| AC5XP |
Rating:      |
2008-05-26 | |
| Yaesu's number-one classic! |
Time Owned: more than 12 months. |
The FT-902DM radio I think is Yaesu's #1 classic. It basically is the last of a family of radios that started with the FT-101 and went on in evolution through the FT-101ZD and the FT-901. As such, it is the last and best of its class. It actually is much better than the FT-One which came out later after the FT-902DM.
The 902 looks like the 901, but it differs from that radio in major aspects. The most important improvement that the 902 offers over the 901 I believe to be the improved receiver front-end, which was already pretty good in the 901, that one being the first to use a double-balanced mixer. (The 101 series only used single-ended mixers in the receiver front-end, using a dual-gate MOSFET).
Everything on the 902DM radio works very well and as such it is a pleasure to operate. Also from an ergonomic standpoint Yaesu did a good job here. Large knobs well laid out on an aluminum diecast front panel complete the impression of ruggedness.
The digital readout will require calibration when you buy this radio used, but once you have done so it stays very constant. Which is actually strange because the radio uses the same frequency counter board as the FT-107M and the FT-707 but for the latter radios the counter drifts about 200 Hz from warmup. On the 902 I have not noticed this, maybe a better quality of crystal was used for the counter board.
Just to make sure, I’m talking about the frequency counter accuracy, NOT the VFO stability because the latter drifts much more from warmup, about 400 Hz. But that is easily compensated for by adjusting the radio dial back to the correct readout. When the counter drifts however, this error cannot be compensated for, so that is why it is so important that the counter time-base is drift-free.
All boards in this radio are of the plug-in type. Nice to quickly replace a board but not so nice if you need to work on them because you will need extender cards which are not easy to get.
What is really neat on the 902 is the memory feature. Nowadays memory features and second-VFO capabilities are easer than 1-2-3, one just stores the frequency code for the digital synthesizer in as many memory registers as one wants. But in the days of the free running VFO’s (as the 902 has), this was much more difficult to accomplish. Yaesu basically solved the challenge by measuring the 5 MHz VFO frequency in a counter, and using the counter result as the frequency code for a second VFO based on a digital synthesizer that spans the same range as the main VFO (5.0 MHz to 5.5 MHz) In this way, a particular set VFO frequency can be memorized and reproduced by the synthesizer. Now you also will understand why this only works within a set band; because the master VFO is re-used for each band. As an example; suppose you memorize 3.800 MHz; then on 40 meter the memory channel results in 7.300 MHz, on 20 it would be 14.300 MHz and so on. That is also the reason why cross-band splits are not possible in this concept. But within the same band it works well.
For the 902, the synthesized memory VFO uses a very low step-size (100 Hz resolution) which results in a very slow settling time (several seconds) because of the low cutoff frequency for the loop filter (probably less than 10 Hz) combined with the fact that this is only a single-loop synthesizer. But it works well, albeit without the possibility of a memory RIT function; what you store is what you get, rock-solid but nothing more.
The same memory concept is used for the FT-107M and the FT-707 external VFO. But for the FT-107, it was implemented slightly different; there the resolution is 1 KHz where the 100 Hz steps are made outside the PLL (by pulling the reference crystal). As a result, RIT is possible but synthesizer over-all stability is heavily compromised. I therefore prefer the method used for the 902.
The FT-707 digital VFO has this implemented the best though; it uses a two-loop PLL capable of making 10 Hz steps without the need for shifting crystals. As a result, this synthesizer is fast with a high resolution while maintaining stability. But at the cost of added complexity.
Back to the 902. I really have nothing bad to say about this radio because everything works well. The receiver uses a manually tuned front-end which, in combination with the double-balanced mixer yields an excellent near-frequency rejection of unwanted signals.
And because it is a single-conversion receiver, the IF crystal filters ARE the "roofing filters", the latter concept a popular advertisement slogan for today's radios. Let's not forget that "roofing filters" became a necessity because of the general-coverage up-converting receiver concepts that became so popular soon after the 902 saw the light of day.
