Dedicated to True Believers World Wide 
2 October 2012   




12, 13, 14 October 

Santa Clara, California

The MRHS attended Pacificon 2011 and we had a great time.  We set up two operating positions using vintage gear, remotely keying the KSM and K6KPH transmitters in Bolinas while receiving on heavyweight gear at Pacificon. 
MRHS operating position at Pacificon 2011 for KSM showing, L to R, Underwood mill, RCA AR088LF receiver with National SW-3 Thrill Box atop, transmitter control console with radio room clock atop, Marconi Atalanta receiver and Boehme keying head sending the KSM "wheel" 
Now the organizers for Pacificon 2012 have done us the honor of asking us to return which we are most happy to do.  We anticipate essentially the same setup as at 2011 with operating positions for KSM and K6KPH.
Dave Wolfe (ex-WCC) at the K6KPH operating position using a HRO-5A receiver and keying the 1.5kW transmitter in Bolinas
Will you be attending Pacificon 2012?  If so please stop by our exhibit.  We look forward to meeting as many True Believers as possible.  If you have a commercial radiotelegraph ticket you can sit the circuit at KSM.  Or you can operate K6KPH. Either way we hope to see you there.  
Remember, it's also the ARRL National Convention!
Oh, and by the way, MRHS T shirts will be on sale.  These have a MRHS logo on the front and "160HA1A" on the back which, as all True Believers know, is the emission designator for manual Morse.
Ms. Tina Shinn wearing the MRHS T shirt
For further information including directions, hotel reservations and events please go to the Pacificicon 2012 Web site.
See you there!

Remote Control by Tone Set - A History


By William F. Ruck, MRHS Maintenance 


Part II of a three part series...


After Newsletter No. 17 hit the streets with the first installment of Bill Ruck's compelling history of transmitter remote control by tone set Bill wrote to say it's actually a three part series.  So we have an additional episode of tone set passion and drama to look forward to, torn from the flaming pages of obscure technical manuals.


When we last left Bill in episode one he had brought us up to the tube version of audio frequency shift keyers.  Let's listen now as we hear Bill say...


The first part of this series explained why communications is best with separate transmitter and receiver locations and how the transmitters could be remotely controlled.  This article goes into detail on the tone sets used by KPH and now KSM.


Background - 


In 1959 when RCA built new Building 2A in Bolinas and equipped it with new transmitters they also built a new control room.  The new control room was equipped with the latest state-of-the-art equipment including RCA Model 901 and 902 Frequency Shift Tone Transmitters and Receivers.  These were clearly advanced for the day as they were solid state - germanium transistors.


It is curious to note that the RCA Model 901 F/S Tone Transmitter and the RCA Model 902 F/S Tone Receiver were actually manufactured by Tele-Signal Corporation in Hicksville, New York.  This was not uncommon for RCA.  Their corporate philosophy was, in summary, "If it is not sold by RCA you don't need it."  In many instances specialty items such as these tone sets and test equipment was manufactured by others under contract and was delivered in RCA standard colors with an RCA logo on the front panel.  (The traditional round RCA logo is commonly known as a "meatball".)


Rack of 902 receiving tone sets (and one 901 set) in the control room at Bolinas


The Radio Corporation of America Model 901 Frequency Shift Tone Transmitter and Model 902 Frequency Shift Receiver is a completely self-contained unit, including power supply and monitoring facilities.  It is mounted on a 5-1/4" by 4" panel and has a depth of approximately 10-3/4".  This structure permits mounting of up to four such transmitters or receivers in the space of one standard 5-1/4" x 19" panel.  Such groups can be stacked with other groups of such equipment.  Up to 48 channels can be readily mounted into one standard relay rack.  In such multi-channel systems all transmitters and receivers are alike: plug-in type frequency determining networks and channel filters determine the channel frequency, frequency shift, and channel speed assigned to each unit.


Although all of the 901 F/S Tone Transmitters and 902 T/S Tone Receivers have identical circuitry, the bandpass filters are designed for a specific frequency and are not interchangeable.  There are plans for center frequencies with standard networks.  One plan is shown below.


