FT-847 Most reliable transceiver

k3roj

k3roj

Star Member
If you ever find a Yaesu FT847 transceiver, don't hesitate to buy it since there is no doubt it is one of the best. Having a 100 watt HF transceiver is nice but also having the 144 and 432 bands is even better with this radio. My FT847 is used daily working the local 2 metre repeater and on 2 metre SSB at 144.200 MHz. This radio is very easy for remote control operations using Ham Radio Deluxe and an AZ/EL rotator is easily controlled using third party software. One feature it has that many other transceivers do not is Alphanumeric tagging on each satellite memory which makes it easy to find your favorite sat. Here are many reviews concerning this radio: E-HAM Reviews. My particular FT847 has been in use for 10 years, never runs hot, stays on frequency and is user friendly.
 
I have a FT-847...I have owned it for around 5 years...it is one of many multi band radio's I own all of which are Yaesu...it is without doubt the best...but the 5 years haven't been trouble free...

I bought the radio s/h...it was boxed and in mint condition...it was bought specifically for use on 4m - 2m - 70cm...

I was at the time of purchase using a Yaesu FT-736 for 2m & 70cm but that setup was taking up a whole shelf and I thought it was time to down size (where the FT-736 was once sat sits a VL-1000 and the FT-847)...

First and most noticeable problem was the frequency drift (especially on VHF/UHF)...as soon as you tx on comes the fan directly onto the crystal...this was rectified with the installation of a crystal heater mod supplied by Kuhne Electonic and fitted by our very own G0KZZ some time ago...the whole thing was then covered with a foam sheath to further help stability...the crystal now has a constant temp. of 40 degrees and doesn't go for walkies...one obvious drawback is the fan is constantly on full speed!!..I can live with that...

The next problem isn't (as far as I am aware) a specific FT-847 problem...no power out on 70cm...this was an intermittent problem...as in: when Mark took the radio away to repair the fault there wasn't a fault!!..when it came back there wasn't a fault!!..the fault was eventually traced to bad earth points (3 dry solder joints) on the 70cm pa...

Since both of these repairs (one mod...one repair) have been done the FT-847 has been the backbone of my UHF/VHF operation...trouble free!

I have never used my FT-847 on the Satellite frequencies but I understand that SSB signals don't have to be that accurate so the instability of the crystal isn't a real problem if you are using the rig for it's main function!!..which I'm not!

73 - Tony - G6YWL
 
Yes, you are correct Tony, there is some drifting, especially this time of year here on the east coast in the USA since I only heat my shack just before I use it. I turned my FT847 on and tuned it to a beacon about 40 miles away on 144.283 Mhz. Sure enough, the radio drifted slightly as the room and the radio warmed up. The drifting was never noticed in the past since I never worked any digital modes except for Meteor scatter a few times. I completed the modification yesterday as you described, not using the KUHNE kit but a thermister used by Downeast Microwave which now keeps the crystal around 40 Deg C and sure enough this morning checked it out again and all is well. One other small mod I made when getting the rig was keeping the audio from blaring out with just a slight adjustmant on the volume conrol. According to directions on the internet, I inserted a resistor in series with one of the volume control terminals.
 
My FT847 has been very reliable & I have never needed to take the covers off. However, it was about 2 years old when I obtained it from a deceased estate and apparantly the POWER switch had been replaced in the first two years.

I like the idea of the crystal heater & will do that when I get some time. One question that I had regarding the black foam used to thermally insulate the crystal, it looks like anti-static foam which is quite conductive and could potentially give trouble if it shorts tracks or pads especially when it slowly dis-integrates over time (as some of the black anti-static foam seems to do with time) causing black grit to float around the rig which could be quite nasty. So I would recommend some white styrene foam held on with some heat shrink instead.
73 Lee
 
Hiya Lee.

No, the foam used isn't anti-static foam. What was used is black lagging foam, the kind of thing you buy to keep water pipes from icing up during the winter months, and unlike anti-static foam it is quite flexible with a 'rubbery' feel to it. I know this because I did the mod's on Chaney's FT-847. The foam is most definitely not conductive. :cool:

The crystal heater came from Kuhne Electronics in Germany.

What I have found while working on a number of Yaesu FT-847 transceivers is that you can actually stabilise the temperature quite well by just adding the foam jacket. The big problem (as Chaney mentioned), is that as soon as you go to transmit the cooling fan in the radio speeds up forcing more cold air over the main reference crystal. Once you go back to receive the fan slows down and the crystal starts to heat up again.

What this translates to is a 500-700Hz shift in frequency when checked at 433MHz.

If you only ever operate on HF you may well never notice this drifting at all. Also, if you only use FM on the 2m and 70cm Amateur bands you again may never notice this problem.

Very often I have been asked why Yaesu never made a better job of stabilising the reference crystal, and my guess would be that because the FT-847 was intended for satellite working, it is the 'norm' to experience Doppler shifts of up to around 30-50KHz on the down-links, so a few hundreds hertz extra wouldn't really be noticed! :)

That's my theory anyhow...

73, Mark.
 
Hi Mark,
OK on the foam, yes I know the material you refer to and I am sure it is fine. As you mentioned, the drift is not a problem on FM, but it is readily observed on SSB on UHF. Some of the manufacturers know only too well that the stability of the ref osc is not to good, that is why they produce hi stability reference oscillators as options. It is the hamburger theory "Would you like fries with that" or "Would you like to up-size"
73
Lee
 
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