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> hp 410C vtvm, solid state vacuum tube voltmeter
hp 410C vtvm, solid state vacuum tube voltmeter
Extensive repairs to these units include; Original vacuum tube/transistor amplifier board ( A3) replaced with a 100% Solid State New Amplifier board. Test leads replaced or repaired as necessary....cleaned, missing and corroded hardware replaced, pc board connections cleaned, Q1 (+6vdc regulator) checked and replaced as needed.. Meter face replaced if necessary. A7 ( power supply/interface) board and A6 board (calibration board) are brand new PC boards..
A7 (power supply interface board) is Brand New (new design). ( NOTE: The new design A7 power supply/ interface board is now a solder-in as opposed to the original "slip-on-connector" style) The original "slip-on connector" design was prone to a never ending set of interconnection problems. **** This is a solid state version of the HP-410C. Case repainted HP Olive . AC Probe repaired or replaced; this unit is equipped with a Genuine HP AC ( Active RF) Probe with new TRIAX cable. DC Probe may be the stock HP, or the HP 412A Style , depending on what we have in inventory. DC Zero control added to units that did not have that rear panel adjustment built in from the factory ( very small number).
This unit has a brand new A6 (calibration) board installed. The new A6 board uses 15 turn Bourns trimpots. Calibration is smooth and with much higher resolution available as compared to the stock single turn HP potentiometers. External panels and meter "brow" re-painted. Panels repainted Olive, meter "brow" painted Light Grey. Computer style AC cord connector installed (some units used a HP oval connector), AC cord set furnished as part of sale. Unit is NOT checked for 220VAC operation.
No photo-chopper to cause shakey needle, sluggish readings and heat related drift. No vacuum tube to cause drift and heat, No high voltage components to burn up. Warm up time basically the time it takes to warm up the AC Probe (about 25 minutes to thermal stability) Very low drift over time, low power consumption, no heat buildup, leave the unit powered up 24/7. All this and more with the solid state 410C.
Serial Number of the unit you will receive is: [ 344-01780 ] Photo: [ UNIT YOU WILL RECEIVE ]
These instruments are lab-grade, easy to use and repair. They are rugged, accurate, have a design 100megohm input impedance, which makes them teriffic for low level signals and measurements that are not accurate unless very lightly loaded, (receiver AGC/AVC lines come to mind). They are just as useful in the ham shack ( helping to repair those great old boat anchor era electronics) as the lab or the classroom . The RF (AC) Probe (useful to 700mhz) is perfect for low level signal tracing in oscillators, mixers, and transmitter and receiver RF circuitry of all kinds.
Someone pointed out that , technically speaking, this instrument is not a "vacuum tube" unit . True. However these units are referred to as "VTVM"'s or Vacuum tube voltmeters" because, at the begining of their lives, they did contain a vacuum tube. We decided to stick with the original description.
****** NEVER EVER ATTEMPT TO MEASURE AC LINE VOLTAGE WITH THIS INSTRUMENT, THE CASE IS AT AC GROUND AND DOING SO WILL DESTROY THE INSTRUMENT *****
The bulk of the cost of this instrument is the active RF probe,whether the HP or Militarized versions. The cousin of this instrument, the HP 410B, while not nearly as modern looking, has a design input impedance of 122megohms, ( and an active RF Probe as well) , making it a great lower cost alternative to the 410C.
We custom fabricate the little "spring gizmo" inside the RF Probe, that is used to connect the tube top pin with the nose of the probe housing.( Occasionally these go missing.) We can supply replacement triax-cable when the HP triax on your instrument fails. See our web page "PRODUCTS PAGE" for details.
We can supply BRAND NEW replacement **A6 , A7 and A3 board sets,** . as well as replacement meter face (scales) . Email for details and see our website: "Products" page.
We provide after sale technical and parts support ,via email, for all of the units that we sell and for all that are listed on our web page. Technical questions about vacuum tube test equipment, parts, repairs and usage ? Email us.
We also service all of the types of electronics that we sell. Write for price quotes.
We repair/refurbish : URM 25/26, HP 410B,410C, HP 608 family ,HP200CD, Simpson 303,TS510 (608D military version), HP204C, HP 204D, HP 209A.
http:// / <~~~~~~~~ Our Web Page
