1307 Transistor Oscillator &
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1307 Transistor Oscillator![]() |
1307 Transistor Oscillator
Battery![]() The battery is held by a matal strap clamp that's difficult to access. Why would they solder in a battery and make it so difficult to change. Ans. It's a Mercuty battery and was expected to be replaced by the factory. The corrosion from the battery locked the Level pot and the two set screws holding the Level knob on the pot shaft. Kroil freed up the pot shaft and one of the pot set secrews. Will need to wait till tomorrow to see of the other set secrw gets free. There are patent numbers on the bottom of the battery: ETAL 2542575 Alkaline Dry Cell, 2712586 ? 2636062 Electrochemical Cell and Self-Venting Enclosure, Mallory 2462998 Primary Cell with Permanganate Depolarizer RE23427 Primary Cell with Permanganate Depolarizer, |
Battery Removed![]() |
To remove the battery: Remove the two knobs (requires being able to turn them to access the two set screws on each shaft). Remove the screw that between the two knobs. Remove the two nuts on the back of the meter movement. Fold the board out and remove the hex spacer that holds the battery clamp. In the photo at left the top electrical contact is (+), you can see "+" scratched on the back of the front panel. Notice the battery is like a bar bell with ends that are larger in diameter than the center so it can NOT be slipped out. |
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With
the Level pot at max it takes at least 3.4 V (6 ma) of
battery to get the meter to read 2V (the calibration value
for the 1552-B. With the battery voltage at 9.0 (5 ma) the level pot has plenty of room on both sides of a meter reading of 2V. A 9 Volt battery is a little too big to fit where the old mercury battery was. An A23 battery (12 Volts) is very small. I soldered a red and black wires and confirmed that the polarity was correct. Then folded the wires so the point to the opposite end and applied heat shrink tubing. Soldered into the 1307 without using the bracket since it's way too big and the battery is so light the leads hold it. All's well. First application is to see what's going on with the mike on the Harris RF3200ET. |
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1552 Sound Level Calibrator![]() |
1552 Sound Level Calibrator
Cavity![]() |
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Control End Shown in 125 Hz position (red background). Circle to the right is the battery test lamp. Start/Bat Test - OFF - 2000 - 1000 - 500 - 250 -125 Hz The frequencies are each twice the next lower one. Probably not designed for communications, but lab mike calibration. ![]() |
Source End Open end I.D. = 1.053" Adapter I.D. = 0.939" knurled screw on side allows opening case & acts as the ground side of a 1/4" phone jack. ![]() |
Battery Compartment Takes 9 V battery with terminal on each end. NEDA 1600 Eveready 226 UK PP4 CM345 Battery test lamp (6 V @ 60 ma) at lower right. Voltage at lamp base vs. lamp current:
With 9 V at battery terminals, switch in START, lamp voltage is 6.3V caused by R110 (62 Ohm) and Q105 Vces (0.3V). ![]() |
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4 each AAA batteries can be
used for the battery. It's only 6 V instead of 9 V and so takes longer for the thermistor to come up to temperature, but then works fine. A problem when testing the Harris RF23200ET mike is that the lowest two frequencies (125 & 250 Hz) are below the 300 to 3000 Hz voice band. |
Using button cells is not a
good idea since the current this unit draws (a few ma) is way in excess of the max design current for the button cells so they would have a very short life. |
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This gives an advantage to
the 1552 in that it can be driven from an external oscillator, like the HP 33120 Function Gen. |
GR 1565-A Sound-Level Meter![]() |
GR 1565-A Sound-Level Meter![]() |
GR 1565-A Sound-Level Meter
Opened. Battery clips for a common "C" cell. The mike can be removed and the -P40 Amplifier installed. ![]() |
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GR 1565-B Sound Level MeterCalibrate with 1562. GR 1560-P96 Type 1971-9605 MicrophoneMicrophone 1560-P96 adapter to 3-pin male A3 |
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Accessories mentioned in manual:
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GR 1560-P40 X1 or X10 AmplifierHi input Z, low noise for 1" Ceramic mikes.Fig 6-16b pg 101 Noise Meas Handbook 2 Socket End ![]() |
GR 1560-P40 X1 or X10
Amplifier XLR 3-Pin end ![]() |
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GR 1560-P52 Vibration PickupHas 1/4-20 tapped hole in the center of the back.Two clearance holes for mounting. Missing the short cable with XLR connector that would mate with the 1560-P96 adapter. ![]() |
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GR 1560-4100 Phantom Battery Power SupplyThis box was covered with tape residue and was missing a number of screws.![]() The Battery test lamp is a GE 344 and it measures 100 Ohms, seems too high. 10 V 14 ma equates to 714 Ohms hot resistance, the cold resistance will be lower. |
GR 1560-4100 Phantom Power
Supply w/ Ni-Cad batteries![]() |
GR 1560-4100 Phantom Power
Supply w/ Ni-Cad batteries![]() |
Using a bench power supply
set to 65 Volts and current limited to 18 ma, each battery has been soaked for about a day. They each show a charge of slightly more than 12 Volts. When the Battery/Charge switch is on Battery There is 20+ volts on the XLR socket contacts 1 (ground) & 2 (+20.87 V). |
CordsAC Stacking Line Cord for GR 1560-4100 Phantom Power Supply![]() |
1560-P95 1/4" Phone Plug to
Dual Banana Plug Cable for GR 1560-4100 Phantom Power Supply Output ![]() |
Vibration Pickup to XLR
3-Pin Plug to feed signal to 1560-4100 and receive phantom power from 1560-4100 ![]() |
XLR Extension Cord![]() |
Adapters1560-P98 GR-874 to 2-Pin Audio Adapter![]() |
1560-P98 GR-874 to 2-Pin
Audio Adapter![]() |
1560-P82 Earphone Coupler, Audiometer
Calibration Set![]() |
GR-874 to Dual Banana Jack
adapter Patent No. 2548457 Coaxial Connector for High-Frequency Transmission Lines, GR, Apr 10, 1951, 439/583; 174/21.00R; 174/21.0CA; 174/88.00C ![]() |
1560-?
Stand![]() |
1560- Suitcase![]() |
This sound level meter comes in a carry case with a Type 457 calibrator and an instruction booklet.
The calibrator can be used stand alone to generate a -106 dB A-weighted 1 kHz tone when +9 volts is applied to the tip and ground to the ring terminal.Note: the CAL 1/8" mono jack is in parallel with the battery supply (after the ON switch) so can be used as an external (always on) DC power input jack.
The meter displays a range of 10 dB, hence there are two index marks for the range switch, one for the left side of the meter and the other for the right side.
This particular meter is not working. Maybe there are some bad electrolytic caps? No. The problem was corrosion on the 9V battery connector, it's now working and calibrated.
(only off less than 1 dB).
Also see References for more on Edgerton and GR strobe lights.
page created 11 Jan 2012.