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1、42 Practical Wireless April 2018 E-mail: chrislorek.co.uk Buying Second-Hand with Chris Lorek G4HCL I bought my fi rst TS-700, the very second batch that had arrived in the UK (I was on a waiting list!) back when I was a teenager. As well as using it from home and mobile from my fathers car, I took
2、it down from Lancashire to my lodgings in Devon when I started studying for my degree in Plymouth. A year later, Roger Taylor G8LWV (now G4HZA), still a friend of mine, and licensed amateur Kevin (unfortunately Ive forgotten his surname and callsign) also used it with relish from our shared basement
3、 f at in Plympton near Plymouth with a 2m antenna that wed installed in our landlords loft space with his permission. I also used this in during my sandwich course commercial study training in my lodgings in Cambridge. While back in Lancashire, I had daily contacts with Rod G4BFP in Liverpool and le
4、ngthy evening contacts with Barry in Rishton near Blackburn (again Ive forgotten his callsign), both of whom also used a TS-700 and both of whom Id met and visited in their homes. The Trio TS-700 was launched in around 1974 and immediately became a hit, which explains the initial waiting list for th
5、em for UK imports from Japan. TS-700 Overview The TS-700 is an analogue VFO-tuned 2m all mode solid-state transceiver. The block diagram appears at Fig. 1. Being analogue, there are no channel memory facilities. However, there is the facility for up to 11 switched crystal control chan- nels from a f
6、ront panel rotary control. I installed crystals in mine for quick chan- nel selection of S20 (145.500MHz), S21 (145.525MHz), S22 (145.250MHz) and S23 (145.2750MHz plus my semi-local repeater on R7 (145.775MHz receive). The rig has a built-in AC supply but will also operate from 12V DC. It is really
7、a base-station rig that is primarily intended for SSB/CW operation but FM, including a 600kHz repeater offset, is available. The TS-700 covers the full 2m band in two switched 1MHz bands, with a 1kHz dial resolution. Operating the TS-700 is much like using an HF radio of its era and I suspect it was
8、 Trios competitor to the Yaesu FT-221R. In my full-time job some years later our com- panys licensed Administration Director, Sheila, had an FT-221R and when she was eventually selling it I was most tempted because by that time Id sold my TS-700 to help fund furniture for my f rst house purchase. Bu
9、t a few years later I managed to buy a further TS-700, second-hand from a semi-local seller to me, for 80, photo- graphed for this article, Figs. 2, 3 and 4. The transmitter power is 10W output, which may be rather low for todays power levels but then weve come a long way since it was made. However,
10、 its certainly enough to drive an external amplif er. The receiver is a little insensitive by modern standards too, and an add-on internal low-noise receive preamplif er is a worth- while addition. However, it is about as crunch-proof on receive as youre likely to encounter in any modern rig and pro
11、bably better than most. This is due to the very good front-end f ltering and the very clean VFO with no noisy synthesisers in this transceivers circuitry! Worth Considering If you are looking for a good 2m all-mode starter transceiver, then do consider the TS-700. It doesnt have all the bells and wh
12、istles of more modern transceivers but the price when bought second-hand is naturally far lower than newer rigs. It has a built-in AC mains power supply as well as being operable from an external 13.8V DC supply. Operation modes include SSB, FM and AM, a repeater offset, and excellent receiver audio
13、 output quality. Although it has a 1750Hz toneburst, there is no CTC- SS encode facility but a homebrew one can be added (theres a planned article on this coming up in PW from myself shortly). The transmitter f nal amplif er and receiver audio stages operate on 20V. These are generated by an interna
14、l DC-to-DC inverter circuit to obtain 20V DC from 13.8V DC. FM Transmit Audio On my original TS-700, for SSB I added an external in-line Datong RF speech processor, which helped for DX work. But on FM I still suffered from reports of quiet and muff ed audio. To improve this, f nd the C15 0.01F capac
15、itor in the micro- Fig. 1: TS-700 block diagram. The Trio TS-700 Chris Lorek G4HCL details the Trio TS-700 2m all-mode transceiver. Buying Second-hand.indd 4226/02/2018 08:30 April 2018 Practical Wireless 43 phone transmit audio section, which is fed via a series 4.7k resistor R12. Replace it with a
16、 0.001F capacitor to boost the higher frequencies as well providing a more punchy transmit audio on FM. You may, however, have to experiment with the value of this capacitor to suit your prefer- ences. I found it made a tremendous dif- ference and the f rst time I went on air with my regulars, every
17、one commented on the far better audio quality and readability. Receiver Preamplifi er As I mentioned earlier, the addition of an internal receiver preamplif er, which youll need to f t following the RX/TX switch- ing circuitry, is a useful addition. This can make a great improvement to the receive p
18、erformance. 4m (70MHz) Conversion Quite by chance while I was preparing this article, I also received an e-mail from Steve G0AIN regarding his ongoing work at converting his TS-700 to 4m (70MHz). Youll f nd details at: www.g4izh.co.uk/trio-ts-700-conver- sion-to-4m.html An Unusual Tale of a TS-700 I
19、n my f rst job in Cambridge, my f rst car, a Ford Capri 1600GT XLR (remember those?), with my TS-700 on the seat, was stolen from my works car park one lunchtime. Two youths (I still have their full names and addresses in my memory but wont name them in print because I dont know whether the Rehabili
20、tation of Offenders Act is valid from then) were caught with the car parked up and with both of them inside, just down the road from the main Cambridge police station (idiots!). My TS-700 had a Dyno-tape label (remember those also?) with my then callsign, G8IYA, stuck onto the front, and it was stil
21、l monitoring the local repeater GB3PI in Barkway, Hertfordshire. After a break following a QSO, the arresting police off cer took the microphone and called, “G Eighty One YA, G Eighty One YA, this is Cambridge Mobile Panda 21 calling”. My friend Mark G8FRL (who knew my car had been stolen) replied o
22、n air, countywide to all listening, to say that I wasnt on the air at that moment. The off cer answered via the GB3PI repeater to say that, “Yes, his car has been stolen but weve recovered it and apprehended the two people inside it. Were taking the car back to the central police compound”. “OK, Ill
23、 let him know, thank you”, replied Mark. I recovered my Buying Second-Hand month with another Buying Second-hand column. If youd like me to cover a specif c topic or equipment type in Buying Second- hand, then please let me know and Ill be happy to oblige. See you soon! car that evening, with my gra
24、teful thanks to the Cambridge police. The two youths each received custodial one-year plus committal borstal sentences after also admitting 12 other earlier TWOC (Taking Without Owners Consent) offences. Ap- parently, the police had been after them for some time. Further Information If youd like a f
25、ull user manual (2.5Mb) for the TS-700 and/or a service manual (10.5Mb), Id be happy to oblige by e-mail (see top of column). Just let me know and itll be on its way to you . Next Month Ill be back next month with a further bi- monthly Emerging Technology column with lots of new information, and the following Fig. 2: The TS-700 from the front. Fig. 3: Rear panel view. Fig. 4: A look inside. Buying Second-hand.indd 4326/02/2018 08:30
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