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AD0IU
10-21-2007, 04:48 AM
Hello:

I've begun a restoration of my Viking Ranger & have two questions:

First:
L10, the rf choke on the 6146 plate seems to be pitted/scorched. I'd like to replace it but there are no specifications in the Ranger manual (it just says RFC). I've read elsewhere that it is probably 2.5 or 3.5 mH choke, but I'm wondering about the Q, test freq and self-resonant frequency values because there are many combinations to choose from. Any suggestions?

Second:
Anyone know a good source for small (25-50ft) spools of 16 AWG, 1000V wire? The power transformer lead insulation can best be described as "crunchy" and disintegrates with little prompting. I want to cut the leads back (almost to the winding) and splice on some new, less crunchy, wire. I don't really need 100ft, though.

Thanks,
Rob

W9GB
10-21-2007, 11:14 AM
Quote[/b] ]Second:
Anyone know a good source for small (25-50ft) spools of 16 AWG, 1000V wire? #The power transformer lead insulation can best be described as "crunchy" and disintegrates with little prompting. #I want to cut the leads back (almost to the winding) and splice on some new, less crunchy, wire. #I don't really need 100ft, though.

Rob -

I will take the second question, first. #
You can find Belden or Alpha "hook-up" wire with this rating in 100 foot spools -- sometimes you will find it in 25 feet spools as part of a multi-color/bench assortment pak. #Another option is the teflon wire (at these ratings) sold surplus on eBay.

IF this was my restoration (and reading and reviewing other Ranger restorations through the years) -- AND this was the original transformer -- I would send it to one of the amateurs (or commercial shps, like Heyboer) that will "rewind"/"rework" (120 VAC input, proper HV output voltage with a solid-state rectifiers, new teflon leads) this transformer (~ $50-$100) as required.
WA1HLR
http://www.amwindow.org/tech/htm/rangtron.htm

RF Parts should have any RF choke that you may require -- give them a call:
http://www.rfparts.com/choke.html#highrf

w9gb

KA4DPO
10-21-2007, 02:12 PM
Rob, It's a 2.5 Mhy RF choke. #The 2.5 Mhy choke rated at 200 ma on this page will work.

Link (http://www.surplussales.com/Inductors/Ind-RFCoils/Ind-RFCoils-6.html)



This will also work.

<a href="http://cgi.ebay.com/PLATE-CHOKE-FOR-TRANSMITTER_W0QQitemZ320170942084QQihZ011QQcategor yZ4671QQssPageNameZWDVWQ
QrdZ1QQcmdZViewItem" target="_blank">Linky</a>

W9GB
10-21-2007, 02:23 PM
Yes,

Bob at Surplus Sales will sell a 2.5 Mhy choke rated at 200 ma for &#036;14.95.
I wish he would put an accurate photo of his Omaha warehouse (north of Qwest center)on the web site

RF Parts will sell the same part for less than 1/2 that price .... and I have some from Dan&#39;s Small parts (a few yars ago) for less.

w9gb

10-21-2007, 02:24 PM
I will have one on the workbench soon, and there is one thing I would like to recommend. Look into replacing the cardboard electrolytic caps (C77, C78, and C52) as they may have broken down over the years.

C77 and C78 are big ones, one is 10uF at 700 V and the other is 30uF at 400 V. The last one, C52 (i think its 52, its one of the caps numbered in the 50s) is really 2 caps. They are 2 10uF @ 50 V and are wired together, their negative leads are tied together.

All of the caps I mentioned have axial leads, and I have found all of them at Mouser.

Just wanted to pass this along. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

KA4DPO
10-21-2007, 07:59 PM
Quote[/b] (KE5QYK @ Oct. 21 2007,09:24)]I will have one on the workbench soon, and there is one thing I would like to recommend. Look into replacing the cardboard electrolytic caps (C77, C78, and C52) as they may have broken down over the years.

