Re capping the Johnson Ranger... again and the ORIGINAL KEYER CIRCUIT FOUND!

[W4AMV]

First, please find attached the Johnson Ranger original keyer circuit and instructions. This data issued for the Ranger "0" as the conversion from cathode to grid block keyer. My thanks to Jeff in Mass. after an ebay conversation! And next a question on re-capping. Other than the obvious caps to replace... what are the "destroyer caps" ? By this I mean, if that cap goes, heaven have mercy on you! I have replaced the LV and HV caps, however, nothing else. I have been slowly bringing the Ranger up on variac as I troubleshoot and was just about there 2 evening ago... when POW, a .005 uF 630 V line filter cap went. This cap takes 110 V to ground and the 5 A fuse blows. Lots of FUN to watch but not to experience. What is interesting about this event, is when I first got the Ranger, the 5 A line fuse WAS BLOWN. However, I HAD NO IDEA WHY. I measured every node I could with not a hint as to why this fuse blew. However, I DID NOTE this ceramic cap looked a little strange, as there was a mouse bite out of the head of the ceramic, very small. I did not give it a second thought! Well, when the POW went, guess what. It was THIS cap. BUT, there was no obvious pointer that it was this cap!!! Until you look very carefully at the chassis and note a black "soot" trace along the side of the chassis up to and stop at this CAP. For all intents and purpose, the cap looks perfect!! So... again, which are the destroyer caps? I dont want to re cap the whole radio. And I dont mind a POW! But I hate to loose a tough part to replace!

Thanks, Alan
W4AMV

[KC2ZFA]

methinks any cap between hv and ground is potentially a party pooper cap 

Peter

[WQ9E]

Alan,

First, thanks for posting the keyer information.  I will soon be going through another Ranger that does not have the keyer circuit.

Caps I generally replace are all electrolytic caps in older gear; don't miss the smaller bias caps and cathode bypass caps.  I also replace grid coupling caps feeding any high power audio stage, leakage here can take out tubes, transformers, etc.  Any of the old wax paper or black beauty types are also replaced.  Finally, older type line bypass caps get replaced; use modern line rated replacements here. 

Are you using the original fuse type plug or has it been replaced by a 3 wire cord?  With 3 wire systems I put the line bypass cap on the rig side of the line fuse (which should be in the hot/"load" lead).

Rodger

[W4AMV]

Hi Rodger. You are welcome on the keyer documentation.

Yes, I am still using the 2 wire plug with the 3 and 5 amp in line fuses. I ground the rig chassis to the line neutral which right now is the variac. I agree, I need to convert this 2-wire plug. In any case, HOORAY, the Ranger is up and running and I'll check Pout next. Plate current at 500 V (key up), and ~ 450 V (key down) is 130 mA. My line V at this test was 100 V. Still being conservative! Ok on the caps. I had a question on prior thread.

Is the removal of SW5 straight forward? I have the meter SW working as explained earlier, but I would really like to do the clip properly. So, if I remove only the knob, front panel bolt and the chassis hardware that fastens the right angle bracket to the switch, is that sufficient?

Alan

[W4AMV]

Peter, Rodger, I guess what I was going to try and do, is review the schematic and figure which caps, if they were to short would cause fatal damage. In other words, for example, if I had a 0.1 uF operating as a bypass of a 1 k resistor at 500 V and it shorts, I might take out the R. Particularly if the R would not support the dissipation power under that condition. Well, a 1 k R is not a major loss, however, if this were a RF coil wound with fine Litz wire, it may be a whole different story.  Does this make sense? So, as time permits, put together a simple SS that points to the "critical" components and bounce it around.

[WQ9E]

Alan,

I have never had to remove that switch from my Ranger but your description sounds logical.  Probably the biggest concern will be unsoldering the wires without damage to the switch or wiring.  Hopefully the builder simply put the leads through the terminals rather than wrapping them which makes removal without damage difficult.  Keep in mind that excessive heat may change the tension characteristics of the switch contacts.

