MARITIME RADIO HISTORICAL SOCIETY |
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1 October 2022
MRHS Newsletter No. 89
Dedicated to the True Believers Worldwide
Henry Transmitter Repairs
RCA Lifeboat Sets
K6KPH Henrys
RBN
Eimac Book Free Download
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Recently we had a failure in a Henry 5000-D transmitter used in RTTY service for KPH. Pictured is an example ( not the tube that failed) of the 3-500Z Power Triode used in the IPA section. Arcing inside caused damage in the preamp section that feeds the IPA. Normally when these tubes go bad they go soft and the output drops off. Upgrades to the Henrys are being discussed for Fault Protection. Click here for Eimac Application Bulletin #17.
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A few newsletters back we showed the bad results from the non-branded MRF-433 Power Transistors with the purple top. Since then some Motorola replacements from China have been obtained and some curve tracing has been done so repairs are not made with substandard parts. On the left is a NOS part with a date code of 9350 and the one on the right recently purchased with a date code of 0417. These are for the power output in the pre-amp. |
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A trace for the NOS Motorola on the left with HFE results being the same as with a transistor tester. |
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Suprisingly the newer Chinese Motorola Branded transistors show twice as much gain! Kevin McGrath (KM) will be making repairs to a pre-amp and testing soon. |
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If you would like to help support this work and/or you enjoy using the KiwiSDR receivers you can use the link below to donate through PayPal or send your gift to:
MRHS
PO BOX 392
Point Reyes Station, CA 94956
The MRHS is a registered 501(c)3 non-profit organization, so your gifts are tax deductible. Our Tax ID Number is: 20-1122405.
Thank you in advance for your continued support. We are committed to using your gifts responsibly to help preserve our maritime and communications heritage!
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RCA LIFEBOAT SETS SAVE 84 |
Crew from SS Stag Hound, Using Combination Radio Telegraph-Telephone Units After Ship Is Torpedoed in South Atlantic Is Rescued.
Here is a story from the July 1943 Edition of RCA Magazine "Radio Age".
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Radio's vital war-time role of saving life at sea is sharply emphasized in the story of 84 men who recently returned to New York after their ship, the SS Stag Hound of the United States Lines, was torpedoed and sunk off the coast of South America. Adrift several hundred miles at sea in two lifeboats, which lost sight of each other, the Star/ Hound crew maintained voice communication by radiotelephone, and contacted four potential rescue vessels in the two days that elapsed before they were picked up. Both the Stag Hound's Captain, Harold H. McCaw, and radio operator, Edward F. Wall, credited the lifeboat's special radio equipment a combination radiotelegraph-telephone unit, powered by handcranked generator with effecting their rescue. The story was revealed in a letter G. F. Ravenel, Vice President of the United States Lines, owners of the Stag Hound, wrote to Charles .J. Pannill, President of the Radiomarine Corporation of America which built and installed the lifeboat radio apparatus. "I think you will be interested in knowing that the Captain and the entire crew of one ship that was torpedoed arrived in New York today." said Mr. Ravenel. "The Captain reports that the radio sets performed perfectly. They were able to establish telephone communication between two lifeboats which were so far separated that they were out of sight even in the daytime. They contacted by use of Morse code four ships, giving their position. These ships decided amongst themselves which one was nearest and which should effect the rescue. This was accomplished two days later, but in the meanwhile the lifeboats were able to give their exact position every four hours. "On the whole, the performance could not have been better, and it is Captain McCaw's opinion that these radio sets may very well have been the means of saving the lives of all men in both lifeboats. We desire to thank you for this contribution to the saving of life at sea during these times." Wall, the radio operator, who served in the Navy on a destroyer in World War I. also was high in his commendation of the lifeboat radio equipment. He added: "Too much praise cannot be given the simplicity and efficiency of the type set we had in the two lifeboats. The beauty of these sets is that they can be worked by telephone or telegraph so that in case the operator is missing or injured anyone in the lifeboat can work the set. Another feature—no batteries have to be bothered with, and naturally the set could be used day after day without its source of power being reduced."
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Radiomarine employees simulate Emergency conditions in demonstrating Lifeboat set, a combination Radio Telegraph-Telephone unit. |
A later model Lifeboat Set MRHS has on display at RS (Point Reyes), Radiomarine model ET-8053 from the early 1950s. |
Henry Transmitters for K6KPH |
Newsletter Subscribers have asked what we do to change frequencies when we operate the ARRL West Coast Code Proficiency runs on K6KPH. Basically a flip of the switch. These Henry Transmitters do not have a VFO and operate on one frequency. The thin section is the solid state exciter with some having 2 channels. In the case of 40 meters we operate on 7050 kcs and when the time to change over to the ARRL frequency of 7047.5 kcs the switch is moved to channel #1. The same goes for the other frequencies we transmit the Code runs on. Another question asked is how much power we run. This is a 5000 watt transmitter but by FCC rules that govern the amateur bands we can run a maximum of 1500 watts. RB/K6AAQ
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For you that are not familiar with the reverse Beacon Network, Skimmers worldwide pick up your callsign when you send a CQ. Pictured above is a small slice of where K6KPH was heard on Saturday 17 September 2022. Canary Islands, Costa Rica, Uruguay, New Zealand, Samoa, Hawaii, Japan and the Cayman Islands are just some of the places the CQs of K6KPH were heard and documented. |
A book that I have in my Library, 5th Edition from 2003 is still available at reasonable prices but if you would like a free download (1967 version) , copy and paste this address in your Browser:
https://www.qsl.net/ea2ra/Links/Eimac/C&F1Web.pdf
Whether you work on equipment that uses these tubes or just like to have reference material, you can always find something useful in these publications. RB/K6AAQ
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And don't miss our fabulous MRHS Swag store. Your purchases also provide some much needed income to the MRHS. To access these treasures, click on the picture of our lovely MRHS Model, Tina Shinn/TS, below! |
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When visiting KPH be sure to tune in to KWMR for
the great music,
local knowledge and,
most important, emergency information.
For more information about KWMR, and to listen to the live stream, click here.
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