 1962 til 1975. It appears many more mods were subsequently made without any doc.
Im hoping that someone here might recognize some of these mods and if possible might even have doc/schematics of the changes and/or give me some more specific suggestions on shooting the problem.

According to him, this rig was restored and modified by Dee (W4PNT). Upon inspection, I can see it is definitely not stock/original design. In addition to being recapped, I can see all sorts of mods. Most the caps have been replaced except those “domino” looking micas. The Chernobyl resister was replaced and relocated outside the VFO enclosure.  The LV and HV tubes have been replaced with diodes. There is a pot where the crystal socket was located that is connected to some sort of SS voltage regulator that seems to control grid current (possibly the Turbo Mod I read about (W3AM)??. The modulators have been replaced with 6550s. The HV bleeding resister has been removed. There seems to be some sort of PTT circuit added. Its a really pretty Frankenstein.

I finally got an account here (Thanks John) on AMfone and I been searching/read through all the Ranger posts I could find.

Here is what I have done so far…

Visual inspection. Electrolytics all look OK. No visual signs of any fried components.
Connected to watt meter and dummy load. No mic. No key.
I used BCG’s 60W lightbulb fuse approach and the rig came on no problem with the rectifiers pulled. Same after plugging the LV rectifier back in and then subsequently, the HV rectifier. No pops, no fuses blown, no breakers tripped.
I pulled and checked all the tubes, except the two in the VFO enclosure. They all are OK and they all are the original spec tubes except the rectifiers and modulators as previously described.
I was able to follow the instructions to initially tune up the rig. I peaked the exciter and could zero beat it on 3700 listening on my receiver.
In tune position I could also see some grid current but the driver did not affect it. Neither did that pot in the crystal socket.
When I switch the meter to plate and try to dip, no dip.
Connect straight key to key jack. switch to CW, key down plate current meter moves left. less than 1W out.

My next steps would be to start checking voltages as per the manual, but what about all these mods? Does anyone recognize any of these and if so, would you please provide some insight on how to proceed.
Thanks.  Ron WB2PKR

Photos attached...

Title: Re: Troubleshoot Viking Ranger II
Post by: KB2WIG on February 17, 2018, 11:45:16 AM


Welcome a bord.

You may wish to check out this,  on the AM Window seister site.


Title: Re: Troubleshoot Viking Ranger II
Post by: MikeKE0ZUinkcmo on February 17, 2018, 12:06:18 PM
My suggestion would be to google "viking ranger mods" and similar queries.  The goal is to print out as many of the various modification documents as you can find, and start comparing them with your radio.   As you mentioned, at first glance it looks like the audio may have been modified per a circuit from W3AM I think it is.

Aside from 6 Meter provisions, there is little difference between the Ranger and Ranger II, so most of the mods would work on either model.

The data gathering/evaluation process will take few hours to fully determine "what it is you have", but once you know what you're dealing with, you'll have a good idea what you would like to keep, and what you would like to do, or undo as the case may be.

Title: Re: Troubleshoot Viking Ranger II
Post by: WB2PKR on February 18, 2018, 08:29:56 PM
WIG, thanks for the link.
Mike, yes, google is my friend.

It appears this rig has some of Tim's audio mods, some of W3AM's turbo mods (grid control) and some other (PTT) mods.
Still reading, researching and sketching out some drawings that accurately describe the mods. Once I understand what I have I will report back and then dig into to try to find root cause.

I was hoping someone might recognize some of these mods and shed some light. Oh well, troubleshooting is half the fun. Back to work.

Thanks again for your replies.


Title: Re: Troubleshoot Viking Ranger II
Post by: WA1HZK on February 19, 2018, 06:30:34 PM
My Ranger mods are here.

I do have the documents if you don't have them already.

Title: Re: Troubleshoot Viking Ranger II
Post by: WB2PKR on February 22, 2018, 08:23:52 AM
Keith, thanks for the link. Nice photos. Hand written notes especially helpful. 73

Title: Re: Troubleshoot Viking Ranger II
Post by: WB2PKR on March 17, 2018, 06:41:38 AM
Brief update and some questions...

Gave up on trying to find schematics for the mods as nothing I found was accurate. That said, in addition to links mentioned above, I found these links very insightful…;topic=19981.0

Decided to just jump in.
In cases where the circuit didnt match the doc (i.e. mods) I just measured components to see if they matched the stated value on the component.

After warming rig up on variac to 115V, I fired it up again. This time after a few minutes, I heard a pop and saw some smoke. Using my nose it wasnt hard to find a smoked R13 (drive pot).
I ordered two replacements (ya never know), and while waiting for the parts to arrive I put some fixed ceramics in its place and continued to troubleshoot. I also removed the 6146 and put a plastic bag over the plate connections.

I then checked voltages and resistances on page 20 & 21 in the ranger manual which lead me to issues with the buffer/multiplier circuits.  Replaced a few shorted caps (C24, C33 & C34) and a few resistors way out of whack (R11, R44). After hitting the wall, I “phoned a friend” and “we” realized that although V4 tested OK on tube tester, it was not working. (The scope is invaluable for this kind of work. I never used one prior to this project and with the help from Elmer, we quickly found the culprit)
We also noticed that the keyer tube , V14 was apparently replaced with a 12AX7A as opposed to the stock 12AU7. Still not sure if that was a mistake or if someone put the higher output amp tube in on purpose. (Anybody?) Regardless, I replaced it with a 12AU7 and I replaced the 6CL6 V4.

With replacement pot installed. she fires up nicely now. 40W carrier into dummy load. 75W+ with audio on peaks.
On 160, the audio is very clean, warm and wide with D104.  Pretty much same on 40. On all other bands, there is a very loud hum or buzz.

