MRHS NEWSLETTER No. 30 
Dedicated to True Believers World Wide 
12 March 2013
 

Headlines 
  • An Inquiry from the Editor
  • Restoration Update - Transmitter 298
  • Bill Ruck's Titanic Battle Continues
  • FLASH! Marconi Trans-Pacific Transmitter Opens for Service
  • Operations Report - Changes to Note - International Marconi Day 

 

An Inquiry From The Editor  

 

From time to time we like to check in with Newsletter readers to confirm that we're on the right track with the articles we include.  For example in this issue there are two articles - the transmitter 298 restoration update and the report on Bill's continuing battle with the WCC control panel - that are pretty technical.  But we're been told that's the kind of thing True Believers like.  True?  Yes or no, we'd like to hear from you.  Just QSP to info@radiomarine.org .  Thanks!


Restoration Update - Transmitter 298

Readers of these pages will doubtless recall our restoration project aimed at bringing H set transmitter No. 298 back to life.  The initial report was in Newsletter No. 10.  New readers would be well advised to view that issue for the astounding before and after photos if nothing else.  Updates were presented in Newsletter No. 11 and Newsletter No. 14.

Now comes Mr. Bob Dildine of the H Set Crew with a report on the latest work that took place on Saturday 2 March:

March 2 was another productive day at Bolinas for Greg Farrell, Tom Harris, and Bob Dildine. We started with Greg installing the dual RF ammeter on the H-set using the bracket that Kurk Radford fabricated, while Tom and Bob installed new grounding convenience outlets on the front and back of the transmitter cabinet. Tom and Greg also re-connected the interlocks on the cabinet's rear door and Tom fixed the big red light on the back of the transmitter.

Dual RF ammeters atop filter assembly atop H set transmitter No. 298.  The green cloth covers the air exhaust to keep heat within the transmitter between oprtations. 

Then Bob installed an AC coupled test point on the PA screen supply. This consisted of a .022 uF capacitor in series with the screen supply output and shunted to ground with 200k tapped at 20k to give a 10:1 voltage divider. The objective was to measure the AC ripple on the screen supply to see if that is a cause of the raspy note on the transmitter.

PA screen supply test point 

The transmitter was fired up and the measurement made: 200 volts peak to peak ripple at 60 Hz! (Not 120 Hz as would be expected with a faulty filter capacitor.) No wonder the transmitter's note sounds bad.

544B showing 60Hz ripple.  Vertical scale is 200V/division., horizontal is 5msc/division. 

Just to make sure, we also measured the ripple on the PA grid bias supply and found it to be quite clean. We put the spectrum analyzer (an HP 8553B) on the transmitter's output and took a careful look at the spectrum close in. The driver (4CX250's) alone was clean with no line related spurs down to at least -70 dBc. When we turned on the PA (the 4CX500A's), its output had 60 Hz spurs at about -20 dBc which was consistent with the envelope we saw on an oscilloscope.

Transmitter No. 298's output as seen on the spectrum analyzer. 

The conclusion is that there's a problem with the screen supply. We didn't have time to do any more trouble-shooting, but the 60 Hz ripple indicates AC probably getting into the regulator. Or it could be one of the solid state rectifiers has gone completely open and the supply is only working on a half-wave rectifier. One cause of AC getting into the regulator would be a heater-cathode short in the 6146 amplifier tube in the regulator circuit. (But the schematic shows the heater and cathode connected together.) All this is speculation of course until further trouble-shooting can be done next time out. We have a spare, newly rebuilt screen supply that can be swapped in.

While looking at the transmitter's output on the spectrum analyzer we noticed the backwave (the signal present when the transmitter is un-keyed) varied between greater than 70 dB and only 50 dB below full output. It should always be greater than 70 dB below full output. When the backwave was high, it could be varied by turning the RF Input Level control on the Linear Amplifier which indicates the problem is further back in the exciter chain. This is a newly observed problem and needs further investigation.

Next time we'll try some simple experiments on the screen supply like replacing the 6146 and the rectifiers. Then we may swap screen supplies.

That's it for this time.

Bob Dildine

If there was ever any question - and we're sure there wasn't - about the quality of technical expertise that Bob and the rest of the H set crew bring to the restoration project this report should put them to rest.

As we draw closer to the day when the "money button" on H set 298 is pressed the excitement grows.  But still, every step toward that goal is taken with care and with full documentation.

