The R-390A Owners Manual
by
Chuck Rippel, WA4HHG
Congratulations!
You are the proud owner of a Collins designed R390A/URRgeneral coverage, HF radio receiver. In many circles, the R390A is consideredto be the finest HF radio receiver ever built. Weighing in at 85 lbs, thiselectro-mechanical wonder was designed in the early 50's and released February24, 1954 which also happens to be my birthday. Thanks to features such asa 6DC6 first RF amplifier, a suite of Military Grade Collins mechanicalfilters and full tracking RF and IF sections, the R390A is capable of copyingsignals down to its -143db noise floor, close to the galactic limit. Allthis while operating in high over load/strong signal environments.
Originally built by Collins Radio Company in CedarRapids, IA, the R390A was designed by 2 teams. The mechanical team beinglead by Fred Johnson while the electronics team was overseen by Ernie Pappenfus,K6EZ. Besides Collins Radio, there were 13 other sub-contractors which builtR390A's until the last one rolled off the assembly line in 1984. Banks ofthese fine radios served the country in all branches of the military andalso the CIA and NSA for monitoring communications from behind the IronCurtain during the Cold War years where the R390A was classified TOP SECRETuntil the mid-1960's. Stories are told that R390A's are still in use bythe NSA where senior operators far prefer their quiet, yet stellar performanceover modern, mega-dollar receivers from Harris, Racal and Watkins-Johnson.
I hope you enjoy this wonderful radio, unduplicatedin performance and rich in history over the many years of service it stillhas to offer.
-73-
Chuck Rippel, WA4HHG
Collins Collectors Association
- Care And Feeding
- Resources
- Hamfest Shopping List
- Restoration Summary
- Sensitivity Performance Summary
- Some Targets to Hear on the R390A
- Operating Notes
Before powering up the receiver: There is nothingreally very different about owning and operating an R390A but there area few issues to be aware of. By now, you know that this radio is quite heavy!Weighing in at 85 pounds without the accessory cabinet, your R390A is a"boatanchor" in the truest sense. Keep this in mind when consideringa location and operating position; placing it on a light desk or TV tablemight result in this 85 pound radio ending up in your lap! Another considerationis the amount of heat given off by the R390A's 26 vacuum tubes using both6.3 and 12.6 volt filaments. Make sure the radio has adequate ventilation.Finally, and perhaps most important, before plugging in or powering up theradio, be safe! Make sure your R390A has a good electrical and RF ground.
The audio output of this receiver is much like mostother military receivers having a 600 ohm impedance. This means, if connectedto a regular 8 ohm loudspeaker, it will sound weak and distorted. The "localaudio," that is, the audio controlled by the "local gain"control on the front panel appears on pins 6 & 7 on the left hand terminalblock as viewed from the rear of the receiver. The impedance mismatch whenusing a 4 or 8 ohm loudspeaker can be overcome easily. The first solutionis to purchase a 600 to 8 ohm AUDIO transformer. These can be found (attimes) at Fair Radio for about $8. An easier solution is found right atthe local Radio Shack. Purchase a 70.7 volt line transformer (cat. Number32-1031) and connect the primary terminals marked "C" and "10"to terminals 6 and 7 on the left hand terminal block located on rear ofthe R390A. Then, connect the secondary side of the transformer, terminals"8" and "C" to your 8 or 4 ohm speaker. This will resultin an 500 to 8 ohm match which will give good performance. A closer matchmay be realized by using a 25 volt line transformer and using the same configurationas above save for choosing the "1" and "C" taps on theprimary side of the transformer. The secondary wires as above in the 70.7volt line transformer.
The antenna connection is even more simple. The radiohas been aligned using the "Balanced" antenna input located onthe rear of the receiver. Turn the receiver around and face it. TB-102 willbe on your left and TB-103 on the right. The "Balanced" antennainput is located in the upper middle. Examine the connector and notice ithas two holes for pins located within the connector. Simply tin your antennawire and insert it into the right hand pin hole. Insert a wire in the lefthand hole and ground it using one of the screws which hold the antenna relayunit to the rear panel. The "Unbalanced" antenna input can alsobe used but with a decrease of performance unless it was aligned to thatinput.
If you wish to use the proper connector, there areseveral approaches from which to choose. A combination of a UG-971/U anda UG-636A will adapt a BNC connector to the "balanced" antennainput. A UG-970/U will adapt a PL-259 to the "balanced" antennainput. A UG-636A/U will also adapt a BNC directly to the "unbalanced"antenna input.
The vacuum tubes originally had black, heat dissipatingIERC tube shields installed on them. According to a study done by CollinsRadio, this increases tube life by up to 53%. If your radio does not havethem or simply has shiny heat shields which have been painted black, itmight be a good idea to pick up IERC shields at a hamfest. The R390A usesthree sizes, short 7 pins, regular 7 pins and regular 9 pins. These havegotten expensive of late as more and more tube enthusiasts realize theirworth.
