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Reviews Categories | Transceivers: VHF/UHF+ Amateur Base/Mobile (non hand-held) | Kenwood TR-7400A Help

Reviews Summary for Kenwood TR-7400A
Kenwood TR-7400A Reviews: 24 Average rating: 4.7/5 MSRP: $399.00
Description: Early Synthesized 2 Meter Mobile Rig
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K5EGG Rating: 5/5 Feb 10, 2013 16:52 Send this review to a friend
Great tinkering radio  Time owned: more than 12 months
I own two of these, and have only been a licensed ham since 2009. I purchased my first one off ebay for $9, listed in the CB section, as 'non-working'. The previous user(s) had done some horrible things to this radio, the worst two were butchering a data interface to it, and leaving it in a humid environment (like a junk car interior in southeast Texas) for many years. After a couple hours on a very 'noob' bench, I had this thing working like a charm.

Second unit I got for about $30 off a "poor quality" listing on ebay that received very little attention.

Both units have been absolutely rock solid despite many noob mistakes (TX with no antenna, APRS automatic interface freezing leaving the radio in a TX state for several hours, etc) they keep working.

The best part about this radio is most everything is discrete components, and of the few ICs only a couple are proprietary. With any sort of 'electronic clue' one can keep these radios in a functional state forever.

If you want a modern unit with memories and an adjustable CTCSS generator built in, look elsewhere!
K2SNY Rating: 5/5 Dec 19, 2011 17:39 Send this review to a friend
Just picked up!  Time owned: 0 to 3 months
I just received my kenwood tr-7400a in the mail today. I bought it off of ebay for $27.00 and it works great!
I am in love with this little old radio!
best $27.00 I ever

AC8DE Rating: 5/5 Mar 30, 2009 13:29 Send this review to a friend
Rock Solid  Time owned: 0 to 3 months
When this radio was originally produced in the mid '70's, I was 14 years old. I bought this unit for $20 from a buddy's brother who needed the money and wasn't sure of it state of operation, along with some other equipment. It had been VERY clumisily surgically altered because they lost the 2-pin power connector.

I took to refubishing the radio right away, as I could tell it was really solid just by weight alone. I found a power connector and and took to reversing the ugly "modification" power conenctor job. It also looked like it had been stored on the bottom of a dung heap, had evidence of some water being in it and reeked of 30 years of smoking... BADLY! Even a smoker would have been offended. After a full dissassembly, going through some solder, a full can of contact cleaner to clean its guts, replacing the indicator bulb with a LED and resistor and spending about 2 hours giving it a clean with a half box of Q-Tips, the old girl looked pretty darn good. A bit scratchdd on top and bottom, but the face still looked pretty good. I put power to her in my shack and she fired right up, so off to my my local repeater I went. The sound quality reports I got from my friends was nothing short of perfect. Everyone was in disbelief that I only paid $20 for this old radio. So with all that abuse and lack of care, this radio still worked perfectly. Again, what does that say about the build quality of it? I only have one segment of one of the 7-segment LED's out of the front, and even then only intermittently, which is amazing considering this is the known weak link of this radio. Perhaps I'll get back in there one of these days and hard wire it to fix the issue, when I get a wild hair. I might even add the Com-Spec tone card to it with a proper modification to hit the local repeater that use tone. I must admit, I do like this old radio and intend to keep using it as my primary 2M rig in my shack.
W2KG Rating: 5/5 Dec 6, 2008 10:31 Send this review to a friend
Excellent rig!  Time owned: more than 12 months
I bought one of these when they were new in '78 and later sold it to buy some other toy. I suspect that if I'd kept it, it would still be ticking along. Nevertheless over the years I've bought two of these used and they're still cooking just fine. No need to echo what others have said about ruggedness, etc. The great beauty of this rig in my opinion is its SIMPLICITY! Of course, in '78 we thought it was real complex! I would recommend it to anyone who hates those bloody menus on the new rigs. Just invest in a little Communications Specialists TE-32 tone box and you can go anywhere with this rig. I might even buy a third one by the time I'm done, if I can talk the XYL into letting me get a pickup to go along with rest of my "fleet".
KC9MLL Rating: 5/5 Jun 1, 2008 14:27 Send this review to a friend
Solid as a rock!  Time owned: 6 to 12 months
Kenwood made a great radio when they designed this one!

I am a relatively NEW HAM, and I borrowed this rig from my sister.
It was originally owned by our mother. (SK)
Anyways, it runs great! Only thing I had to do with it, was replace one Diode and Clean the mike. It was nasty, and mom was a smoker.

The DOWN SIDE: The Tone Board was an after market installation , and it can only be set to one tone at a time by flipping dip switches on it's board.

Really a rock solid rig, and would definately be worth hunting one of these up at your next HAMFEST! Makes a Great every day rig, and a Solid backup!