Table of frequency determining networks


The packaging of the units has been made with regard for ease of maintenance.  All small components are mounted on one single "card", on the reverse side of which the wiring is printerized.  This "card" is readily tilted out of the unit, giving complete access to all parts.  Test points are available directly on the front panel and permit monitoring and alignment of the unit without removing it from the rack.  Frequency adjustments, such as center frequency, mark and space frequency adjustments, though an integral part of the plug-in network, are accessible from the front panel.


Tone set circuit board showing germanium transistors


For the point-to-point service RCA equipped the San Francisco office with type 901 F/S Tone Transmitters which connected via their dedicated telephone circuits to Type 902 F/S Tone Receivers in the Building 2A control room Rack 2.  There the low level keying was patched to banks of Type 901 F/S Tone Transmitters.  The audio output of those f/s transmitters was used to modulate the radio transmitters in Building 2A and Building 2 used in the point-to-point service.


For KPH, the maritime service, Type 901 F/S Tone Transmitters were installed at Point Reyes and fed the dedicated telephone lines to Bolinas where a bank of Type 902 F/S Receivers in Rack 3 decoded the audio and keyed KPH transmitters in Building 1 and Building 2.


When the point-to-point RCA Global Service was discontinued after the satellite transition the 901 and 902 tone sets used by KPH continued to serve the station as the newer point-to-point transmitters in Building 2A were converted to Morse operation and connected to the 902 f/s receiving tone sets from Point Reyes.  Today the same 901 and 902 tone sets continue in service to key the KSM transmitters in the same way as they have been used for more than 40 years.


These tone sets have demonstrated excellent reliability.  About the only problems that we have with them is replacement of power supply electrolytic capacitors.  Anyone using vintage equipment recognizes that these capacitors do not last forever and whenever we find one tone set to be erratic the first thing we do is to replace the old power supply capacitors.  We know from bitter experience that old C/D and Mallory capacitors with paper tube outer jackets are long past their expected life. 


Other than that every once in a while we have to swap out erratic tone sets and align them.  RCA left us with a test jig that allows the 901 transmitter and 902 receiver to be connected back-to-back.  In short order they are realigned and ready to be put back into service.


Jig for test and alignment of 901 and 902 tone sets and for the 909 switch (seen in background, behind the jig) 


We did learn during the restoration of the teletype order wire that 901/902 alignment is much more critical in the teletype service than in the Morse service.  We've learned how to quickly align them with a 50% duty cycle square wave at teletype speed.


RCA Model 901 F/S Tone Transmitter System Description -


Refer to Figure 4, F/S Tone Transmitter Block Diagram.




A series tuned circuit, consisting of C1 and L is driven by two states of impedance stepdown converters.  At resonance the voltage across L is 90 degrees with respect to the voltage across the tuned circuit.  The voltage across L drives a phase splitter which in turn feeds a series RC circuit consisting of C2 and R1 as long as the Keying Transistor is cut off.  Varying R1 permits changing the phase angle from nearly zero to almost 180 degrees with out any changes of amplitude.


With R1 adjusted to a resistance equal to the reactance of C2 (at center frequency of the tank circuit) the voltage at the junction of C2 and R1 is 90 degrees and the phase fed back to the impedance converter is correct for regeneration, causing the circuit to oscillate at center frequency.


Increasing R1 causes the phase angle to differ from 90 degrees and the circuit will oscillate at a lower frequency of which the phases will again be correct for regeneration.  Application of sufficient current to the Keying Transistor to saturate the base will effectively shunt R2 across R1, lowering the resistance which in turn causes the circuit to oscillate at a higher frequency.


At correct adjustments of R1 and R2, the Mark and Space frequencies will result from equidistant phase departure from 90 degrees at the tank circuit.


The output is coupled out through a stage of amplification and a bandpass filter.


The circuitry of the 901 F/S Tone Transmitter is well though out because the same unit can be used in different keying schemes.  The units are all the same and the different modes are determined by how the rack connector is wired.  The 901 F/S Tone Transmitter can be wired as follows:


1.  Contact Keying.  Used at KPH (now KSM) for Morse.


2.  Current Keying with external 60 mA line battery.  Used for teletype.


3.  Current Keying with self contained line battery using Line Battery Model 914 accessory.


4.  C.W. Tone Keying with C.W. Tone Demodulator 904 accessory.


5.  Voltage Keying into 2,200 Ohms.


6.  Voltage Keying into 100,000 Ohms using Voltage Keying Adaptor Model 905 accessory.


RCA Model 902 F/S Tone Receiver System Description - 


Refer to Figure 3.  F/S Tone Receiver Block Diagram




The incoming frequency shift signal is fed through a bandpass filter and a pre-amplifier to a push-pull limiter.  The square waves from this limiter are fed to the polar detector.  Simultaneously, through a resistive divider accomplishing both attenuation and impedance stepdown, the square waves are fed to a series tuned circuit tuned to center frequency.