C77 and C78 are big ones, one is 10uF at 700 V and the other is 30uF at 400 V. The last one, C52 (i think its 52, its one of the caps numbered in the 50s) is really 2 caps. They are 2 10uF @ 50 V and are wired together, their negative leads are tied together.

All of the caps I mentioned have axial leads, and I have found all of them at Mouser.

Just wanted to pass this along. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif
One easy way to replace the 10uf cap is to use two 20 uf caps at 450 volts in series.

KA4DPO
10-21-2007, 08:04 PM
If you can&#39;t find a 10 uf at 700v you can use two 20 uf caps at 450 volts in series. I did this on my Ranger and it works just fine.

By the way, I have restored two Rangers and still have the best one. The plate choke can be gotten cheap if you&#39;re willing to look. In deference to W9GB, you can probably find the parts for less but it depends on how long you want to wait. If you need any help with your rebuild please contact me.

John..

W9GB
10-21-2007, 08:09 PM
Quote[/b] ].... you can probably find the parts for less, BUT it depends on how long you want to wait.
Exactly. I have a couple of items that I have been restoring for over one year .. my patience and parts hunting waiver .. one eventually wins .. when I want it off the workbench http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

w9gb

AD0IU
10-21-2007, 08:22 PM
Thanks everyone,

I am going to make the mods suggested by AD5X AD5X Ranger Mods (http://www.ad5x.com/images/Articles/Ranger%20Mods%20RevB.pdf) and have identified sources for all those parts - should take care of the old capacitor problems.

I also may have found a source of 14 AWG XLPE wire which may prove suitable. The transformer rewinding my happen at some point down the road...but for now the winding resistances test within tolerance and I&#39;ll probably use what I have.

I&#39;ll keep you posted on the progress.

73,
Rob

10-21-2007, 11:08 PM
Quote[/b] (KA4DPO @ Oct. 21 2007,15:59)]
Quote[/b] (KE5QYK @ Oct. 21 2007,09:24)]I will have one on the workbench soon, and there is one thing I would like to recommend. Look into replacing the cardboard electrolytic caps (C77, C78, and C52) as they may have broken down over the years.

C77 and C78 are big ones, one is 10uF at 700 V and the other is 30uF at 400 V. The last one, C52 (i think its 52, its one of the caps numbered in the 50s) is really 2 caps. They are 2 10uF @ 50 V and are wired together, their negative leads are tied together.

All of the caps I mentioned have axial leads, and I have found all of them at Mouser.

Just wanted to pass this along. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif
One easy way to replace the 10uf cap is to use two 20 uf caps at 450 volts in series.
That is what we were planning on doing since the 700V caps are hard to come by. We even thought about putting 2 40uF 450 V in instead of 20&#39;s to improve the filtering.

KA0GKT
10-22-2007, 05:20 AM
Quote[/b] (w9gb @ Oct. 21 2007,07:23)]Yes,

Bob at Surplus Sales will sell a 2.5 Mhy choke rated at 200 ma for &#036;14.95.
I wish he would put an accurate photo of his Omaha warehouse (north of Qwest center)on the web site

RF Parts will sell the same part for less than 1/2 that price .... and I have some from Dan&#39;s Small parts (a few yars ago) for less.

w9gb
It&#39;s the old steam laundry building. Back when I was taking care of broadcast facilities in the Omaha area I really enjoyed visiting Surplus Sales of Nebraska. I remember getting replacment GR connectors for one station&#39;s GR hot bridge.

73 DE KAGKT/7

--Steve

W9GB
10-22-2007, 01:29 PM
Quote[/b] ]It&#39;s the old steam laundry building. #Back when I was taking care of broadcast facilities in the Omaha area I really enjoyed visiting Surplus Sales of Nebraska. #I remember getting replacment GR connectors for one station&#39;s GR hot bridge.
Bob had to move out of his old building/warehouse 2 or 3 years ago, and moved into what is left of old 19th century warehouses north of old Union Pacific shops (now part of the Qwest center redevelopment). #
My brother lives in Omaha, so I get out there at least 2 or 3 times each year -- unfortunately -- no walk-in like old Nortex in Ft. Worth, TX #(and that surplus center will be missed).

w9gb

K9STH
10-22-2007, 03:14 PM
GB:

Nortex (over in Fort Worth) is going to be reopened&#33; The details are not public at the present time but there was an announcement this morning.