Kenwood Keep up the great work!!
N7TRZ Rating: 5/5 Apr 15, 2008 14:54 Send this review to a friend
A venerable battleship  Time owned: more than 12 months
I have owned three of these over the years. I've sold one to a new ham that had display troubles, since the selection method needs no display to determine what frequency you're on. I've also given one away to a blind ham, since the selection method also allows click counting and has positive stops at the zeroes. If you are unsighted, or working in the dark and "get lost", all you have to do is spin the knobs to zero and re-count the clicks. This arrangement is also great in a vehicle. No need to look away from the road to QSY.

The last 7400 I bought was an estate find several years ago that was positively pristine. I ended up paying $100 for it, but that was before the IC-2200 could be had for $160. No scratches, chips, scrapes or outages. This is my keeper.

The display on these is the weak link in that there are numerous plug-in connections involved. The 7400s with more use I've owned both had some problems in this regard. I've found a film of silicone grease on the contacts to keep the air away from them can keep them working a long time, but the contacts seem to lose tension after a few years and this makes them finicky. Replacements can still be found in the appropriate catalogs or online.

The robustness of this radio is otherwise outstanding. I completed the effect by ditching the stock mic to emergency duty and wired up a vintage Shure unit to replace it. You could use either as a weapon now and still rely on this radio to be in working order.

The heatsink is massive and long winded QSOs barely warm it during the warmer months. All devices in the amp section appear to be discrete so no worries about blowing a hybrid.

I personally don't find a compelling need to tone this radio in my area. Not many machines require it, and the receive is so interference free I don't bother worrying about tone squelch. My later rigs all have CTCSS if I need it.

Should two meters be narrow banded, it appears this radio could be entirely refiltered with little effort. Communication Specialists carry many possible replacements.

I do plan on passing this rig down to my kids or grand kids. A true classic right up there with the FT-101 and the Memorizer.
N4EDX Rating: 5/5 Mar 10, 2008 20:33 Send this review to a friend
Awesome Old Rig !  Time owned: 0 to 3 months
I found one at the Charlotte Hamfest this past weekend.. missing a power cord and mic, fixed up both with a new cord and an old MC-43 hand sqezer
.Fired right up ! noticed the meter lamp has burned out, 20 minutes later I that fixed.. I love this thing, the weight, size and build reflect the old quality not seen today.
32 years old and sounds and receives better than the new stuff.
W8ZNX Rating: 5/5 Jan 22, 2006 12:12 Send this review to a friend
heavy duty  Time owned: more than 12 months
Bought my TR-7400A new over 30 years ago
was driving tractor trailer for a living
this radio has over 1,000,000 hard truck miles
day in day out use for over 12 years on the road, in all kinds of wx and
and all kinds of tractors
some times changing truck every week
if one year of hauling steel
in a R model Mack with camel back suspension
could not shake it to pieces nothing can!

yes sometimes the digital read out would
stop working but just bang hard on the
top and it works

looks like it's been in a war
dented, banged up, paint wore off most
of the bottom and top

got more use out of this one radio
than any 4 other radios ive ever owned

dit dit Mac w8znx

AC5XP Rating: 5/5 May 12, 2005 14:22 Send this review to a friend
Classic VHF radio, built like a battleship  Time owned: 0 to 3 months
By: Loek d'Hont AC5XP

The RT-7400A is a two-meter FM transceiver that stems from the early eighties. It covers 144MHz to 148 MHz. It was the successor of the Kenwood TR-7200 (sold in the US as the Drake TR-72) and competed with Yaesu’s FT-227R. It must have been one of the first synthesized VHF rigs that Kenwood has produced (the TR-7200 was a crystal controlled radio)

The first thing one notices when looking at this radio is the way the frequency is set, which is very basic indeed.
There is a control for each digit; one switch sets the MHz selection, one for 100 KHz, 10 KHz and a push button to toggle between 0 and 5 kHz. This might look primitive today but you have to look through 1980 glasses: This was a huge leap forward from the crystal-based radios, every frequency could be set with crystal stability without the need for additional crystals.

Subsequently, there are no memories. Repeater offset is done with a separate 3-position switch.
Because of this concept, at first glance the radio almost looks like a military radio. When one looks a bit deeper it turns out that there is a diecast front panel, aluminum machined knobs and an over-all feeling of robustness. All of which makes the military impression even stronger.

When one lifts the hood, the construction turns out to be superb. Everything is easily accessible and well organized inside the case. Wiring is kept to a minimum and neatly laid-down. The synthesizer section is easily recognized from the RF boards.
What catches one's eye is the 3-stage helical filter to keep the "out-of-band garbage" away from the mixer stage. That they don’t do any more in today's radios! Not only because it is too expensive, but also because we all wanted "general coverage" receivers for our ham radios, preferred is DC to daylight….