Another nice touch on the 902 is the variable IF filter concept which works very well. One really would not need the optional 500Hz filter because of this. Just to be clear; this is NOT a simple IF shift. It is a true variable IF setting which is done by letting two sharp-edged crystal filters "run into each other" (an old Collins patent who used the concept extensively in its high-end receivers)
By the way, the same concept is used for the FT-107M and the FT-707, as the latter radios share a lot of DNA with the 902 and are clearly designed by the same Yaesu engineers who did the 901/902.
Another great feat is the tube PA, with 6146 tubes, thus abandoning the sweep tubes as used for the FT-101 series. Sweep tubes seemed like a good idea at the time due to their abundant availability for the TV market, but when the 901/902 were released that was not the case so much any more. We have to thank Yaesu for that decision because the 6146 is still easy to obtain in today’s markets, where this is much harder for the sweep tubes.
What else can I mention? The excellent speech processor; the very well performing AM and FM modes; the high quality of build; just to name a few.
And last but not least, this radio really LOOKS and FEELS like a HF transceiver. This in contrast to today, where radios apparently all need to look like something that walked out of Darth Vader’s living room, in an attempt to appeal to the X-Box generation…
73s, Loek "Luke" d'Hont, AC5XP |
|
| M0RTS |
Rating:      |
2007-07-25 | |
| Great Example of its time |
Time Owned: more than 12 months. |
I have owned one of these gems for 8 years now since i have been licenced.
Transmit reports have always been cracking with excellent audio,have heard this radio on the air when it was on loan to another ham and could not believe what i was hearing. The reciever is sensitive and pulls in the weakest of signals.My friend who borrowed this beast went out and purchased one himself.
I run mine with the matching accessories i.e External VFO,ATU,2m/6m/70cm transverter and monitor scope. All works well especially transverter 10watts output on 6 metres is great as is 2m and 70cm for local ragchews.
Very reliable and built like a tank, cannot justify buying new radio with bells and whistles when this one is more than adequate.
Only snag is that the line up is very bulky equipment but we can make an accept this as these radios were not built in recent years. If anyone needs a radio to get on to HF i would suggest this one anyday of the week. If you have no experience of plate and load this may be slightly different at first but performs just as well as any modern rig.
73 |
|
| GM0ELP |
Rating:      |
2006-12-30 | |
| Good, reliable fun |
Time Owned: 3 to 6 months. |
Having read all the reviews, I just had to have one ;-). I was now looking for a miracle in terms of performance and definitely didn't get that in comparison with modern day radios such as FT1000MP MkV (no big surprise). However, it has a very sensitive receiver and comes with some nice extras which seperate it from similar older radios.
The APF feature is a joy for CW ops and just seems to 'pop' the wanted signal out whilst rolling off all the background hiss.
The width control allows interference handling cabability for SSB and CW contacts, although even a small change in this control will result in noticeable attenuation to the wanted signal.
The on-board keyer is great although I found I couldn't send a 'C' without waggling the paddles instead of just squeezing (I'm used to Iambic B).
The single memory allows QSX and quick QSY without the use of XIT/RIT which is handy for working the occassional DX.
RX audio is very rounded making large signals sound great, but I found it difficult when working weak stations and found myself swapping to the MkV or the IC751a.
This must have been a radio to be reckoned with in it's day and still holds it's own today as a useful, fun, reliable hybrid for those of us who like rigs that glow in the dark.
It's very easy to tune and has a nice feature that releases the PTT after a predetermined period to prevent damage. This probably explains why these radios are so reliable.
I've given this radio a 5 not for out and out performance but for it's reliabilty and extra features which make it a useful radio even by todays standards.
If you must have a valve radio then give this one serious consideration.
|
|
| KB0HAE |
Rating:      |
2006-12-12 | |
| The BEST Yaesu radio ever! |
Time Owned: 3 to 6 months. |
| I owned one of these great radios for about 4 months. It is the BEST radio Yaesu ever made! Very well built radio, very sensitive and selective receiver, and sounded almost as good as the Kenwood Hybrids. I always got great RX audio reports with just the Yaesu hand mic. I liked the 100Hz audio filter for PSK. The VFO was very stable, and I never had the slighest bit of trouble with the radio. Much better performance than any of the newer Yaesu radios. If you find one of these at a good price, buy it! |
|
| MW0HRD |
Rating:      |
2005-01-05 | |
| good solid radio |
Time Owned: more than 12 months. |
I have now owned my FT902DM for about 16 months and for its age had only the usual problems when i first got the radio relays switches etc nothing much. I have worked the world on it and would not part with it never had a bad report the audio is superb. with 100w out I paid £150 you cannot go wrong. I would recomend this radio to anyone. but do not get one if you dont like to plate & load
73 to you all Chris S-Wales |
|
| PY3KT |
Rating:      |
2004-12-20 | |
| Great radio |
Time Owned: more than 12 months. |
I appreciate so much this type of equipment, therefore as a friend said: "tube radios have soul". Excellent receiver and trustworthy transmitter, with good quality of audio. It is between my preferring, because remembers my old Yaesu FT101-ZD and it adds quality in all the directions.