A couple of other "don'ts" come to mind.To keep the receiver stable, DON'T, turn on the "ovens" switchlocated on the back panel of the receiver. It causes the receiver to steadilydrift in normal temperatures and can also cause the PTO to be irreparablydamaged should the thermostat fail causing the oven to lock "on."Another tip: if the receiver is going to be left on but not in use, DO NOTuse the "STANDBY" position on the FUNCTION switch. The now unloadedstages will cause the various voltages in the receiver to rise upwards perhapsbeyond the tolerances of some critical components. This is caused by themultiplicity error in our sometimes 120v+ line voltage v/s the 115v in usewhen the 390A was designed and built. Since it is normal for the "LOCALGAIN" control to not completely mute the audio when turned down fully,it is natural to consider putting the receiver in "STANDBY." Remember,DON'T. Instead, turn the audio down and also back off the RF GAIN controlto about 11 o'clock and the residual audio will disappear and no damagewill be done to the receiver.
One of the mods I install is a precision replacementpot used to zero the "CARRIER LEVEL" meter. It is located on thetop of the IF chassis (chassis module behind the "LINE LEVEL"meter). To adjust it, let the receiver warm up for about and hour then unplugthe antenna and tune the R390A to a dead spot on any band. Remember, theR390A is VERY sensitive and simply unplugging the antenna is not 100% insuranceof completely removing a signal. Once a dead spot has been located, zerothe "CARRIER LEVEL" meter with the presicion control.
The "IF OUT" connector on the rear of thereceiver can provide an IF signal to the VERY EFFECTIVE, highly recommended,Sherwood SE-3 synchronous detector. An SE-3 and R390A combination are a"deadly" combination of classic tube engineering and modern technology.I have found that using the SE-3 MK3D, the operator is able to recover about30% more useable audio from a given AM signal with more fidelity and farless distortion than the R390A alone. All of this, without the shortcomingsof todays receivers using "modern," (cheap) engineering approaches.
Speaking of audio, supurb results can be realizedby coupling the "DIODE LOAD" point on TB-103 located on the rearof the receiver to a Hi-FI amplifier. Simply obtain an audio extension cablewith an RCA plug on one end from Radio Shack. Place a 470K resistor in serieswith a 10uf, non-polarized (also available at Radio Shack) capacitor andconnect it to one of the screws holding the jumper across the "DIODELOAD" screws on TB-103. Do not remove the jumper. Connect the otherend of the capacitor/resistor network to the center conductor of the RCAcable then ground its shield to the "GND" screw located on TB-103immediately to the right of the "DIODE LOAD" screws. Plug yourcable into the TAPE or AUX jack on your stereo receiver, adjust the tonecontrols as appropiate and enjoy.
For EXCELLENT AUDIO, try tuning into the VenezualeanEcos del Torbes after local sunset on 4980. Open the "BANDWIDTH"to the 8kc position and enjoy some of the best hollow state audio you willever hear!!!
Index
Builders of the SE-3 MK3D and other useful items.I have personally had very satisfactory dealings with Bob Sherwood beginningin 1975 when I bought a modification package for my Drake R4-C. While theSE-3 MK3D is not effective in receiving SSB, I cannot recommend it highlyenough for achieving top AM performance with the R390A.
Sherwood Engineering
1268 Ogden Street
Denver, CO 80210
(303) 722-2257
P.O.C.: Bob Sherwood
The Hollow State News focuses on service and useabilityissues on receivers such as the R390A, Hammarlund SP-600 and HQ-180(A).Recently, Charles Talbot, K3ICH has offered a bound reprint compendium ofall issues of the HSN. Contact him directly for information and pricing.
Charles Talbot - K3ICH
13192 Pinnacle Lane
Leesburg, VA 22075-6146
HSN $5 for a 4 issue sub. Back issues $1 each andas if 1/1/97, we are at issue #39. Make checks payable to: Ralph Sanserino.
Ralph Sanserino
PO Box 1831
Perris CA 92572-1831
Original manuals can be purchased from: National Technical Information Service
Technology Administration
U.S. Department of Commerce
Springfield, VA 22161
The NTIS Sales Desk is available between 8:30 a.m. and5:00 p.m., Eastern time, Monday through Friday.
Sales Desk: (703) 487-4650
Subscriptions: (703) 487-4630
TDD (hearing impaired only): (703) 487-4639
Mail Orders Send orders to:
NTIS
5285 Port Royal Road
Springfield, VA 22161
Fax Orders (703) 321-8547
Fax service is available 24 hours a day, 7 days aweek. To verify receipt of your fax, call (703) 487-4679, 7:00 a.m. to 5:00p.m., Eastern time, Monday through Friday.
