AN/PDR-27(*) RADIAC Meters

AN/PDR-27G

The AN/PDR-27G is a member of the first generation of AN/PDR-27(*) RADIAC meters that is comprised of the AN/PDR-27 through AN/PDR-27H and AN/PDR-27K. Originally it was powered by special military batteries; BA-416/U, BA-413/U and two BA-401/U.  As these batteries were no longer available, I converted it to run on commercial batteries consisting of two 1½ volt "D" cells, one NEDA 215 22½ volt battery, and two NEDA 217 67½ volt batteries.  However, the prices on the NEDA 215 and NEDA 217 batteries have become prohibitive over the years.

AN/PDR-27J through AN/PDR-27Q

The AN/PDR-27J through AN/PDR-27Q (excluding AN/PDR-27K) are from the second generation of the AN/PDR-27(*) RADIAC meter series. They run on six standard "D" cells (military type BA-30/U) and utilize circuitry consisting of a mix of tubes and transistors.  Transistors are used in the power supply circuits and tubes are used in the detector circuits.

I do not currently own a meter from this series.

AN/PDR-27R

The AN/PDR-27R is the third generation of the AN/PDR-27(*) RADIAC meter series. It runs on six standard "D" cells (military type BA-30/U) and was the first fully transistorized unit in the AN/PDR-27(*) RADIAC meter series.

AN/PDR-27S and AN/PDR-27T

The AN/PDR-27S and AN/PDR-27T are from the fourth and last generation of the AN/PDR-27(*) RADIAC meter series before the series was replaced by the AN/VDR-2. They run on two standard "D" cells (military type BA-30/U) and are fully transistorized.  The AN/PDR-27S was repurposed as the HDER-G01 under the Homeland Defense Equipment Reuse program.  The AN/PDR-27T was used by the U.S. Air Force. It is colored blue and has a removable probe.  I acquired an AN/PDR-27T in September 2017 from eBay for USD$50 shipped that needed some minor electronics work in the probe to get it functioning again.

Headphones

The original H-43/U headphones are hard to come by and are very uncomfortable. The newer H-43B/U headset appears occasionally on eBay as surplus and they tend to run in the US$15-$25 range. This is a picture of a pair of H-43B/U headphones that were acquired on eBay for around $12 due to a damaged cable that I repaired:

If you have a pair of H-43B/U headphones that did not come with cushions, like those pictured above, a pair of military surplus MX-41/AR (NSN 5965-01-331-8708) cushions will fit and make the headphones much more comfortable to wear.  This is a picture of the H-43B/U headphones above fitted with MX-41/AR cushions:

Later versions of the H-43B/U headphones have a more durable cable and include cushions:

Since the audio output of the AN/PDR-27(*) series is high impedance, just about any high impedance headphones should work fine with an adapter. In the following pictures, I have a pair of 600 Ohm Telex model 610 headphones along with a 1/4" audio jack to BNC plug adapter that I made using a BNC plug, a short length of RG-58 coax cable and a RadioShack #274-0340 1/4" inline jack. The Telex 610 headphones are inexpensive, comfortable and work fine with the AN/PDR-27(*) series. For those who do not wish to build an adapter, the Pomona 4043 adapter should work though it is a bit pricey and will most likely cost more than a set of H-43B/U headphones.

PP-4814/PDR-27C Power Supply

In the 1960’s, the logistics of keeping so many different types of special batteries on hand for various versions of the AN/PDR-27 series was becoming difficult.  In order to eliminate the need for special batteries, a transistorized power supply, the PP-4814/PDR-27C, was developed that allows the AN/PDR-27CY through AN/PDR-27H to be operated from five standard "D" cells (military type BA-30/U) instead of special batteries.  This power supply is documented in NAVSHIPS 0967-283-6010.

Using this surplus power supply I was able convert the AN/PDR-27G at the top of this page to an AN/PDR-27GX that now runs on five "D" cells.  The most difficult part of the conversion was coming up with the procedure to do it.  The conversion procedure is documented in 2-AN/PDR-27G NAVSHIPS 0967-896-5030 but that document was impossible to find.  Luckily the supplier of the PP-4814/PRC-27C power supply also sent me a copy of 3-AN/PDR-27H NAVSHIPS 0967-896-7040 that documents the procedure for converting an AN/PDR-27H.  While these two models are different, using schematics from both the AN/PDR-27G and AN/PDR-27H, I was able to develop a document outlining the conversion of an AN/PDR-27G to AN/PDR-27GX.  The only issue I still need to deal with is replacement of the display meter M101.  The AN/PDR-27G had not been used by me in about 15 years, due to the expensive batteries, and I neglected to test the meter before doing the conversion.  I still hear clicks in the headphones and the range scale works but there is no visual indication on the meter and tests show no impedance across the meter contacts.

Manuals

Last modified June 3, 2024