RETRO RECEIVER REVIEW #1 - DANSK RX 4000

RETRO RECEIVER REVIEW #1

A Chance to Walk Down Memory Lane!

I'm delighted to welcome friend and DXing colleague, Craig Seager, to the Mount Evelyn DX Report. For many years now, Craig has been the editor of the Shortwave Trail (the loggings section) and the Station News section of the Australian DX News (ADXN). Craig is one of Australia's finest DXers, a longtime listener with great experience in shortwave, mediumwave and other modes. His amateur radio callsign is VK2HBT.

Craig also has another special interest - old radio receivers. Last October I was delighted to visit him and see his very fine collection. He has personally restored most of these fabulous radios to full working order. His knowledge of communications receivers is extensive.
 
I am so pleased that Craig has accepted my offer of sharing his knowledge with myself and our MEDXR readers. All of these Retro Receiver Reviews were published in the ADXN, the monthly bulletin of the Australian Radio DX Club. So, sit back and enjoy Craig's first review. AND....if you do appreciate this and future reviews, PLEASE leave a short comment below. Craig and I would love to hear from you!

Click on each photo for a larger view.

DANSK RX 4000

by Craig Seager VK2HBT

Let's take a look at a professional quality receiver, this one is from the stable of Dansk Radio AS, a Danish company that was swallowed up during the mid 1990s and as a consequence no longer produces general coverage receivers.

 Often used in maritime applications, the Dansk RX 4000 was almost the last in its line and reigned from 1985 to 1991 – the RX 4010 followed, which was similar in appearance and, presumably, performance. Earlier, the Dansk M3000 was another quality set, but with a preselector in lieu of sub-octave filters in the front end, and less programmable options. 

 The RX-4000 is a synthesised, dual conversion design, covering 100 kHz to 29.99999 MHz, tuneable in 10 Hz increments.  It is rack mounted, and comes as a stand-alone with control panel, or basic receiver only for manipulation via RS232 interface.   A separate control head unit (RC 4000) can control a number of RX 4000 receivers, via modem if desired, or the RC4000 front panel can be simply unclipped and mounted on the front of the receiver for local operation.  A very neat arrangement, indeed.

 The RX 4000 is microprocessor controlled, facilitating push-button tuning via man-sized raised buttons, and there is also variable speed tuning using a rotary optical encoder. Up to 75 frequencies are user-programmable, with reception modes also stored. There is a built-in clock, which provides the useful ability to set up to 24 alarms, with programmable scanning, frequency change or muting.  An external recording device may be switched in automatically by the AGC circuit.  

 30 user-defined scanning programs are available, each containing up to six intermixed scannings or frequency changes with selectable dwell time.  Programmable features are stored in CMOS, and hence are retained when power is removed.   AGC settings (Off, Slow, Fast), modes (SSB, AM, RTTY, CW – all with adjustable threshold) and bandwidths are also selected by push-buttons, with the active setting indicated by a red LED under the relevant button. 

 The bandwidths (4) are well chosen for serious applications, rather than listening to music and the like, and can each be selected in all modes, except SSB which (somewhat unhandily) adopts a default value.   Rotary pots control notch, volume and RF gain, whilst another switches the receiver on and varies the brightness of the (red) LCD display.       

 Make no mistake, the RX 4000 is a beefy receiver – full rack width and heavy (15 kg). Construction is modular: each stage is comprised in long, individual circuit boards, which slot into a common bus.  The front panel then connects to the latter via a ribbon cable. The whole assembly is encased in a metal chassis, with a large heat sink at the rear. The chassis becomes very warm during long periods of operation, which is a bit disconcerting at first. The set is obviously built for potentially harsh environments. A vibration specification is even quoted in the manual for 1G of acceleration: My friend and fellow enthusiast John Schache suggested that this might be the force at which an unsympathetic spouse would throw the receiver out the door!   

 There is no (obvious) easy way to test voltages and components in-circuit without extension boards, with all internal parts inaccessible during operation. Other than that, replacement of components would be relatively easy and a quick glance at the list indicates commonly available IC’s. I suspect that in professional implementations, however, whole modules are probably replaced in the event of a fault, and identification of problematic stages is made easier by a built in test (BITE) that is activated by pressing the “clear” and “tune” buttons in succession.
        
The RX 4000 is a very well-performed and sought after receiver, designed with an emphasis on preventing overloading of the input circuitry and resultant spurious responses.  In common with many other monitoring station receivers, only a small speaker is provided, though there is a standard ¼” headphone socket on the front panel, and speaker + line out (adjustable level) connectors available from the rear. The antenna socket is 50 ohm, BNC.

