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| Reviews Summary for Philips M.E.L. - PRC-2000 |
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Reviews: 5
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Average rating: 5.0/5
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MSRP: $Unknown
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Description: Military, compact man-pack radio HF SSB
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More info: http://
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write your own review of the Philips M.E.L. - PRC-2000.
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KA4KOE
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Rating: 5/5
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Aug 8, 2009 15:14
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Republished Older Technical Review
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Time owned: more than 12 months
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Lately many PRC-2000s have been sold through Ebay from a company based in the UK, in brand-new condition, and of late-manufacturing date (1992). I assume this company has acquired the last stock of these radios from Philips-MEL just before MEL was sold by Philips (read: ceased to exist). My PRC-2000 I indeed got through Ebay from this source, I must say I was not disappointed when I got it.
The PRC-2000 is a British made military radio, produced by Philips-MEL before that company was acquired by Thorn-EMI. Its frequency coverage is 1.6 MHz to 30 MHz in 100 Hz steps.
It was developed for military field and vehicle use. It apparently saw its first deployment in the Falkland war in the early eighties where it apparently performed well (Source: Janes Military Communications 1986).
The PRC-2000 is primarily a man-pack radio, (relatively) light-weight and has room for a NiCad battery in the bottom of the radio. In this configuration it can be worn in a back-pack configuration, using a whip antenna and a handset. There also is a vehicle configuration (called the GRC-2000), where a power-conditioner module having the same dimensions as the battery replaces this battery, and where the PRC-2000 radio is placed on a vehicle mount using a fast mount-&-remove mechanism. In this vehicular configuration, the radio can be operated anywhere from 10V DC to 32V DC, as the power conditioner regulates this back to 14V DC for internal radio operation.
In the vehicular configuration, there also exist a separate power amplifier-tuner to beef-up the 20 watts RF from the radio to about 100 watts. In this configuration, the transceiver digitally controls the amplifier/tuner through a serial control signal which is transferred through the same RF connection that connects the RF output from the radio to the amplifier. So no extra control cable is needed here.
The downside from this method is that under certain conditions some digital noise can he heard on the RF, also in the manpack mode without the amplifier. This is mostly the case in the band 1.6 MHz to 3 MHz, beyond that it is not significant.
The PRC-2000 has the same footprint as the Philips-MBLE RT-600 HF radio (Belgium) and the VHF radio Philips-HSA RT-3600 (Dutch). They all use the same vehicle mount and same battery.
The PRC-2000 radio is conceptually an excellent example of a ?thinking outside the box? design. The RF concept is basically that of a direct-conversion type, where the RF is directly mixed down (or up, during xmit) to (from) baseband using an image-reject mixer approach (also called an I-Q mixer concept).
This is done through two high-level ring mixers, each accepting the same LO signal but the Q chain has the LO signal 90 degrees shifted. Sideband reversal is done by (digitally) change the LO phase for the Q mixer from +90 degrees to -90 degrees.
Using this concept assures the opposite sideband is sufficiently rejected for both transmit and receive. And when I say sufficiently, I mean REALLY sufficiently, close to 60 dB. This approach also means the concept of an image frequency (due to a 1st IF) is unknown to this radio; the only image product is in fact the suppressed sideband. The manual triumphantly touts this; Receiver image rejection: Not applicable?
The direct-conversion concept also means the audio filter IS the IF filter. So no crystal filter is used here as the passband-determining filter; it is realized as a chain of hi-Q LC pot-core resonators having many poles. This results in an exceptionally good receiver passband curve, and an audio quality very pleasant to listen to without any ?SSB fatigue? so characteristic to some of the (earlier) Japanese radios.
One wonders why such an I-Q direct-conversion concept is not used in today?s DSP based radios; decoding and filtering in the audio passband should be a cinch for a DSP. The reason is probably because direct-conversion allows only for SSB radios, modes as FM (and AM) would be a problem here.
The radio has very good sounding modulation, partially due excellent speech processing. The speech processing is done by mixing the baseband AF to a 1.5 kHz IF (not a typo for ?MHz?!) and then back to baseband again in a concept I still do not fully understand. It results in the sideband being ?folded in half?. It doesn?t happen often that I do not follow the concepts of my radios, but this is such a case!
Another out-of-the box idea is the way the frequency synthesizer makes the 100 Hz steps (traditionally a challenge to accomplish this phase-noise free for ANY HF synthesizer before the DDS era). Adding some kind of modulation in the loop-filter does this, but again the exact mechanism behind this concept (still) escapes me. But the result contributes in giving this radio a very good receiver as a whole.
Another advantage over your everyday radio is the AGC attack and decay. This works so well in this radio you wonder why not all radios have AGC?s this smooth. Its AGC decay does not slowly ebb away, it stays flat for about half a second and then suddenly releases. An effective built-in noise-blanker makes sure the AGC does not attack on noise spikes which otherwise could be a problem for such an AGC concept.
