FOR SALE – Signal Corp Wireless Set No. 19 MK II

1942 WWII US Military Wireless Set No. 19 MK II

$299

very rare mobile communication unit, WW2 era, 1942, sender-receiver with power supply. I also have a canvas cover that I ~think~ goes with it, so you get that also. Unit is large/heavy, estimate 100-lbs. Dimensions approx 27 × 10 × 13.25in.

This unit has the multi-language English / Russian Cyrillic front panel lettering, so that soldiers from either USA/UK or Russia could operate the unit. Very collectible.

Untested, sold AS IS, AS FOUND.

$299 + ship or prefer you pickup.  You can estimate your own shipping costs at 100-lbs, suitably large size box, from my zip 15063 to your zip.

—————————–

Info from Wikipedia:
“The Wireless Set No. 19 was developed in 1940 by the British War Office’s Signals Experimental Establishment and by Pye Radio. The Pye model was replaced with the MK II model in 1941, and the MK III model in 1942. The sets proved valuable for armoured fighting in the Western Desert.

In 1942, the No. 19 Mk II was produced in Canada by Northern Electric Co., Canadian Marconi Co. and RCA Victor. The British design was improved and interchangeability of components such as the valves, was instituted.[3] A majority of Canadian sets used English/Cyrillic front panel lettering, the result of a Lend-Lease contract to the Soviet Red Army.[4]

Post-war, forward area battle group radio traffic carried by Wireless Set No. 19 nets was progressively migrated to low-band VHF using a more modern generation of radios known as the New Range, later to become known as Larkspur. This employed FM and replaced the No. 19 in this role from 1954. As a result, the No. 19’s VHF ‘B’ section was abandoned and removed when sets were overhauled. The Royal Armoured Corps No. 19 sets were mostly replaced in the mid-1950s with a militarized version of the PYE PTC-202 known as the C12 as an interim measure, which were subsequently replaced with the C13 from 1960.[5] An additional RF amplifier for the No. 19 (Amplifier, RF No. 2) increased the daylight operational range up to about 45 miles (72 km). The experimental Wireless Set No. 19 TH (built for the Dutch Army) featured increased frequency coverage up to 12 MHz.

Post-war, the Canadian No. 19 MK II and III was used in the Swedish and Italian Army.”

Q&A regarding different micromhos scores

Hey Tubesound,

Hoping you can answer a question for me. I have an Amplitrex and a TV-7D/U tube tester.  The Amplitrex tests a 12ax7 as new at 1600GM.  According to your TV7 GM calculator, I believe that should translate to 64 on the TV meter.  However, when I test the same 12ax7 on my TV-7 the meter only hits 42.  Does it sound like my TV7 needs some calibrating or am I missing something? Hope you can help and thanks for the great calculator.

Read the rest of this entry »

Q&A regarding HP Officejet R-series repair

Q&A regarding HP Officejet R-series repair:

Hi,

I have your article on “Repairing HP Officejet R-series”.  I used it several years ago; cleaning  the mirror fixed the problem.

I’ve lost flexible use of my hands so I wanted to get someone to do the service (suspect it needs cleaning and new bulb).  Local repair services refuse to work on ink jets.

Do you have a recommendation for help in the south NJ area?

Thanks, Jim

Read the rest of this entry »

CBS Hytron 12BH7 letter about Hickok test

Here is a letter from the Technical Service department of CBS Hytron tube company, dated June 1954, that discusses a common problem with tube testers.

In this letter [ PDF ], which I scanned and restored via Photoshop for better readability, a person from the Max Fischman Co of Pittsburgh wrote to CBS Hytron Co. asking them why so many CBS Hytron 12BH7 tubes were testing weak on their Hickok 533A tube tester.

CBS Hytron investigated the matter by testing 50 CBS Hytron 12BH7 that were known to be top quality and passed factory testing.  They also tested 12BH7 from other manufacturers.  Their analysis revealed that the test configuration — the operating point — for 12BH7 as provided by Hickok was incorrect to target the listed micromhos value of 2380 µmhos.

Learning points from this letter:

  1. Again, as I have tried to instruct in previous articles, there is no such thing as a “correct” (or single) mutual conductance score.  Mutual conductance is a result of the operating point of the tube (plate voltage, signal voltage, grid bias, etc.).
  2. Factory setup data OFTEN provides a substandard operating point for the tube in question.  This is sometimes because of mistake or carelessness in creating the setup data, and sometimes due to design limitations of the test circuit (one fixed signal voltage that is substandard for a particular tube, or a fixed plate/screen voltage that is substandard for that tube).
  3. Learning to KNOW YOUR TUBE TESTER is of utmost importance, not blindly relying on the results that you see on the meter.  A seasoned tech who worked with 12BH7 tubes on a regular basis would have discovered this issue and learned to work around this problem — either by creating a new Bias setting that more appropriately would target 2380 for a typical new 12BH7, or he would have noted what Gm score was more accurate at the bias point given in the setup chart.

 

NOTES: (1) the letter refers to mutual conductance readings as “Sm”, which I am not aware of that abbreviation.  I believe that “Gm” is the standard abbreviation.  (2) the secretary who typed the letter misspelled Hickok as “Hickock”.

 

TV-7 micromhos conversion calculator

TV-7 tube tester micromhos calculator
Meter: µmhos

DIRECTIONS:

  1. Enter your meter reading (0 – 120) into the “Meter” box.
  2. Choose your Range Switch position in the drop-down box.
  3. Press the “Calculate Gm” button and read your micromhos score.
  4. Press “Reset” button to clear your entries or to start another calculation.
  5. Invalid entry ( meter > 120 ) will automatically reset the calculator.

NOTES:

  • calculator works for all TV-7 models: TV-7/U, TV-7A/U, TV-7B/U, and TV-7D/U
  • calculator requires javascript
  • Range A on TV-7 is only used for emission testing of diodes and rectifiers — no mutual conductance reading exists. Therefore, I have omitted Range A from the calculator. The Range A meter reading is an arbitrary emission score that is evaluated in relation to the “Minimum Value” notation in the setup book.
  • Range B signal voltage is 5.0v ac with bias 0 to -40 vdc
  • Range C signal voltage is 5.0v ac with bias 0 to -40 vdc
  • Range D signal voltage is 1.0v ac with bias 0 to -40 vdc
  • Range E signal voltage is 0.5v ac (500 mV) with bias 0 to -40 vdc
  • Range F signal voltage is 0.5v ac (500 mV) with bias 0 to -4 vdc.  Range F is 0 to 30,000 micromhos, not 60,000 as reported elsewhere.  Click to “Read the rest of this entry” below for details.
  • ©2014 TubeSound

Read the rest of this entry »


Valid XHTML Valid CSS