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| Reviews Summary for T.M.C. GPR-90 GENERAL COVERAGE |
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Reviews: 6
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Average rating: 3.7/5
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MSRP: $495.00 in 1955
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Description: 540KC TO 31.50MHZ GENERAL COVERAGE RECEIVER.
MODES OF OPRATION AM/CW/MCW/SSB.
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More info: http://www.geocities.com/tmcvintage/
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You can
write your own review of the T.M.C. GPR-90 GENERAL COVERAGE.
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W0OGH
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Rating: 3/5
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Jun 8, 2008 10:58
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Good looking radio
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Time owned: 6 to 12 months
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i bought several of these hoping to find a keeper. Fell in love with them when they first came out back in the late 50's. Thought it was the cats meow. As i said i've had several of these in the past 10 years. None still around. Most annoying was the instability of the radio. bang on the sides of it or on the top and listen to it warble and drift down the band. Visibility: gorgeous radio to look at especially when all lit up in the evening. Always fun to read the manuals. I've got other TMC transmitting equipment that i'm keeping btw. My Collins 388's, 75A-2, Sp-600 and AR-88 are much nicer radios to operate and much more stable.
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W9LBB
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Rating: 3/5
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Sep 20, 2005 10:23
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An Oldie that's only an OKie
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Time owned: more than 12 months
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I had a GPR-90 for about 8 - 10 years and used it quite a bit, mostly on 40 CW and for general SWLing.
Good points:
A Heavy Metal, Old School communications receiver built mainly for the government market. Dependable, and very seldom needed any sort of repairs.
VERY sensitive, and handles big signals well without overloading.
Quite good selectivity, assuming the IF strip has been correctly aligned, allowing the crystal filter to properly be brought into play.
Quite good audio! This one is a winner for AM operation, and especially AM broadcast band DXing.
Probably the BEST S-meter I've ever encountered on a boatanchor receiver. Once calibrated at 50 uv = S9, it tended to stay there for years and years without the need for recalibration. The meter was HONEST, and not "bouncy" like the ones on Hammarlund gear of the same vintage.
Not so good points:
Tuning dials are a bit "springy" due to the stringing technique. I was never able to cure it, even by restringing with steel fishing line. The problem appears to be that the stringing paths are quite long, and span too much distance.
It did OK on SSB, but it would have been much better with the external SSB adaptor.
The radio's frequency was somewhat drifty. For some reason, it never seemed to reach an operating temperature that it liked. It MAY be that becase the cabinet I had it in wasn't the original one temperature control and equilibrium may have been the issue here.
All in all, I found it to be a pretty good receiver, but the SP600, R390 and R390A were better overall; the GPR-90 had them both beat on sensitivity tho. The drifting problem I encountered was about the same as the National NC-170 and NC-180 that I'd had before it.
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W6LBV
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Rating: 5/5
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Sep 10, 2005 13:45
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"Scenes of my young years grow warm in my mind....."
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Time owned: more than 12 months
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I saw the new review of the TMC GPR-90 and couldn't refrain my adding my own. However, I have a slightly different version of the '90, knowledge of which may be useful to some collectors.
My TMC was obtained about fifteen years ago in a sealed-bid surplus property bid sale. As I recall, as high bidder I paid about $25 for it and then swapped out a bad rectifier (vacuum) tube, and it's been receiving without any problems ever since.
The GPR-90 is a "big iron" old-school radio, loaded with vacuum tubes and front panel controls, and it was built in an era when silicon was generally found only in beach sand. It is designed for rack mounting in standard 19" relay racks, is constructed to last "for the ages," and is almost too heavy for one person to lift. It operates solely from 120 volts a.c. It seems quite likely that mine was a sea-going receiver, possibly military but more likely riding aboard a civilian shipping or research vessel.