JBY / QYK:

R3, which is the dropping resistor for the 0A2 voltage regulator in the VFO is notorious for causing problems. It is a 2 watt 18K resistor and is located in the VFO compartment. This needs to be replaced with a resistor of at least 5 watts capability and even higher if possible. Some people say to remove this from the VFO compartment. However, doing so actually reduces the stability of the VFO rather than increasing it&#33; Johnson designed the temperature compensation in the Ranger with the heat from this resistor included. Moving the resistor results in much more time being required for the VFO compartment to reach temperature (if ever) and thus more time is required for the VFO to stabilize.

Replacing the 0A2 with an 0B2 helps stablize the VFO as well. This reduces the screen voltage to 108 volts instead of 150 volts. The VFO works fine with the reduced voltage.

Replace the 6AU6 VFO tube with a 6AH6. This is a direct replacement. Doing this will definitely help with the frequency stability of the VFO. Heath had to make this replacement in the Apache transmitters (early ones had a 6AU6) to get the VFO stable enough for SSB. The only thing is that the 6AH6 has a slightly different interelectrode capacitance and you might have to &quot;touch up&quot; the variable capacitors used for frequency calibration. However, you should not have to adjust the inductors.

Glen, K9STH

W9GB
10-22-2007, 03:29 PM
Quote[/b] ]Nortex (over in Fort Worth) is going to be reopened&#33; The details are not public at the present time but there was an announcement this morning.
- Glen
Glen -

That is great news &#33;

Greg
w9gb

KL7AJ
10-22-2007, 05:51 PM
Quote[/b] (ka8jby @ Oct. 20 2007,21:48)]Hello:

I&#39;ve begun a restoration of my Viking Ranger &amp; have two questions:

First:
L10, the rf choke on the 6146 plate seems to be pitted/scorched. #I&#39;d like to replace it but there are no specifications in the Ranger manual (it just says RFC). #I&#39;ve read elsewhere that it is probably 2.5 or 3.5 mH choke, but I&#39;m wondering about the Q, test freq and self-resonant frequency values because there are many combinations to choose from. #Any suggestions?

Second:
Anyone know a good source for small (25-50ft) spools of 16 AWG, 1000V wire? #The power transformer lead insulation can best be described as &quot;crunchy&quot; and disintegrates with little prompting. #I want to cut the leads back (almost to the winding) and splice on some new, less crunchy, wire. #I don&#39;t really need 100ft, though.

Thanks,
Rob
The choke is not critical...it just needs to be at least 10 times the value of the tank coil inductance. Q is irrelevant in this case.

eri

AD0IU
10-22-2007, 06:24 PM
Thanks for all the tips.
Another place I&#39;ve looked at for surplus is Mendelson&#39;s in Dayton...may have found some wire there.

Glen:

Quote[/b] ]Some people say to remove this from the VFO compartment. However, doing so actually reduces the stability of the VFO rather than increasing it&#33; Johnson designed the temperature compensation in the Ranger with the heat from this resistor included. Moving the resistor results in much more time being required for the VFO compartment to reach temperature (if ever) and thus more time is required for the VFO to stabilize.

I have read of moving the resistor R3 outside of the VFO compartment. This is the first time I&#39;ve encountered anyone recommending keeping the resistor inside. That&#39;s one less hole to drill. I considered creating a mechanism that allows R3 to be inserted into or extracted from the VFO compartment during operation, similar to control-rods in a nuclear reactor. O.K...I&#39;m going off the deep end; I know.