 Some Specifications:
Sensitivity: 2 uV fpr 20 dB SINAD SSB, 8 uV for 20 dB AM
Selectivity: -6dB at ±2.7, ±1.2, ±0.5, ±0.1
Image and IF rejection: Both >90 dB
RF attenuator: 0 or 20 dB
BFO Range: ± 7 kHz synthesised in 10 Hz steps
Monitor Output: 4W into 4 ohms
Stability:  0.1 ppm -15 to +45º C,  0.3ppm -25 to +55º C

(This article first appeared in the March 2003 issue of the Australian DX News)

Thanks again, Craig. 
Missed the other Retro Reviews? Check them all out by clicking below:

Retro Receiver Review # 1 - The DANSK RX4000

 Retro Receiver Review # 2 - The HITACHI KH-3800W
  
Retro Receiver Review # 3 - The SCHAUB LORENZ ITT TOURING T104A RECEIVER

Retro Receiver Review # 4 - The RACAL RA6790/GM

Retro Receiver Review # 5 - The REALISTIC (RADIO SHACK) DX160

Retro Receiver Review # 6 - The KENWOOD QR 666

 Retro Receiver Review # 7 - The RODHE & SCHWARZ EK890

 Retro Receiver Review # 8 - The YAESU FR101S

 Retro Receiver Review # 9 - The SELENA VEGA B206

Retro Receiver Review # 10 - The DRAKE SPR-4

 Retro Receiver Review # 11 - The NATIONAL RF-5000

Retro Receiver Review # 12 - The YAESU FRG-100

Retro Receiver Review # 13 - The MARC NR-82 F1

Retro Receiver Review # 14 - The MURPHY B40

Retro Receiver Review # 15 - The STROMBERG CARLSON AWP-8










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© Rob Wagner, Mount Evelyn DX Report, and contributors 2012-2024

Comments

  1. peppermint loungerOctober 1, 2015 at 11:25 PM

    Great to see Craig's reviews being published here Rob. Keep them coming. Phil in Darwin

    ReplyDelete
    Replies
    1. Rob WagnerOctober 2, 2015 at 10:40 AM

      Good on you, Phil. Thanks for the feedback! We'll have another one up soon. Rob.

      Delete
  2. Old Film GuyOctober 2, 2015 at 12:06 PM

    Very enjoyable, and looking forward to further reviews. Got to love those old classic radios! Found you via SWLing Blog by Thomas Witherspoon.
    Cheers!
    Robert AK3Q
    All Things Radio Blog at ak3q.com

    ReplyDelete
    Replies
    1. Rob WagnerOctober 6, 2015 at 7:59 AM

      Hi Robert. Thanks for the feedback, much appreciated. I'll pass your appreciation onto Craig. Yes, Thomas is a good man, doing great things for the radio hobby. I have also seen your "All things Radio" blog since it began a few months ago, keep up the good work! Best wishes, Rob VK3BVW

      Delete
    2. Old Film GuyOctober 8, 2015 at 1:06 PM

      Thanks for the kind words about the blog - it's a great hobby and a lot of fun to share it with others. Cheers! Robert AK3Q

      Delete
  3. AnonymousNovember 6, 2015 at 9:14 AM

    Could not agree more. Both the M3000 & M4000 are great & very useable receivers.
    I have restored one of each with the same to go.
    Bill Tweedie
    Batemans Bay NSW

    ReplyDelete
  4. UnknownNovember 12, 2015 at 9:34 AM

    I have a dean M3000 to repair for as local museum. It was working for the previous owner, but suffered a power supply failure on the 5V line. He obviously repaired the PSU fault adn replaced some ICs on the processor board, but it never worked again and he sold it to the museum! I've replaced the processor and the address and data lines are active, but nothng appears to be coming off the processor board to the main reveiver. There is noise in the headphones indicating that the audio stages are working, but there are no lights on the front panel and none of the controls other than volume respond. I suspect that when the PSU failed the 5 V line went high and took an ubnknown number of the 7400 series logic chips with it. Does anybody have any suggestions?
    Many Thankd - Michael

    ReplyDelete
  5. UnknownNovember 13, 2015 at 6:59 AM

    Sorry, should be "dead" M3000, not "dean" - Michael

    ReplyDelete
    Replies
    1. UnknownDecember 1, 2015 at 10:56 PM

      Michael, I have found several unexplained issues with the M3000 in the past to be traceable to the front panel assembly. These have manifested themselves in various ways, including audio amplifier hum present (but no RF). Typically, the fault finding has taken me in other directions initially, based on the symptoms, but swapping out the front panel (or addressing dry joints) has done the trick. Worth considering.

      Craig.

      Delete
  6. UnknownAugust 29, 2021 at 1:33 PM

    I had the opportunity to work on these radios from 1994 to 2007. We had 6 of these radios. All worked on a 24*7 basis. Now all are none functional. It was a great radio with the finest keyboard. I wish to repair it. So far not been able to diagnose the problem.

    ReplyDelete

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