Noted Electric Radio Author Bill Kleronomous, KD0HGwill modify an existing R390A audio chassis to provide "hi-fi"sound backed with about 5 watts of push-pull power. As an added bonus, the600/8 ohm audio matching transformer is no longer required. So, if you wantto hear excellent audio from your R390A, consider obtaining a spare audiochassis and send it to Bill to modify. While not especially attractive forDX'ing, I can personally attest to the improved audio for the program listener.Contact Bill for current availability and pricing at:
Longmont Audio Labs
224 Main Street
Lyons, CO 80540
(303) 823-6438
Yes, thats right. Cabinets! You can purchase topquality vintage-type metal cabinets which fit the R390A. These are evencomplete with piano hinge top covers! The best part is the price, about$125 for the "DCR" series cabinet as of 1997.
Premier Metal Products Company
381 Canal Place
Bronx, NY 10451
(718) 993-9200 (East Coast)
(909) 829-3089 (West Coast)
While the CCA focuses largely on Collins' contributionto amateur radio products, membership can be helpful to R390A owners. Irecommend membership in the CCA. Any person who has an interest in CollinsRadio is welcome to join. Annual dues are $15 per year for those livingin the US and $18 for Canada. This includes a membership certificate andthe quarterly newsletter, The Signal.
Mail your remittence in US funds to:
The Collins Collectors Association
PO Box 840924
Pembroke Pines, FL
33084-0924
ER publishes a monthly magazine about the size andformat of the current NASWA Journal. It is a very worthwhile publicationand focuses entirely on tube or "hollow state" receivers and transmitters.Electric Radio is $38 per year mailed first class and $28 for 2nd class.Canada is $39.
Electric Radio
P.O. Box 57
Hesperus, CO 81326
Fair Radio has been around since 1947 and sells,among other things, R390A parts and entire sub-chassis. Their prices are,in my opinion, a little on the high side of reasonable but Fair has alwaysgiven me excellent service.
Fair Radio
PO Box 1105
Lima, OH 45802
(419) 223-2196
Antique Radio supply caters to the hollow state enthusiast.They have a large selection of vacuum tubes and other goodies.
Antique Radio Supply
6221 South Maple Street
Tempe, AZ
(800) 706-6789
For those interested in listening to Shortwave Broadcastor Shortwave Broadcast DX'ing, NASWA fills the bill. They publish a monthly60+ page bulletin with program schedules, features, DX listings and otherS.L. material. NASWA is the oldest SWBC focused organization in North America.A sample bulletin can be obtained for $2 from:
NASWA
45 Wildflower Road
Levittown, PA 19057
Index
It is never a bad idea to have a few spare parts around for your R390A.Even though the receiver was designed and built to the highest quality mil-specstandards using silver plated contacts, all stainless steel hardware, modularconstruction and industrial grade tubes, it can still break. The spare receiverI bought for $50 a few years ago as well as this stock of replacement tubeshas proven invaluable the few times mine has actually needed repair.
This is the suite of vacuum tubes used in the '390A.It is a good idea to pick up at least 2 complete suites of tubes while theyare still reasonably priced and even better to have 4. Make a few copiesof this page and take it with you to the next hamfest. Always try and purchasethe industrial tubes. These are the underlined numbers.
Tube Type | Quantity | Price Each (1996) |
6AK6 | 3 | $2 5 |
5654 | 2 | $2 5 |
12AU6/5814A | 2 | $2 8 |
26Z5W | 2 | $10 20 |
3TF7 | 1 | $20+ |
6BA6/5749W | 6 | $2 5 |
6C4/6100 | 3 | $2 5 |
6DC6 | 1 | $5 10 |
OA2 | 1 | $5 10 |
Total Tube Count: 26
As of this writing, tubes are not as difficult tofind as some of the handwringers might say. On the other hand, the numberof available tubes is finite so consider building a stock with the goalhaving at least 4 complete sets on hand. Also, always try and purchase JANtubes. These are found in plain, white boxes, are labeled JAN and also showthe date of mfg on the box. In the case of the 6BA6, 12AU7 and 6C4, tryand purchase the 5749, 5814A and 6100 respectively which are premium tubeswith JAN/Industrial specifications.
** NEVER, EVER INSTALL CHINESE OR RUSSIAN TUBES IN AN R390A!
(Unless there are no more US tubes left on the planet)
The R390A uses 5 different sizes of heat dissipating,black, IERC tube shields. Installing the correct type and part number shieldcan dramatically decrease the operating temperature and in turn, increasethe life of the vacuum tubes. Collins addressed this back in the early 50'sin service bulletin #303 which graphically compared the beneficial performanceof various types of tube shields with not using shields at all.