Here&#39;s an interesting conundrum:

At the BAMA (Boat Anchor Manual Archives) site I&#39;ve encountered two schematics. One for an &quot;early version&quot; of the Ranger and one for a &quot;later version dated 10-17-57)&quot;. The later version has a bias rectifier (V14) and an extra tap on the secondary to supply the cathode voltage to this device. The earlier version lacks the bias rectifier (V14 6AL5) as well as a keyer (V13 12AU7). What it lacks in vacuum tubes it partially makes up for in capacitors - it has C76?, a .02mf 1600V capacitor tied to pin 1 and 9 of SW-4B and to a 220 Ohm resistor (R34) that goes to ground.

My Ranger has elements of both. It has both V14 and 13, like the later version, however it also has C76, R34 and a transformer with no bias rectifier tap. V14&#39;s cathode is connected to pins 3 and 5 of V12 (The plates of the low voltage rectifier - 6AX5-GT - which in turn are taps off the secondary of T1).

Has anyone ever encountered this arrangement? At one point in this radio&#39;s life (~1980-81), the resistors and a capacitor under the keyer platform were &quot;smoked&quot; and then replaced. I am wondering if the setup I&#39;ve described had anything to do with it.


73,
Rob

K9STH
10-23-2007, 01:45 AM
JBY:

There has been a lot of discussion on the various &quot;boat anchor&quot; reflectors over the past year about R3. A couple of guys actually tried it both inside and outside the VFO compartment and then made temperature measurements versus frequency stability. Both of these persons &quot;discovered&quot; that when R3 was inside the VFO compartment that the VFO stabilized sooner and that the long-term stability was better. The consensus of opinion was that Johnson included the heat from R3 when designing the temperature compensation.

It really is not that hard to get to R3. You do have to remove the side panel to the VFO but you do not have to remove the VFO from the transmitter.

As for the differences in the circuitry from either BAMA schematic: There are several possibilities including changes in production and the fact that Johnson had a kit for installing the keyer circuit in the early versions. This kit did not have the components for the bias changes.

Now for those reading this who think of a &quot;keyer&quot; in terms of something that makes &quot;dits and dahs&quot; the &quot;keyer&quot; in the Johnson Viking Ranger is a circuit that turns on the VFO before the rest of the transmitter and turns it off after the rest of the transmitter when the telegraph key is closed and opened. This is done to reduce &quot;chirp&quot; from being transmitted when a VFO is keyed along with the rest of the transmitter.

I owned a Johnson Ranger back in the mid-1970s and it was my primary 160 meter CW transmitter. Traded it off in the late 1970s. However, I do work on them for others (the last one about 9 months ago). One thing to check is the variable power resistor that sets the modulator &quot;resting&quot; current. This is adjusted by a slider that has to be loosened with a nut driver. Be sure and unplug the transmitter from the AC and short out the B+ before even thinking of adjusting this.

If you need the cable to mate with the antenna changeover relay I do manufacture these. Go to

http://k9sth.com/Page_3.html

and the link for the connectors is the 7th from the top.

Glen, K9STH

AD0IU
10-23-2007, 02:29 AM
Thanks Glen - that&#39;s good info.


Quote[/b] ]One thing to check is the variable power resistor that sets the modulator &quot;resting&quot; current. This is adjusted by a slider that has to be loosened with a nut driver. Be sure and unplug the transmitter from the AC and short out the B+ before even thinking of adjusting this.

I know the adjustable resistor of which you speak. The monstrous R35&#33; It is a resistor; it is a ceramic wonder.

I took a look at your website - very cool. I enjoyed all the pictures of your shacks, the radios you&#39;ve worked on, and the stories that went with them. I&#39;ve got a t/r for the Ranger/Allied RCVR combination that I had with my original shack - never used the changeover relay holes.

The variation in schematics has prompted me to start messing around with TinyCad to see if I can produce an accurate representation of my radio, before and after the mods. There aren&#39;t a lot of tube symbols in TinyCad, though, or rotary switches for that matter, so it looks like I&#39;ll be designing some.