The construction of the radio is done very well. The casing is diecast aluminum all around. Opening it up reminds of the older Philips oscilloscope construction in the days these instruments were still allowed to cost some bucks. All circuits are modular on glass-epoxy. In general, the Philips PCB boards always looked so much ?cleaner? and ?orderly? compared to the competition; this radio gives you the same impression.
All internal frequencies are derived from one high-stability master oscillator. The whole radio is under CPU control, including the volume control. All settings go through UP/DOWN buttons. Frequency step size for the UP/DOWN control is fully programmable from the keypad, any step size can be made.
The display is formed by a large backlit LCD showing frequency, mode and memory channel (10 can be programmed), as well as relative forward and reflective power.
RF power can be set for low (4 watt) and high (20 watt). There is a built-in automatic antenna tuner but this is designed to work only with the whip; the tuner can not tune random antennas. The tuner can also be bypassed for stationary operation, by removing a BNC-to-BNC link on the front-panel.
When using a special handset, the 10 memories can be selected directly from the handset without the need to reach to the control panel (as the latter would be somewhat difficult to accomplish by an operator in man-pack configuration). The radio does this by sensing a variable resistor from the hand-set; each value corresponds to a certain channel. Simple but effective?
Supported modes are LSB,USB, CW and FSKL/FSKU. The latter two are basically LSB and USB without the speech processor, and with fast AGC decay. Filter bandwidth for CW is unchanged from USB.
I have made many contacts on all bands with this radio, the 20 watts it offers is more than sufficient to reach out. Quality of the modulation always gets me very positive sound reports. And as said, the receiver is a pleasure to listen to. These radios go on Ebay for about $1500 US, in new condition. That really is a steal for the quality of radio one gets.!
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N8DNX
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Rating: 5/5
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Apr 24, 2009 19:32
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Stunning Radio!
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Time owned: 0 to 3 months
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I'm now on my second PRC-2000. The real question is why I sold my first one (twice). Fortunately I was just able to acquire another one that was NOS (New Old Stock) and had never been used. Putting that radio on the air was like a breath of fresh air. You just don't find AGC action like that in any Ham radio and the TX audio gets rave reviews from everyone I talk to with it. If I ever offer to sell this one, will someone please slap me to bring me back to my senses.
Oh, and to KM3DR, you have a rare find with the remote control handset. I wonder if that's an original or one someone fabricated. That's the one additional think I'd really like to have and will be looking at modifying one of my H-250 handsets to do this for my PRC-2000.
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KM3DR
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Rating: 5/5
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Apr 11, 2009 17:20
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Great HF Rig
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Time owned: 0 to 3 months
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After many years of searching for one at the right price, I found one Feb. 2009 at one of the Wash, D.C. hamfest unexpectally. I've been very pleased with the purchase to date. Basic HF operation on one frequency, does not perform splits. Changing freqs and modes take a little time to learn, but easy once mastered. Had success making contacts on 40 & 60 meters using NVIS, had good reports with AT-271 style whip on rig. Current draw is less that 5amps on TX. Battery pack is easy to make. Finding additional mike plugs can be a challenge. I have the standard as well as the remote mic with controls. The receive is well considering no optional filters or DSP. Can't wait until propagation starts moving up on the high bands.
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AC5XP
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Rating: 5/5
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Nov 6, 2007 18:33
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Still love it
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Time owned: more than 12 months
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Still own it; still love it.
But one interesting fact I felt is worth mentioning: In my review below (from 5 years ago) I wrote: "One wonders why such an I-Q direct-conversion concept is not used in today's DSP based radios"
Well, FlexRadio must have been listening. Their SDR-1000 and successive newer models ARE based on the same principle using a direct-conversion quadrature mixer concept, the same as what the PRC-2000 uses. Only difference is of course that FlexRadio is using a DSP for the baseband filtering (actually through your PC sound card); the PRC-2000 uses analog electronics there.
I was actually wrong about one point: It IS possible to do AM and FM in such a concept (as FlexRadio proves), AM is actually pretty straightforward, FM is a bit more complicated. But the latter is done by creating a very low subcarrier in the base-band (let's say 10 kHz) which is then frequency modulated and I-Q mixed to (from) the operating frequency. The main oscillator then compensates for the 10 kHz offset in the FM mode so it is "transparent" to the user.
It is the ultimate HF radio concept. Believe me, 10 years from now most all HF radios will be based on this method. And the PRC-2000 might have been the first one!
Loek d'Hont AC5XP
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KA4KOE
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Rating: 5/5
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Mar 6, 2005 20:22
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A good one
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Time owned: 0 to 3 months
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Bought my PRC2000 from a US Ham. These rigs are occasionally available from Combat Radio in the UK, for about 2000 US.
Set up in the back yard and worked Belgium right away on 17m.
Its a bit on the heavy side, but all in all, a great radio.
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