The voltage across L is fed through a limiter to the polar detector.


The polar detector is essentially a phase discriminator, the voltage output of which depends on the relative phase of the square waves coming from the push-pull limiter and those from the limiter after the tuned circuit.


At center frequency the tuned circuit produces a 90 degree phase shift.  At mark and space frequency phase shifts of less, and more than 90 degrees respectively occur at the tuned circuit.  The output of the polar detector feeds a simple low pass filter.  A voltage sensitive trigger driven from the low pass filter is adjusted to give unity weight to the output.


Like the 901 transmitter, all of the 902 receivers are identical except for the band pass filter.


The 902 receiver can be connected in the following ways:


1.  Current keying into a standard 65 mA 2000 Ohm loop using a Model 909 Transistor Switch accessory.


2.  Low level keying output (-7 volts into 12K or larger)


3.  C.W. Tone Output with C.W. Tone Keyer Model 906 accessory


4.  Standard Relay Output with Transistor-Relay Model 907 accessory


5.  Current keying into a single printer or loads not exceeding 250 Ohms with a Transistor-Keyer Model 908 accessory.


Most of this report was directly quoted from flaming pages of the RCA Model 901 and Model 902 manuals.


The last part of this series will explain how an individual operator at RS could select which transmitter to key.



Make a Donation

Bill will continue this thrilling story in Part III.  But you have already seen the depth of research and documentation in which we engage, all with the hope of understanding and preserving the history of the facilities that have been entrusted to our care.

To all those who have sent along a contribution to The Cause we offer a heartfelt thanks.  Your support is tremendously appreciated.

If you're a True Believer and can make a contribution to The Cause it will be most appreciated.  And remember, we're all volunteers so 100% of your contribution goes directly to purchase the items needed to keep the transmitters and receivers working and the antennas in the air.  





Operations Report


Mr. and Mrs. America and all the ships at sea... let's go to press with Mike Payne's operations report for 
KSM and K6KPH...