[WQ9E]

Alan,

I do consulting and research in quality and risk management but I have never formally applied tools from these fields it to vintage gear component failure and resulting collateral damage.   My philosophy is to replace components with a known very high failure rate (old electrolytic caps, old line bypass caps, the classic wax dipped paper caps, and "black beauty and bumblebee" caps).  I also replace some fairly high reliability components where failure would cause obvious expensive collateral damage (i.e. grid coupling cap to the output tube).  But I don't take it down to the "what else will be damaged if the .01 disc Cxx fails shorted"  since if you are going to play this scenario you are often looking at a long string of potential interrelated failures (i.e. load loss on one supply causes another supply voltage to soar causing additional component failure leading to additional sets of failure likelihood etc.).  I just do not think this is worthwhile since most vintage parts are replaceable or even rebuildable without too much difficult.  I look at this from the risk management view that the cost of mediating the risk exceeds the expected payoff in most cases.

It might be an interesting intellectual exercise if one had A LOT of time available.  I have so many pieces of vintage gear that it isn't practical for me to engage in this level of analysis but it will be interesting to learn what others think about this form of potential damage management.

[W4AMV]

Hi Rodger. I agree. It seems like a bit of work and if you have multiple vintage gear, a real pain. However, I might do it on this Ranger, only because I have in hand a limited number of replacement caps and I would like to a least minimize my risk before placing this rig into service. On the other hand, I can go it slow like the other old gear I have, and eventually place it on the air ( seems like it takes for ever). In any case, thanks again for the feedback.

[KA2DZT]

First, please find attached the Johnson Ranger original keyer circuit and instructions. This data issued for the Ranger "0" as the conversion from cathode to grid block keyer. My thanks to Jeff in Mass. after an ebay conversation! And next a question on re-capping. Other than the obvious caps to replace... what are the "destroyer caps" ? By this I mean, if that cap goes, heaven have mercy on you! I have replaced the LV and HV caps, however, nothing else. I have been slowly bringing the Ranger up on variac as I troubleshoot and was just about there 2 evening ago... when POW, a .005 uF 630 V line filter cap went. This cap takes 110 V to ground and the 5 A fuse blows. Lots of FUN to watch but not to experience. What is interesting about this event, is when I first got the Ranger, the 5 A line fuse WAS BLOWN. However, I HAD NO IDEA WHY. I measured every node I could with not a hint as to why this fuse blew. However, I DID NOTE this ceramic cap looked a little strange, as there was a mouse bite out of the head of the ceramic, very small. I did not give it a second thought! Well, when the POW went, guess what. It was THIS cap. BUT, there was no obvious pointer that it was this cap!!! Until you look very carefully at the chassis and note a black "soot" trace along the side of the chassis up to and stop at this CAP. For all intents and purpose, the cap looks perfect!! So... again, which are the destroyer caps? I dont want to re cap the whole radio. And I dont mind a POW! But I hate to loose a tough part to replace!

Thanks, Alan
W4AMV

630V line filter?  I'm thinking this part is not original to the set.  Back when Rangers were made, I don't think they made parts with 630V ratings.  Maybe I'm wrong, but it may not hurt to check the manual and find out if that part is correct for the purpose it's being used for, or if it should be there in the first place.

In more than 50 years of working with this old stuff, I don't think I've seen more than a few bad ceramic caps.  On the other hand, I've seen a lot of blown ceramic caps in TV-antenna-system amplifiers that were tagged by lightning.

Fred

[W4AMV]

Hi Fred. I refer to them as line filters, however, it is the Johnson design of L-C networks like C61a, C61b, L25a etc... that are locally placed TVI filters. They are composed of 600 WV ceramic disc C's and the associated spring inductor. In my case, C61a, C63b, that were at risk. C61a provided the fire works. I replaced with 630WV film caps.

Alan

[WQ9E]

Alan,

Although your working voltage is normally sufficient, service across the AC line places special stress on the capacitor thus there are capacitors specifically designed for this service.  See for example:  http://www.mouser.com/ProductDetail/Panasonic/ECQ-U2A123ML/?qs=sGAEpiMZZMvQAn3cSZoTr%2fBcW2olj7gBrI50HQIdgKI%3d

and take a look at the data sheet.

[W4AMV]

Rodger, thanks for the heads up and good point. I thought about that, and for a few extra pennies, it is worthwhile to put in "safety rated" type.