If your budget permits you to make a donation to help support The Cause it will be deeply appreciated.  And it's easy.  Just click on the button below.

 
Make a Donation 
 
Thanks!


 

 

Maintenance Report - Bill Ruck's Titanic Battle with the WCC Keying Panel Continues 

Fear for Bill's Well Being Continues to Grow 

 

Faithful readers will recall that in the previous issue, Newsletter No. 29, Bill Ruck of the MRHS Maintenance Department reported on his battle with the WCC keying panel at the receive site.  When we last left Bill he was dealing with the great frustration that derives from incomplete documentation or, worse, documentation that's not correct.  As you will see, this situation is taking its toll on the great man, causing him to hear voices and mutter to himself.   But in spite of all he perseveres. 

 

Let's listen now as we hear Bill say... 


The plan was to check the system and install a new cable so that the WCC keying lines could be connected to the RCA 901 tone sets. I set up but could not get it to work. Much testing later I gave up, asked MP to step aside and removed the CW Position 1 WCC panel.

On the bench it worked perfectly. But back in the room I could only get intermittent keying. Grumble.

Rather than continue to annoy MP I pulled the panel out at Position 2 and started testing. I could get some lines to key some of the time. Grumble. Mutter.

Back and forth between the blue WCC rack and Position 2. Grumble. Mutter.

MP likely was contemplating how to get ahold of the guys with the big butterfly nets and jacket with very long sleeves. Then the voice in my head said "MEASURE THE VOLTAGE ON THE LED / RELAY BUSS." "It's just 5 V." "DON'T ARGUE WITH ME" Grumble.

I went back to the shop and got my trusty VOM. The voltage was 3 VDC. "But there is nothing between the +5VDC power and there except a switch contact." "MEASURE THE VOLTAGE AT THE POWER SUPPLY PIN". Also 3 VDC. "But there is nothing between there and the +5 VDC power supply other than a long piece of wire." "STOP ARGUING WITH ME AND MEASURE THE POWER SUPPLY". I went back to the WCC rack, removed the power distribution panel and disassembled it enough to get to the power supply. Ah-hah! It was only making 3 VDC.

The grain-of-wheat bulb in my head started to glow. Dimly. Went back to the shop, got the bench supply that I had been using that had a +5VDC output and wired it to the power wires. Now all WCC lines keyed properly. The 3 VDC was enough to get the LEDs to light but not enough to reliably pull in the relays that switched the keying lines from the wheel to hand keying.

Bill is willing to do just about anything for The Cause.  Here we see him descending into a cable vault filled with what we call "rat soup" due to the dead, floating vermin it contains. 

Also noted that with really 5 VDC the LEDs in the WCC panels are much brighter than they were before. Duh-oh!

By then it was late enough that it was time to clean up, so I did not get a chance to move forward. The Acopian 5EB200 "AC to DC POWER MODULE" is a pretty solid lump. My experience in the past is that these are potted and can not be repaired. A +5 VDC supply at 600 mA (I measured the current with all 10 lines selected at +5 VDC) is not hard to make; all I need is a 7805.

Will check Ye Olde Junque Boxe and see what I can find to make a replacement that may fit into the power distribution panel. Oh, by the way, the wiring on that panel does not resemble the schematic. Welcome to KPH  

 

RK  

 

This is the sort of thing that drives grown men mad.  We figure we'll be able to squeeze a little more work out of RK before we have to ship him off the the Old Radioman's Home where he can rest comfortably and his mutterings will be deadened by the padding on the walls of his room.

 

No, but seriously, who among us has ever wielded the probes of a Simpson 260 and not run into such frustration?  Right, we've all been there.  The difference is Bill simply...  will... not... give... up.  And that's really what it takes, combined with some really top drawer technical chops, to keep The Project moving forward.  

 

If you've been following these reports of our activities you know that all of us, including Bill, are volunteers.  And Bill, yet to retire, is trying to make a living in between sorting out the arcane systems of KPH.  He makes the trip from San Francisco to remote West Marin and even brings morning buns along to be consumed at morning Services of the Church of the Continuous Wave at Bolinas.  It's really hard to ask for more than that.

 

Of course we all participate happily in this project and feel lucky to be involved with The Cause.  But you know... a little assistance from our fellow True Believers would be a great help.  It allows us to make purchases of needed parts and equipment that otherwise would have to be paid for from our personal bank accounts - which we are happy to do when needed.  