73 and greetings from Brazil
PY3KT - Joel Costa |
|
| VE8NSD |
Rating:      |
2004-10-15 | |
| I like mine, but... |
Time Owned: more than 12 months. |
I got mine as part of a package deal with the phone patch, ant tuner, VFO, and 'scope.
The Astatic D104 really makes the audio sound good. I received a lot of unsolicited compliments on my TX audio.
I saw an Inrad SSB filter on eBay, bought it, and love it. The transformation is literally like having a different (better) receiver. Really incredible. BUT the drawback is that the receive audio now is "communications" quality instead of "high fidelity". |
|
| G1EUZ |
Rating:      |
2004-08-12 | |
| Keeper |
Time Owned: more than 12 months. |
I have 2 Radios, the ICOM 718 and the FT-902DM.
It took me 12 Months to refurbish the 902DM fully, I bought it with several parts missing, and managed to track them down via the web. Now I cannot leave it alone.
A useful link for the counter board replacement chip is here:
http://homepage3.nifty.com/RadioGaGa/COUNTER_e/
also check out the 901/902dm group on yahoo:
http://groups.yahoo.com/group/FT-901/
The modern Icom rig is great for fast fun, but for that lamplight and heater glow, I keep returning to the 902DM. Alignment can be tricky, but when you get it right - it's great.
Mick |
|
| G3ZPS |
Rating:     |
2002-05-31 | |
| Great value for money |
Time Owned: N.A. |
After a 20 year break from the hobby I started collecting Yaesu FT rigs of this vintage in 2002. Maybe its my age but for me they are easier to repair.
I couldn't turn down my FT902DM, with phone patch speaker and FC902..almost unmarked!!. Output pwer was low on all bands (less than 70Watts) compared to my 101ZD's and this was quickly traced to a defective OP tube, now well over 100W on the lower bands. The Receiver is excellent with a very low noise floor. One of the main differences to the 901 is the diode first mixer (instead of FETs), also many of the Yaesu 901 mods are fitted. The 10 second tune up timer can be annoying for old hands who can tune up tube rigs without it. Memory is basic, but useful for checking back on stations on the band you are on.
The 902DM has AM and FM options fitted, the narrow CW filter was I think an option, but with the Audio Peak Filter its a pretty good CW rig
I'm certain there is no 902DM workshop manual just the 901 manual with an addendum for the 902.
Also very heavy compared to tiny modern rigs. As they say.. its a keeper!!
G3ZPS London UK |
|
| W3HKK |
Rating:      |
2002-05-13 | |
| A classic all-mode rig for great ssb and cw |
Time Owned: more than 12 months. |
I have used an FT-901DM (see my other review) for 23 years and love it. In fact, I still use it as a back up station on a regular basis.
So, two years ago, when I came across a complete, like-new 902 station, for sale at a ham fest, I couldnt resist. I agree with all the other 902 commentaries. Its a quality durable professional grade xcvr with great flexibility and multimode operation. It excels on ssb and cw.
I too stumbled a bit when trying to align it due to errors andomissions in the owners manual. ( what Yaesu did was a poor job of updating the FT-901DM manual to cover WARC band alignment procedures.) But after one stumble, and a day or two to regroup, I added the missing steps, and completed the neutralization/alignment- with terrific results.
MY 902 had been modified for cb use, so watch out for this. But it is a simple matter of ordering replacement xtals ( 4) and tweaking BOTH the XTAL Unit and the VCO unit to restore normal output on 10M.
This remains an exceptional rig andhas held up amazingly well for its age.
de Bob W3HKK |
|