73,
Rob

AD0IU
11-03-2007, 05:00 AM
Update:

1. I located a source of 2kv 16 AWG wire sold by the foot at Surplus Sales of Nebraska (HV Wire) (http://www.surplussales.com/Wire-Cable/HVWire-1.html). I got 25ft which took care of the transformer with plenty left over. The 14 AWG wire at Mendelson&#39;s that I mentioned earlier wasn&#39;t rated above 300V.

2. I found a choke at Newark Electronics (http://www.newark.com/jsp/Passives/Inductors,+Chokes+&+Coils/BOURNS/+JW+MILLER/6302-RC/displayProduct.jsp?sku=63K3908&_requestid=65987) that seemed to fit the bill.

3. I have ordered the remaining parts for the mod/rebuild from Mouser and Antique Electronic Supply. I should be surrounded by solder smoke next week. With luck, I won&#39;t be surrounded by radio smoke after I plug it in.

4. I am going to put together a &quot;grounding stick&quot;. Apparently this is a good thing to have when working on these BAs. I got zapped by a Knight T-150 around age 14 and still remember that lesson 28 years later. Has anyone here made one of these &quot;sticks&quot;? I&#39;m considering using a wooden dowel rod, a metal hook, some of the left-over 2kV 16 AWG wire and an alligator-like clamp.

I am also thinking about plugging in the transformer and (carefully) checking the voltages on the secondaries just to make sure I&#39;ve got the leads correctly identified before putting it back on the chassis. Good plan?

Rob

WA7KKP
11-07-2007, 08:39 PM
Any garden variety RF choke may not work well in the final output circuit . . .

If you pay attention to most radios, you may see the RF choke with several windings, sometimes wound in a flat pie section, with several sections being the norm.

This is due to capacity between the turns, which becomes appreciable at the higher frequencies, and effectively turns the choke into an RF short. The windings, spaced out, help break up this phenomenon.

Also watch out, as all RF chokes have a &#39;series resonant&#39; point, and this has to happen outside of the ham bands. If you have resonance in one of the bands, it also behaves like an RF short, and you&#39;ll get a lot of smoke.

Gary WA7KKP

AD0IU
11-08-2007, 09:48 PM
Hello Gary -


Quote[/b] ]Also watch out, as all RF chokes have a &#39;series resonant&#39; point, and this has to happen outside of the ham bands. If you have resonance in one of the bands, it also behaves like an RF short, and you&#39;ll get a lot of smoke.

I chose one with a self-resonant frequency of 1.3 MHz, which is well away from where I&#39;ll be operating. Thanks for the tip - I&#39;ve always preferred non-smoking radios.

This one seems to have been smoldering in the past, however. As I was carrying out the mods, I noticed 3 - 33K resistors (in parallel) attached to the the plate of the clamper were blackened + debris was actually falling off of them. A .005uf ceramic disk capacitor attached to the same pin had a scorched &quot;blister&quot;. I think something bad happened to the radio before I got it back. Details are in an earlier post dated Oct. 07 2007,16:25. (http://www.qrz.com/ib-bin/ikonboard.cgi?act=ST;f=5;t=170431;hl=ka8jby) That might explain why it came back to me without the clamper or any of the audio tubes.

Here&#39;s another question:

Many of the ceramic disk capacitors in the Ranger have values specified as GMV (guaranteed minimum value), which implies a tolerance of (0,+100%). Now when I look for these online they cost ~30-60 dollars each for the values/voltages found in the Ranger&#33; I read that the GMV types are used when the actual value of the capacitor is not critical, as long as it stays above the GMV. So, can I use some typical +/-10% or 20% capacitors and just ensure that the value when 10 or 20% is subtracted is above the GMV and keep the capacitance relatively close to the specified value?

73,
Rob

K9STH
11-08-2007, 10:04 PM
You can use the +/- 20 percent disk ceramic capacitors that are available from Mouser without any problems. I use them all the time in boat anchor equipment that I work on for others.

Glen, K9STH

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