I temporarily moved the screen voltage mod pot from in front of the crystal socket and I rewired the crystal socket to the switch so I could check with crystals instead of VFO. No change. bad hum.

Could it be the filament bad grounds as Timtron suggests? If so, why are 160 and 40 so clean? I will reground all the filaments as per Tim. As well as the replace the filament terminal strip mounting rivets with screws, nuts and star washers, but if it was a filament ground issue, why is audio on 160 and 40 so clean? Any other things to check?

OK, thats all for now… Back to the bench…

Title: Re: Troubleshoot Viking Ranger II
Post by: WD4DMZ on March 17, 2018, 08:42:51 AM
Good info. I'm following this as I picked up an R2 about 6 weeks ago. Fortunately un modified and so far functioning well.

As the drive pot may become an issue, where did you order them from? Part #?

Thanks, Rich

Title: Re: Troubleshoot Viking Ranger II
Post by: WB2PKR on March 17, 2018, 09:10:30 AM

Title: Re: Troubleshoot Viking Ranger II
Post by: KB2WIG on March 17, 2018, 10:29:15 AM

You may wish to take some of the stress off of the drive pot.... there is a solod state method on  the amwindow site or use some added resistance.

AD5X has a Ranger restoration  using a 5K 5 Watt and a 7.5 K 5 Watt modification in conjunction with the pot... check it out and leave your drive pot worries behind. Do it for the children.


Title: Re: Troubleshoot Viking Ranger II
Post by: WB2PKR on March 17, 2018, 10:31:29 AM
AD5X link...

Title: Re: Troubleshoot Viking Ranger II
Post by: W3GMS on March 17, 2018, 08:09:58 PM

I knew Dee-W4PNT pretty well and visited him on several occasions when he was painting Johnson gear.  I do remember he had a list of mod's which he did for customers that did not want to do the mod's themselves.  His changes were fundamentally sound.  At one time, I knew the changes he did, but that was many years ago and I forget the specifics.   Dee and Howard-W3HM were good friends and Howard may have a list of the mod's that Dee did on the Ranger's.  Not sure, but I would send Howard and email and ask the question. 

I have owned a Ranger II for 35 years ago and its my daily go to rig to drive a legal limit amplifier.  A great rig and with some mods can even be a better rig.  I have never had a failure since I did mods on mine some 25 years ago. 

Some folks, me included, used the pot to vary the gate voltage on a N channel FET acting a series pass going to the screen of the 6146.  It allows one to easily tweak the output power when driving a linear amplifier. This pot was commonly located around the octal socket used as a XTAL socket.  I mounted my pot behind the socket and this allowed me to keep all XTAL functions.  You simply put an insulated alignment tool into the hole in the center of the socket and then align it with the slot in the pot shaft.  In mine, I power the 6146 off the LV supply.  This gives me the perfect drive level for a pair of 3-500Z's.  The second mod that is very common is to use the same scheme that was just described on the screen of the driver tube.  Replace the drive pot with a much higher value which lowers the stress since the series FET is doing all the work. 

6550's as modulators are a common mod as well.  In my case, I used a hot cathode phase inverter to drive the grids and this allowed me to get rid of the driver transformer.    I used a shunt zener diode scheme to bias the 6550's so they would not pull any grid current.  I also used another FET as a screen regulator for the modulators.  This keeps the screen voltage very constant. 
Not saying what mods you have, but some may be along the lines I described.  I do remember talking to Dee with his Ranger mods and the on air signal sounded very good. 

Dee was a great guy and is missed by many. 



Title: Re: Troubleshoot Viking Ranger II
Post by: N1BCG on March 17, 2018, 10:53:02 PM
At some point, you’ll need to decide if you want to refer to your rig as a Ranger or not on the air. A Ranger sounds like a Ranger, although many sound great with very minor mods. After enough modifications, it’s a Ranger in looks only.

Title: Re: Troubleshoot Viking Ranger II
Post by: WB2PKR on March 18, 2018, 07:38:57 PM
The hum was in fact from the filament supply. I replaced the rivet holding the terminal strip at the transformer with a screw, star washer and nut. That did it.  It is now pretty quiet on the dummy load. Going to try it on the air tonight.


Title: Re: Troubleshoot Viking Ranger II
Post by: WB2PKR on March 21, 2018, 06:20:32 PM
Reports on the air are solid. No hum, good clean audio. Working on all bands (except I didnt try 6M).

So, some final observations, lessons learned and maybe a punchlist item or two:

- I spent too much time worrying about trying to find schematics for all the mods. Should have jumped in earlier.

- Learning how to use a scope was invaluable in shooting the problems. If you dont have one, get one or borrow one and learn how to use it. I wasted a lot of time checking component values and voltages/resistances when simply connecting the scope to the multiplier would have quickly shown me the 6CL6 wasnt working despite it checking out OK on the tube tester.

- As pointed out by Joe (W3GMS), it appears that pot installed on the crystal socket does indeed vary the screen voltage, but I wonder about this mod. Not sure I like this one. I would think that reducing screen voltage will impact the quality of the signal.  Regardless, I currently have it set wide open, but I am considering removing it as I have no plans to reduce output to drive an amp.

- That drive pot (R13) I replaced runs VERY hot. Kevin, thanks for suggesting the AD5X mod. I may do this next time I open up the rig. Right now it is assembled and off the bench in the operating position. Maybe get to this one over the summer.

It has been a fun and educational little project. Albeit, I spent WAY more time than I estimated. Good thing it is still too cold for boat work.

Thanks again to those who provided constructive comments and input.

Catch you on the bands.

73, Ron WB2PKR
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands