Drake_TR-6_review_1974.pdf

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1、features of current am Drake TR-6 5O-MHz Transceiver W I: E TEND to think of a sideband transceiver as an isolated piece of ham gear, useful mainly on its own, or perhaps as a driver for a linear amplifier. The Drake TR-6 has just about every imaginable operating feature. either built-in or availabl

2、e as an extra-cost option, and it also makes provision for use with other units of a multiband amateur station. Thus. the vhf-oriented amateur can use this major item of his station is the nucleus of a plan for the future. adding accessories and optional operating conveniences as his needs and perso

3、nal finances dictate. Of course Drake has its own gear in mind for much of this, but the fellow who likes to do some of his own building will Iind attractions in the TR-6 versatility as well. He can start with the “basic” TR-6, with or without its power supply, speaker and other primary operating ac

4、cessories. For home-station work he will probably want the Drake AC4 Power Supply. He mav already have it, as it is used with other Drake items. For mobiIe operation he can add the DC-4 supply. to work from the car battery. (Drakes AC-3, DC-3 and DC-24 supplies. the last for 24-volt service. are als

5、o suitable with the TR-6.) At this point our hero has a 50-MHz transceiver capable of 300 watts PEP input on ssb or a-m. and 260 watts on cw or fsk His receiver sensitivity is all he could ask for. and the selectivity is optimum for 50-MHz ssb. If he expects to work a-m or cw extensively, his next s

6、tep will probably be plug-in filters for optimum selectivity for these modes. 6 kHz for a-m. 2.4 kHz for ssb. and 0.3 kHz for cw. A special filter is needed for lower-sideband operation, but since nearly all 6-meter work is upper-sideband. this is a lower-priority option. Frequency coverage of the T

7、R-6 in this form is 49.9 to 51.0 MHz. Other overlapping 600-kHz tuning ranges can be provided for a total of nine 500-kHz segments from 49.5 to 54 MHz, with plug-in crystals available as extra-cost options. Activity is concentrated mainly near the low end of the band, so these can wit for more urgen

8、t acquisitions. to be described later. One difficulty with most ssb transceivers, for vhf operation at least. is being limited to working stations on ones own frequency. The transceiver has been a major cause of QRM problems in the vhf bands. These bands are wide enough to support an enormous amount

9、 of activity without serious interference, were it not for the channellization that the transceiver encourages. The TR-6 system offers a way out of this. With the Drake RV-6. or your own remote VFO. you can control either the transmitting or receiving frequency. or you can switch the VFO off and go

10、over to normal transceiver operation, when it is desirable. Similarly, the Drake Model FF-1 Fixed-Frequency Adapter allows crystal-controlled operation of either the transmitter or receiver. A 14-MHz input-output jack on the TR-6 opens up options such as external vhf or uhf receiving converters. ext

11、ernal receivers. and heterodyning units for using the TR-6 features on other bands, from hf to uhf. The equipment can be used with 2-meter transverters. Drake- designed or otherwise. If mobile operation with the TR-6 is planned. the Drake Model 9-NB Noise Blanker is a must. This mounts inside the ca

12、binet bv merely plugging in. and Its operation is provided for on the front panel. The MMK-3 Mobile Mount will very likely be needed. as well. A simple but handy option for the home-station operator is an assortment of mounting feet. permitting horizontal positioning. or two setting of upward tilt.

13、How It Works In this writers opinion the TR-6 is a complex piece of equipment. and the purchaser may have some difficulty understanding its basic functions when reading the instruction book. Its 57 pages of text are not readily digested. even by the experienced reader, and its block and schematic di

14、agrams are understandable only after intensive study. To the uniniated. the complex schematic presentation is likely to remain a mass of long parallel lines, and innumerable cross-overs. Admittedly a simple description of this sort of equipment is not easy. and the block-diagram approach may leave i

15、ts user open to charges of over-simpfification. The TR-6 book does have the information. which is more than can be said from some manuals, even if it is not in the most easily-read form. In our block diagram. Fig. 1. we have tried to clarify stage functions and signal paths by separating the transmi

16、tting and receiving elements, insofar as possible. When the same stage or component is used for both purposes. it is shown twice in our diagram, or drawn in broken lines, or both. We have deliberately left off type numbers of tubes and transistors. since they tend to be of minor importance to the ca

17、sual reader. 54 QST n.rm Y %i+,MNt- 14.5Yrn r -( SuETm 1; 2i I I 02 ; I I I ?lo . 4.9 m A V C AM? RECEIVING TO ANT. RELIT w Y 8 WC Vi6ANP VOX V9 A M P Fig. 1- Block diagram of the Drake TR-6 transceiver, showing principal receiving and transmitting functions. Several of the 19 vacuum tubes, 13 trans

18、istors and 12 diodes are not shown herein, in the interest of clarity for major functions. Similarly, the component type numbers are omitted from the drawing. I1 BUFFER Fig. 2 -Principal details of the PTO and buffer on the Drake TR-6. Values of Cl and C6 are selected during production, to achieve t

19、he best possible dial calibration with a given tuning assembly. The PTO covers 4.9 to 5.5 MHz, and is driven by the main dial. Its frequency is shifted automatically in changing modes, with external circuitry not shown here. An fsk voltage can be fed into the jack so marked, for transmission of RTTY

20、 information. Note the low-pass filter in the buffer collector circuit, to keep harmonics out of the following circuits. July 1970 55 T ANT. R ELAY RF AMP MIXER T AS INDICATED. DECIMAL “ILVES OC CAPACITANCE ARE ,N Y,CNOA”AOS , yF, ; O T H E R S ANE IN PICOFARAOS (PF ON yyF); dcC,., Lo, SNlTcnf LI NL

21、 RESISTANCES ARE IN OHMS;A7 L .lOOO. UlOOO000 The TR-6 can be thought of as a 14-MHz ssb rig, with transverting circuitry to make it work on the 50-MHz band. To generate a 14-MHz ssb signal it uses the popular 5 + 9 system, the central clement of which is the transistorized permeability-tuned oscill

22、ator (PTO) covering 4.9 to 5.5 MHz. This is driven by a smooth-working and well-calibrated main dial. Permeability tuning has advantages, but it has not been used extensively by home-builders of ham gear. A look at the simple schematic of the PTO in the TR-6, Fig. 2, may encourage gadgeteers to atta

23、ck the not-too-formidable problem of moving a core into and out of a coil. If you decide to try it, use this hookup, not the one shown in the TR-6 manual. The draftsman responsible for theirs made the classic error of grounding the high side of the dc supply for the PTO. The cascade rf circuits of t

24、he receiver front end are shown in Fig. 3. It has elements of interest to the vhf converter builder. Note particularly the F i g . 3- T h e r e - ceiver front end of the TR-6 uses a cascade rf amplifier circuit. Parts la- belling is the same as in the Drake manual. Note the impedance matching in the

25、 input circuit, the fixed ca- pacitive-bridge neu- tralization, and the bandpass interstage coupling. External control and power circuits were omit- ted in the interest of clarity. impedance-matching front end, L10, L11 and C120, and the neutralization by means of the fixed capacitive-bridge network

26、, C299, Cl92 and C298. Details of the agc and switching circuits are omitted in this diagram in the interest of clarity. The interstage coupling circuit consists of T17, a shielded rf assembly, C188, L15, and its series capacitors, Cl49 and C295. The injection oscillator, Q7, has nine crystal positi

27、ons (two crystals supplied) for frequencies in 500-kHz increments, from 35.5 to 39.5 MHz. (13.9 MHz below the low ends of the nine overlapping tuning ranges, each covering 600 kHz.) The first-intermediate-frequency signal, 13.9 to 14.5 Mhz, is then fed to a second mixer, V3, which is the first vaccu

28、um tube in the receiver lineup. The tunable-oscillator energy beats with the signal to produce a 9-MHZ output, which then goes through the i-f filter, labelled FL1 in Fig. 1. The actual frequency of this filter depends on whether it is to be for a-m, usb, lsb, or cw. Two 9-MHz i-f amplifier stages,

29、V1 1 and V12, feed either a product detector, V16, or the a-m detector, V2. The audio output of either is then amplified in V17. The PTO is the primary frequency-control element of the transmitter portion as well, the heterodyning operations taking place in reverse order when transmitting. At the lo

30、wer left of Fig. I, we start with the VOX system and the speech amplifier. The audio voltage and the energy from the 9-MHZ oscillator, V16, are combined in the balanced modulator (4 diodes). The resulting double-sideband signal is amplified in V15 and then fed through the previously-mentioned i-f fi

31、lter. Output of the filter is in the final form that Interior of the TR-6, with the Noise Blanker installed. Transmitter output stage, with three 6JB6 sweep tubes in parallel, is at the lower right. The PTO, driven by the vernier dial, is in the upper left corner, with the noise blanker directly bel

32、ow it. The plug-in filters for a-m and cw bandwidths are in the upper center. 56 QST for the on-the-air signal will take. except that it is on 9 MHz. The PTO, the 9-frequency crystal oscillator, and two mixers, V7 and V4, convert the signal to the 50-MHz band, whereupon it passes to the driver, V6,

33、and final amplifier. The output stage uses three sweep tubes, V8, V9 and VIO, in parallel. Amplitude modulation, when used, is supplied to the screens of the sweep tubes from VI 4, resulting in controlledcarrier operation. Operation For all its complexity, and to some extent because of it, the TR-6

34、is surprisingly easy to operate. Adjustments usually made in sideband rigs when changing modes are taken care of automatically. The operator can easily switch between ssb, cw and a-m, and be tuned up for optimum results on each mode. This is a far cry from the procedure that must be followed with so

35、me ssb layouts, including the writers. If the initial tuneup is done according to the very simple step-by-step procedure given in the manual, signal quality will be good in all positions, and voice levels will he close to optimum for best readability. In considerable operating experience with the TR

36、-6, we have found only two points which require careful attention. One is that the load the transmitter “sees” must he close to 50 ohms, or you can run into trouble quickly with final-tube Bottom of the TR-6, with the final amplifier stage deterioration. Sweep tubes are relatively inexpen- in the lo

37、wer left corner. Jacks for phones, key and sive, and they work well in linear-amplifier service, microphone are along the right side of the chassis, as are controls for VOX, antivox and Smeter zero but they are not tolerant, if operated near their adjustment. The power source plugs onto a fitting ma

38、ximum ratings. for extended periods of time. on the rear wall. The socket in the upper With the TR-6, you watch your SWR - or,else. right-center is for connecting the remote vfo, if And you dont just run to the nearest radio or TV used. Plug-in crystals and their range-selector store and buy three n

39、ew tubes if you damage the switch are in the upper left-center. originals. With three in parallel, the tubes must be encountered make this statement seem a hit on the optimistic side. A little carrier is not important in of nearly identical characteristics, or youre in for weaksignal ssh work, and i

40、t may even help some trou hies. fellows you work to tune the signal in properly, but appreciable deterioration in carrier balance can bring on undesirable signal characteristics with the The other point concerns carrier suppression. TR-6. Especially if youre working locals, your carrier becomes very

41、 obvious in the form of a The manual says “The carrier balance control is hummy background on your signal, if the balancing adjustment is not “right on.” The factory adjusted, and should not require resetting automatic level control in the TR-6 is effective in holding peaks down, and average level o

42、f audio up, under most conditions.” At least two TR-6s weve hut with appreciable carrier the modulation caused by noise and hum can be objectionable, over high-signal paths. easy mode switching is expecialiy nice, and the cw performance should do much to encourage the newcomer to the 50-MHz hand to

43、make use of this rejection in the early minutes after turn-on. Wed much-neglected mode. The shaped keying results in a fine cw signal on the air, and the automatic recommend the half-hour warmup beforeoperating, sidetone gives the inexperienced cw operator great assurance and helps mightily to impro

44、ve his fist. wherever possible, as well as before adjustment. This is a feature long overdue in 50-MHz stations! From the standpoint of operating convenience and effectiveness in making contacts, using the TR-6 is a very pleasant business. The quick and The writer used the TR-6 extensively in variou

45、s kinds of operating, and found its versatility and almost foolproof adjustment provided a new measure of satisfaction and pleasure in 50-MHz multi-mode work. Its effectiveness in the heat of the 1970 ARRL. VHF Sweepstakes was particularly noteworthy. The cure is careful attention to the carrier- ba

46、lance adjustments, not only the control so labeiled (R185, at the rear of the chassis) hut also C127, alongside it. The book cautions against nulling the carrier before at least a half-hour warmup. We found this point to be deserving of emphasis. Though the TR-6 is very stable as to frequency, there

47、 is a marked change in carrier Theres always at least one “hut,” it seems. The writers one gripe regarding operational aspects of the TR-6 is that in going from sideband to a-m, you have to go through the cw position on the mode switch. in order for the TR-6 to operate in the other modes the keying

48、jack must be closed, either by its own normally-closed contacts, or hy those of a key plugged into the jack. With the July 197057 mode switch in the cw position, the signal goes on the air when the jack is closed. Thus you cannot switch from ssb to a-m, or back again, without putting a burst of cw o

49、n the frequency. During the VHF SS, for some hours we wondered about the beeps we often heard when we snagged some of the more difficult Sections, until WC suddenly realized that they were produced by some of our TR-6-using competitors, moving in for a shot at the new multiplidr, and switching modes! The description of the TR-6 given here is by no means complete. Rather, we have mentioned mainly those items in which this equipment is unusual or unique. Just about every other feature normally found in hf sideband gear is included in the TR-6. Operators who have had experience with other