   

 

Make a Donation 
 
Are you in a position to help The Cause with a donation?  Even the smallest amount helps.  And it lets us know that the project means a lot to other folks, not just to ourselves. 

Thanks!

 

FLASH!  1914 Opening of Bolinas Trans-Pacific Station

As most readers know, the Bolinas transmitting station and Point Reyes receive station are both on National Park Service land, part of the Point Reyes National Seashore.  This fact was critical to the preservation of the stations.  If they had not been on Park Service land they would have been bulldozed before the tubes grew cold after the last transmission, just like all the rest of the great coast stations.

 

Ms. Carola DeRooy 

Another wonderful thing about being part of the Point Reyes National Seashore is working with the parks Archivists.  Headed by Carola DeRooy, they have gathered preserved and indexed thousands of papers and artifacts that otherwise have been lost.  And they're great folks too, with a real interest in our project.

The other day Greg Farrell of the H set restoration crew asked whether there was an opening ceremony on "day one" of trans-Pacific operations when the Marconi 230kW rotary spark gap transmitter at Bolinas went on the air for the first time in revenue service.  Carola lost no time in producing a copy of the San Francisco Chronicle for 25 September 1914 with the story of the station's opening.  That kind of service and support is pretty hard to beat.



Please click HERE to view a copy of the actual article

It's a little hard to read but worth the effort.  Here's a first hand report on the great impression of power made by the rotary and it's musical note.  The text of the first official messages is included. 

Not included is the story we have heard - and always hoped was true - that during the ceremonies the feed through insulator in the wall of the building exploded and had to be cleared by workmen with sledge hammers before transmissions could resume.  We secretly believe it actually happened but that the story was suppressed so the reputation of American Marconi Company and its engineers would not be tarnished!



Operations Report - Note Changes 

 

  • KSM Phone: +1 415-669-9646  -  Give us a call to give signal reports, coordinate schedules or just chat.  The phone will be answered whenever an operator is on duty, typically after 1200 Pacific time on Saturdays.
  •  Operating Hours - We regret to report that Mike Payne is unable to continue with his heroic schedule as a KSM/K6KPH operator.  It will be recalled that because of Mike's enthusiasm we were able to expand our operating hours to include Sundays and Wednesdays.  Unless and until more Morse operators step up for duty (see below) we will revert to our previous operating hours, viz:

Saturdays from 1000 Pacific time  (1700Z with Daylight Savings Time in effect) to 1600 Pacific time (2300Z).  Note that KSM auto keyed Morse press and weather begins at 1700Z while KSM RTTY press and weather begins at 1800Z).  Manual KSM and K6KPH operations begin at 1900Z.   

  

  • Morse Operators Needed - Are you ready to step up and grasp the throttles of a real commercial coast station?  Yep, that could be you wearing the MRHS earphones and green eye shade.  All that's required is a basic competency in Continental Morse and a willingness to show up at least twice a month.  No commercial ticket?  No worries.  You'll sit the circuit at K6KPH until you're ready to take the exam for your commercial radiotelegraph license.  All coaching will be provided if needed.  Such a deal.  Interested?  Just send a message to info@radiomarine.org and we'll go from there.
  • International Marconi Day - As all True Believers know the birthday of the founder of it all is in April.  Each year the Cornish Amateur Radio Club sponsors International Marconi Day in which amateur stations come on the air to contact Award Stations, those with a lineage leading back to a historic Marconi station.  With transmitters at the original Marconi site in Bolinas K6KPH certainly meets that test!  K6KPH has participated in the IMD event for the past several years and we plan to do so again this year.  The date is 20 April.  More information about K6KPH operations will be forthcoming but at this point we just want to alert readers of the event so they can save the date.  And of course if you want to be a K6KPH operator on this date (some have already volunteered!) just let us know by writing to info@radiomarine.org. 

  

 


MRHS Merchandise!

T shirts, hoodies, mugs, belt buckles, bumper stickers - we've got them all for you at the MRHS on line store - each with the MRHS logo.

These are high quality items you'll use and enjoy for a long time.  And every purchase you make helps to support the MRHS.

Click on the image below or on the link below that to go to the MRHS True Believers on line store.


 


Until next time we wish you fair winds and following seas.                      

VY 73,
MRHS



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