The proper tube shields can easily identified. Theyare anodized black (or deep purple), have an open top with a series of tabsfolded over a thin, octagonal metal tube inserted longways inside the shield.They are also plainly labeled "IERC." There is a unique modelnumber stamped on the outside of the shield denoting which size it is designedto fit. Refer to this number when obtaining the shields.
Below is an inventory with individual quantities of the5 different part number IERC tube shields used in the R390A:
Part Number | Quantity | Description |
6025-B | 1 | Tall 9 Pin, used for the ballast tube |
6020-B | 9 | Medium 9 pin, used on 5814A's and 26Z5W's |
5015-B | 2 | Short 7 pin, used on the 5654's |
5020-B | 13 | Medium 7 pin, used on 6BA6's, 6C4, 6AK5, etc. |
5025-B | 1 | Tall 7 pin, used on the OA2 |
Black tube shields labled "WPM" my alsobe found. While I personally don't feel these are quite as effective asthe IERC design, they are far and away better than the shiny types describedbelow.
Radios which still have shiny tube shields shouldhave them replaced with the above IERC shields as soon as possible. Evenif they have been painted black on the outside, these shields have no provisionto grip the tube bottle and sink the heat away from it. Also, the brightinside surfaces of the shield actually reflect the heat back into tube andon to the dark internal plate structure which could cause the tube to overdissipate and shorten its service life.
Index
For: Owner:
Order Number:FR-36-039-N-8-0189(E)
Each R390A/URR that I rework has many hours investedin the electronic, mechanical and cosmetic restoration process. Each receiveris given a thorough general operational check before the restoration processbegins and any problems or deficiencies corrected. Below is a brief, generalchecklist of what was done to this particular receiver. Other, specificitems are addressed on a unit by unit basis according to need and may notbe specifically noted here.
- General- Electronic & Mechanical
- Main Chassis Assy/General- Cosmetic
- RF Sub-Chassis Assy
- P.T.O. Sub-Chassis Assy
- IF Sub-Chassis Assy
- AF Sub-Chassis Assy
- Power Supply Sub-Chassis Assy
Prior to final Q.C., each radio is operated for afull 3 hours. This allows the unit to properly heat-saturate before a fullalignment of:
Notes:
Index
R390A Sensitivity Performance Summary
EAC Mfg R390A #905
Order #FR-36-039-N-8-00189(E)
After completion, each radio is checked for sensitivityand general performance on significant bands used by the SWBC DX'er andAmateur Radio Operator. Below is a final post-restoration performance summaryfor this receiver.
Band Frequency 10db S/N + N Sensitivity (uv) 4kHz filter,AM
120M 2.2 MHz
90M 3.3 MHz
60M 4.8 MHz
49M 6.0 MHz
41M 7.1 MHz
31M 9.6 MHz
25M 11.8 MHz
20M 14.2 MHz
19M 15.2 MHZ
PTO End Point Error:
This R390A/URR Restored and Tested For:
Index
Some Targets to Hear on theR390A
Evaluating the performance of this receiver by listeningto the amateur bands or the BBC is a little like looking across your yardwith a telescope. You don't really find out much more than you already knew.Here are a few Shortwave Broadcast DX targets to try for. All are just abit on the difficult side. The challenge just might surprise you and openup a whole new hobby segment, Short Wave Broadcast DX'ing.
All listings are by UTC time:
Index
Because your BFO makes a great AM tuning aid, ithas been carefully set up to help you perfectly tune a station. Ever wonderwhen a station is perfectly tuned and in the center of a filter passband?That is quite important for best audio recovery and lowest distortion.
Your R390A has 4 Military-grade Collins MechanicalFilters plus 2 crystal filters in the IF section whose center frequencyis 455KC. I have optimized their center frequency very carefully duringalignment. Additonally, the BFO has been precisely set to zero beat witha 455KC signal coming through the IF when it is set to "0" orcenter on the front panel scale. Here is how to use the BFO as a tuningaid:
A. Make sure that the white marking line on "BFO Pitch" knob lines up exactly with the "0" mark on its front panel scale.
B. Select the filter you wish to use.
C. Turn the BFO on then tune the main, "Kilocycle Change" control for an exact zero beat with the carrier of the desired station. Do not adjust the BFO control to attain zero beat!
D. Turn off the BFO and monitor the broadcast.
Using this technique, the desired signal is centeredexactly in the IF passband. You are assured of maximum audio recovery withthe lowest possible distortion.
Remember, this technique is for AM only. SSB, a klugeon the R390A at best, requires a different procedure. Index
Back to the General Technical Page
13 January 1998