My radio is a GRP-90RXDS. It differs from the model shown in the photograph above by having provisions for ten quartz (receive) crystals, each providing a single fixed frequency channel. The crystals are located behind a small hinged panel in the (extended) space directly above the main tuning dials and the S-meter. A separate wafer switch, marked "HFO," provides selection of one of the ten crystals or the main VFO. The crystal holder positions in my receiver were fully populated on arrival, and the spot receive frequencies were marked in pencil on a chart located on the swing out cover. But I have not attempted to receive using the crystals. And I have other, more modern LF/MF/HF-capable receivers, leaving this one permanently remaining in my collection solely for enjoyment and nostalgia.
With a random length long wire above the roof, the '90 has exhibited good (noise-limited) sensitivity and it hauls in HF and BCB signals from around the world and the country, respectively. It does have a BFO (but no product detector) and on-board i.f. crystal filters for some selectivity. However, it is not a "modern" receiver incorporating roofing filters and DSP processing, and it cannot be used for reception of Amateur DX contest pileups or for separating two CW signals that are only 150 Hz apart. It also does not have the "top of the field" elegance of R-390s or Collins receivers of that era. But the work that it does, it does quite reliably. If you are interested in "vintage receivers" of an earlier day and have the opportunity to buy one inexpensively, you can have a bit of fun with it and learn something about the history of electronics technology.
My favorite use for the receiver is to listen in the evenings to the BBC World Service Carribean relay on 5975 kc/s (not "kHz," which designation was not yet in use when this receiver was built). With the i.f. selectivity set wide open, the AGC and ANL turned off, and the AF gain fully advanced, I back off the RF gain pot to reach a comfortable listening level. The receiver is connected to an eight inch full range speaker in a good enclosure (the GPR-90 has no internal speaker). Broadcast-quality audio floods my office/shack, sufficiently good to fool my wife once into thinking that she was listening to a local AM radio station.
This was a rugged receiver manufactured for serious commercial purposes. It was never intended to be equivalent to a Grundig or Sony solid-state "all band" consumer portable, nor to equal the performance of a modern Watkins Johnson monitor. But it did its job well, for many years. If you approach it with this understanding and don't bemoan its omission of "modern features" such as, for example, lack of an RS-232 port on the rear panel, it is well worth having.
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WB6MYL
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Rating: 3/5
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Sep 10, 2005 11:34
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ONLY OK
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Time owned: more than 12 months
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I, too, wanted to like this receiver; anything by TMC has to be high-end for its time? it was a nice looking receiver that had average performance. I didn't think it was that selective or sensitive; did sound very good w/ the TMC 591A SSB adapter but the 390A, Racal RA-10, 51J-4, and SP-600 ran circles around it. It was one of my few receivers I have actually parted with. Regards, Phillip W. Harris, PhD.J.D.P.C.
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WB8UHZ
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Rating: 5/5
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Sep 9, 2005 19:39
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good radio
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Time owned: more than 12 months
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Well built , great audio, needs some improvement in selectivity, but can be adapted, improved... had this one for better than 10 years... get one if you like great older radios.
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WA3VJB
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Rating: 3/5
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Aug 22, 2003 16:53
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Disappointment
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Time owned: more than 12 months
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I really tried to like this receiver, but I've just let it go in favor of a Hammarlund SP-600.
The main problem when using the GPR-90 to receive AM on the shortwave ham bands is that the only useful bandwidth is the selection for 10Kc.
This is too wide during times of band congestion, and too narrow when band use is low. Mostly, I enjoyed it on 10 meters AM during Cycle 23.
Attributes include nice sounding, low distortion, speaker-level 6V6 output. Also, this is a very pretty receiver, with symmetrical dials for bandspread and main tuning. It's built well, but not really hefty like military standards. It is built better than amateur-grade alternatives such as those among the Hallicrafters line.
My purchase was more from nostalgia than functional strength, and I knew it was coming up short when I ended up gravitating more toward my R-390, R-390A, and HQ-100A.
Paul/VJB
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