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Author Topic: Viking Ranger evaluate for rebuild  (Read 4346 times)
KA4LFP
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Posts: 257




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« on: August 22, 2017, 04:08:08 PM »

Hi all -

I've been handed what I'll euphemistically refer to as the carcass of a Viking Ranger.

I'm considering whether it's worth trying to salvage or not.
Almost all of the parts under the deck are present, the two big transformers at the rear are present, the 6146, and all the variable capacitors, bandswitches, shafts, etc.
Tubes are missing, but I got several boxes of tubes along with the transmitter and tons of other parts in bins,
so I suspect the missing tubes may be in with some of those parts.
The face plate and vernier knobs and pointer were in one of the bins.

In terms of major components, what seems to be missing is the VFO, and the modulator transformer on the righthand side of the deck.
I do have a few different little metal boards in the bins, with tube sockets in them, which some of may belong in the Viking.
I know there's one such board with two tubes on the lefthand front corner, which I do have.

The VFO I'd like to consider just replacing with an Arduino or PIC chip based DDS VFO, as I've seen done
with other rigs, including I think the Ranger.

So - I'm trying to figure out what to evaluate first, to determine whether anything made of unobtainium is missing,
and the transmitter is even a candidate for a rebuild later on.

First thought is see if the transformers are working, and I guess that's as easy as pull the remaining final 6146
and try to power up on a Variac and see if all the voltages are present on windings?


Any ideas on how to check those voltages, or other things that should be checked for hard-to-repair damage
or other issues that might make it not worth considering for reassembly, and a DDS VFO?

73, Tim KA4LFP
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VE3CUI
Member

Posts: 15




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« Reply #1 on: August 23, 2017, 08:04:49 AM »

Hi Tim,

If the mod transformer is gone, simply replace it with a universal 15-watt type (15-watts being the minimum) mod iron…I did that here with an old Stancor-type on my Ranger-1, & it worked fine, remembering that the duty cycle for SPEAKING through a mod transformer allows you to use just HALF the "normal" recommendation, which is based upon a continuous tone.

Don't believe me…?

The PHYSICAL size of the 15-watt universal iron is the EXACT SAME SIZE as the "stock" unit that came with the Ranger!

Good luck with your project --- you already have the majority of unobtanium parts making it a very worthwhile restoration adventure...

~73!~ de Eddy VE3CUI - VE3XZ
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K1ZJH
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Posts: 3479




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« Reply #2 on: August 24, 2017, 09:07:11 AM »

I'd go with at least a 40 watt transformer.  You need 35 watts minimum to fully modulate that rig.

Pete
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VE3CUI
Member

Posts: 15




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« Reply #3 on: August 24, 2017, 12:25:23 PM »

Hi Pete,

True --- if you are modulating it with a continuous tone…but the duty cycle of ordinary speech says that you can get away with just HALF that amount.

It's documented in the early edition of the ARRL's "UNDERSTANDING AMATEUR RADIO," too…and the size of that Stancor universal replacement that I installed in my Ranger was practically the EXACT SAME SIZE (physically) as the original, too --- not half as big, at all, despite its supposed reduced power handling capability…

Eddy VE3CUI - VE3XZ
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K1ZJH
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Posts: 3479




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« Reply #4 on: August 24, 2017, 01:33:09 PM »

You're achieving 100% high level plate modulation on a 75 to 90 watt (DC input) Class C final in a transmitter using a 15 watt modulation transformer... 

but, you still have to provide enough audio to achieve  4 times peak carrier at 100% modulation to have a square law power response.  I would question whether an under rated transformer would do so without saturating.  The speech waveform affects the duty cycle, but peak power requirements remain. I'm a bit skeptical...

 https://www.w8ji.com/amplitude_modulation.htm

Peter
« Last Edit: August 24, 2017, 01:49:48 PM by K1ZJH » Logged
K1ZJH
Member

Posts: 3479




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« Reply #5 on: August 24, 2017, 02:10:01 PM »

Tim,  check out these pages:

http://faculty.frostburg.edu/phys/latta/ee/ranger/restoration/restoration.html

If I was doing the work. I'd get it working 100 percent on CW before buying parts for the
modulator.