It always strikes me how much the Kenwood and Yaesu radios of the era look alike from the inside. Same construction techniques; same type of wiring and same component vendors. Even the way the synthesizer is separated from the main unit and done on FR-4 boards (where the RF boards are on phenolic boards) is identical. I'm almost sure the radios actually come from one and the same manufacturing company. Who knows.

Conceptually the radio is straightforward and offers little surprises. The master VFO is the synthesizer. The latter is built around the venerable MC4044 phase-frequency discriminator. I don't know who invented this circuit (it doesn't bear anyone's name) but whoever it was sure deserves a Nobel price, hi. The MC4044 is a difficult to get chip nowadays but the digital circuit is used in every VLSI synthesizer chip ever made.

The programmable dividers of the time did not like frequencies much higher than 10 MHz so a mixing scheme is used to mix the VHF VCO down to this frequency range against a fixed frequency from a crystal driven stage. The stage actually deploys 2 crystals which take care of the 0 and +5 kHz offset mentioned earlier. That also means the synthesizer's smallest step size only has to be 10 kHz, not 5 kHz.
The +600 and -600 kHz for repeater offset is actually created digitally (by offsetting the digital code for the programmable divider) which is unusual compared to contemporary radios. This was in fact the only surprise I could find in the design.

The RF section is straightforward; receiver starts with a dual-gate MOSFET RF stage and mixer, with the earlier mentioned helical filter in between the two. First IF is 10.7 MHz which passes first through a monolithic crystal filter and then through a 10.7 MHz ceramic filter. Then the signal is downmixed to 455 kHz where the "main" IF filtering is done through a solid ceramic filter. Limiter, discriminator and AF stages are all done discrete. Actually, apart from the synthesizer stage (which is built around TTL and CMOS off-the-shelf chips), there are very few ICs used in this radio. This is a big advantage if something goes defect; you won't have to start looking for an incredible difficult to find custom chip when parts need to be replaced. Everything is still available albeit a bit difficult for the earlier mentioned MC4044 chip.

The transmitter starts with a crystal-based 10.7 MHz oscillator which is FM modulated. This is than mixed against the synthesizer signal which yields the transmit frequency. The signal is amplified and filtered. The RF amplifier is quite beefy for the era; a hefty 25 watt is produced; contemporary VHF radios of the time were more in the 10 watt range.

How does the radio work? No complaints here. The receiver can compete with anything on the market today. Not once have I noticed an intermodulation product from paging towers (or maybe these towers are all turned off nowadays?), the helical filter seems to do its job. (FYI, the manual calls this a "Herical resonator", I have found the translation to be poor. In the area of manuals Yaesu was clearly superior.)

The transmitter has excellent modulation, and the 25 watt RF output can be burned over a prolonged time due to the heavy heatsink.
The frequency readout uses large 7-segment LED displays, even the first two fixed digits are shown (this is where Yaesu got cheap with the 227). One has no problem reading these. The S-meter is clear and bright. The controls have a logical lay-out and feel solid. People with thick fingers won't have a problem operating this radio, that's for sure.
On the back, there is a two-prong DC connector, the same as on the Yaesu FT-227R. But the polarity is reversed with that radio! It is a bit silly that the two manufacturers could not agree on harmonizing this. Furthermore there is the inevitable SO-239 "UHF" connector and a jack for an external speaker. On the side of the rig there is a connector for an (optional) external DTMF keyboard. On that note (no pun intended), the radio allows for optional PL tone filters to be installed but this would be impractical in today's repeater environment because you would only have a single, fixed set of PL tones. The latter is the only thing that prevents you from using this radio the way you would use a modern rig: No PL tones. One way to fix this would be to connect the radio to a switchable off-the-shelf tone generator via the DTMF connector, this should be very do-able because the connector also offers DC voltage available during transmit.

Another thing that is worth mentioning is the microphone. This is a very sleek and small unit with a nice working PTT switch and a large element (it is not an electret mike, although one might think so judging the over-all size).

To summarize, this is a very robust rig with excellent radio characteristics and equipped with no-nonsense controls. What I almost like the most on this rig is it’s "face": I really like the military look and feel. But in all fairness, all radios of that era were lookers. Maybe I’m getting old but today’s "organically shaped" radios just don’t do it for me.
Get yourself a TR-7400 – A great and classic collector's item!
KA4TWK Rating: 4/5 Feb 26, 2005 07:36 Send this review to a friend
+++Try a MC-50 Mic +++  Time owned: more than 12 months
I have had this unit for many many years. Don't even remember when I got it. The stock Microphone has never been an outstanding preformer. Fellow Hams have always said the stock mic made my voice sound tinny. I recently came across a used MC-50 Mic and have begun using it. It plugged right in with no modifications. The audio reports are now outstanding. I use the unit as a base rig and have the local tone board installed. Excellent rig and simple to use. With the MC-50 mic, it is even better. Bill ka4twk South Carolina
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