Wed Sept 26th, 27th GMT


Posn 1






0211 AL7N (14) NTS TFC check QRU/QRU AK

0236 YL2TQ (14) 100W Beam Aluksne, Latvia

                        Note: Long/Short path echo


0325 K7SF (3.5) 100W OR

0345 JQ1NID (21) JA

0358 RA9UH (21) RUSSIA

0400 K7EE (21) AZ Note: Sudden signal drop-out QSA 5 to QSA 0 in 0.25sec

0403 K4EZU (21) QSB to Nil

0445 XE2IF (7) CABO, MX

0520 N70G (7) UT


Posn 4






0204 K6DXU (7) Beam up 60FT

0210 W5KY (7) NM

0239 K7PKQ (7) AZ

0249 KC7YE/M (7) IOWA

0304 WQ1K (7) Los Altos

0344 KB2RAW (14) NY

0347 KF7WL (14) No QTH

0358 AL7N (14) AK

0406 W7ASA (14) VA

0428 RD3PO (14) RUSSIA

0436 IK7FPU (14) Italy

0444 LZ2RS (14) Central Bulgaria

0446 UT4UH (14) Kiev, Ukraine

0450 RA1NBV (14) RUSSIA

0451 SV1DOJ (14) Greece

0501 W8JGI (14) West VA

0511 KF5KYS (14) TX


Sat Sept 29th


Posn 1




1920 KKUI (12)




1855 AL7N (14) AK

1939 KL2AX/7 (21) QRP 10W G5RV HOMER AK

1945 W4LNI (21) KSM Sig Rpt VA

1953 UAO1DZ (21) RUSSIA

1957 G4AQG (21) Brighton at University of Sussex Home C/S G3XDK UK

2002 N3RSD (21) DE

2014 AC2C (21) Rig KX3 QRP MD

2030 W8IM (21) QTC 2 KSM Sig Rpts FLA

2047 K4KTM (21) Central NC

2124 KO6VD (21) CO

2131 K6ETM (21) KSM Sig Rpt

2144 AG4HR (14) NC

2153 W2OR (21) ME

2204 JJ1RZG (21) Downtown Tokyo WX Sunny Temp 22C Typhoon approaching

2213 WD0BC (14) Portable Battery at 10W QRP MO

2302 JS1JTX (21) 100W 4element Yagi up 15M WX Sunny Temp 26C


Posn 6




1914 KH2BR/W6 (14) CA

1919 N7EQO (14) WA


Visitors were 6


Sun Sept 30th


Posn 1






1925 W4LNI (14) KSM Sig Rpt FLA

1027 AL7N (14) NTS TFC check QRU/QRU AK


2143 K6AA (14) CA

2150 WD0BC (14) QSB'd to Nil MO

2210 JJ1RZG (21) 3ele Beam 100W Typhoon passed, all ok Tokyo JA

2222 VE7BGJ (7) Delta Port south of Vancouver, BC

2228 AE7PG (7) WA

2258 WD8KRV (21) KSM Sig Rpt AZ

2303 W8IM (21) KSM Sig Rpt FLA

2323 K6TBW (7) CA

2355 AC5P (14) OK


Visitors were 1




Many thanks to W4LNI, W8IM, K6ETM, WD8KRV, N5KY, and K5HGX for your KSM Signal Reports. They are most appreciated.


To AG4HR, Raj for hanging in there with me as your signal went to nil.


To AL7N, ED for constantly checking in with us es keeping the NTS channel open.


To KL2AX/7 in Homer, AK with his mighty 10W on a G5RV.


To K6TBW, Sandy when I told her my key had suddenly broken during QSO. You were correct, it

                     hadden't broken...operator error...again.

To AC5P, Mike who was most gracious in allowing me to try and "smoke" my bug at 30+ wpm.

     I havn't sent that fast in many a moon...way cool, but I need practice.


And a very special thanks to the guys at KKUI for continuously contacting KSM. Every time you come up we raise a cheer.


To all you former RMs who contact us...QAP INT QTC ZUT ZUT ZUT.


Right. So Panic Payne is QTH at RS on Saturday around 11:30LT es in the process of dialing up the xmtrs via the tone-sets at RS down to Bolinas via the LL when he hears no dial, no, no. the problem must be with Bolinas...give em a call on the squak box. (Bolinas checks their problem here).RD calls in es says he will shortly be at RS (He is driving up from Bolinas). Whew. .Will Panic Payne be saved? A few minutes later when RD arrives at RS he checks out the phone line and promptly fixes the problem. After the most technical fix I could just hear him thinking, "Yo...lid...ya think ya might have checked to see if the line jack was inserted into the phone?" Ok, ok, so now all is right with the world, I dial up the xmtrs and all is well. No, no, no (again), "I can't hear the KSM Wheel on any of the freqs on the monitor rcvr Kenwood R5000...I call up Bolinas again..."No problem here." Once again I turn to RD. A little history here. Every time I open up RS I due a run through of all the positions to make sure that there nothing is "on", no xmtr switch is up, no antenna selector is engaged, that all is as it should be. So what do I find at Posn 2? KPH530 antenna selector is in the select position. Naturally, I disengage it. Now back to RD, and once again a most technical fix. He engages the Posn 2 KPH530 antenna selector switch that I had recently disengaged with the result that I can now hear the Wheel on the Kenwood R5000 on all KSM frequencies; and once again I can hear him thinking, " you think you might have read the sign under the switch that read - Do Not Turn Off. Antenna selector for KSM Wheel Kenwood R5000, Posn 1" Dum dum ditty dum dum...again. So how long have I been volunteering at RS?...over a year.

73s fm ZUT central, MP





QRX:  Wednesday night, Sept 26th, 7pm to 11pm local time.  MP and FW on watch at KSM and K6KPH.


As always, if I have listed your c/s incorrectly or neglected to list your c/s please let me know and I will make the correction in a following newsletter.  73s from zut central.  MP



VY 73, 

MRHS Operating Department 

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

VY 73,


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