Pete
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K3STX
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Posts: 1597




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« Reply #6 on: August 24, 2017, 07:22:04 PM »

The VFO I'd like to consider just replacing with an Arduino or PIC chip based DDS VFO, as I've seen done
with other rigs, including I think the Ranger.

This is the most grotesque thing I have read in a long time. If you can't repair a nice old radio with nice old radio parts you shouldn't do it.

What kind of satisfaction could you possibly feel making an AM QSO with a solid state VFO?

Sounds like DON'T BUY THIS (shell of a) TRANSMITTER to me.

paul
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KM1H
Member

Posts: 3107




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« Reply #7 on: August 25, 2017, 05:41:38 AM »

A DDS VFO would be a good idea if you plan to do roundtables as retuning for the drifters is a real PITA; this isnt the 1950's. And the drift increases as the output frequency is multiplied such as 4X the 40M fundemental to get to 10M.
With all the SDR's and other modern gear owners now on AM they would appreciate it.

You could also use one of the better external vintage VFO's such as the WRL 755A or one of the hetrodyne types.

The Johnson 122 VFO is the basis for the Ranger and Valiant where they run way to hot with minimal attention to temperature compensation.
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VE3CUI
Member

Posts: 15




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« Reply #8 on: August 25, 2017, 06:50:36 AM »

Hi Pete,

Then the Johnson engineers who first came up with the Ranger musta cut a lot of corners when it came to the AM mode…!

You ever seen a Ranger, up close & personal…? Compare the physical size of the original mod iron, to that of a universal 15-watt unit --- better still, find a 35-watt replacement mod transformer, & try & wedge it into the space occupied on the chassis by the original iron!

Can NOT be done --- I know, because I tried when my Ranger-1 mod transformer expired some years ago…

Eddy VE3CUI - VE3XZ
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N4MQ
Member

Posts: 154




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« Reply #9 on: August 30, 2017, 10:20:49 AM »

I just redid a ranger and washed the chassis with brake cleaner to clear the tobacco. Rebuilt the broken band switch, did the low heat changes per the article posted previously, did the solid state power change and added new caps. Replaced the cord and added a fuse and inline voltage drop xfmr to 110 vac. Stripped the panel off and sent it to radio daze to get them to create decals for the ranger.  Got the panel back -stripped the paint and repainted it and redid the lettering with the great decals. The kit they now sell has 2x of each label for the oopse events.

Went thru the calibration and alignment of vfo, fixed a mangled tank and got it on the air, with positive results.  Had to retube most of it but it looks great today next to my drake 2b, waiting for 160 m season to return.  Work yes but it was positive even when I was polishing the vfo vernier ball bearing plates to get rid of a lumpy dial feel.

If you have the motivation and time, have at it. Iam into a thunderbolt amp to complement it and hope to get it running this fall.  Enjoy W  Grin  Grin D Y
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N2DTS
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Posts: 764




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« Reply #10 on: September 01, 2017, 08:51:51 AM »

I would buy another ranger and combine the best of two radios into one nice radio with a few parts left over.
Stock and/or lightly modified can be a nice rig, and 160 to 6 meters I think!
There are loads of upgrades as well.

Almost every old AM rig was built to a low price point and used shortcuts and under rated components.
Only a few were well designed, like the Collins 32V series and some of their bigger transmitters.
And they were priced to match.

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KM1H
Member

Posts: 3107




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« Reply #11 on: September 02, 2017, 05:40:55 PM »

Quote
Stock and/or lightly modified can be a nice rig, and 160 to 6 meters I think!

There are loads of upgrades as well.

160-10

For the Ranger II they dropped 11 and added 6.

If it was mine Id convert 11 to 12 which can be real nice AM band

Carl
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