|TROUBLE SHOOTING TO THE COMPONENT LEVEL..SOME IDEAS AND TIPS. You can do quite a few things with some simple
pieces of test equipment such as a homebrew probe and V.O.M.
|First of all ..you do a DC electrical analysis/set of measurements. ON the PERIPHERY of the schematic you will see numbered bubbles then lines going
to various components. <the numbers on the bubbles correspond to the number stamped on the circuit card holder socket which are all accessible at
the bottom of the radio. Pin 4 would likely be a miniature coax carrying the received signal. D109, a 5 volt zener seems to be there to protect the
circuit from spikes in voltage possibly from static. Sometimes this zener goes bad and even generates alot of noise. Often..there will be
capacitors..which block DC and pass RF..sometimes small signal diodes which act as switches. There are control voltages as follows: constant 12 volts
(12 volts on the circuit at all times), 12 volts present on receive..turns on circuits..through diode switch on receive (RX12) or (R12) ..12 volts on
transmit only. turns on diode switch to provide signal path on transmit. The relay switches these voltages. The relay will switch the radio from
TRANSMIT to RECEIVE and visa versa.
So ..when trouble shooting..number one step is to make sure the DC voltages are present on the circuitry both on transmit and receive. With the
FT301 and its plug in circuit cards...(for example) at the top of the schematic ( o 7 ) is probably active +12 volts on receive to turn on little switching
diode D105 providing a path for rf (amplified rf) to go to the gate of Q103 the mixer.
Using the manual and a bit of detective work will often result in the circuit not only being repaired..(hopefully) but you will also learn how it works or is
supposed to work. An extender card is a nice thing to have. I dont have one built up yet. I often just plug and play. I swap boards with my working
FT301 to find a bad circuit board. I will then start measuring the junctions of diodes for faults but often I can analsyse it down and I have had luck so far
with repairs..usually I have found the fault rather quickly.
|The shop manual or complete SERVICE MANUAL will have test points for DC analysis and then AC analysis. I don't have the SERVICE MANUAL for the FT301. People
I have spoke to ..seem to be having problems getting one. I just use this shop manual. It has enough information for me to find problems. I do have quite a few
spare parts and boards for these ft301s and the odd time people write me for parts. I sell at a most reasonable price. Helps pay for the 2 web sites I have on the go.
NOT really a money maker..more of a retirement activity (like having a job!! only without the pay cheque!!) Helps keep the mind sharp and I (fortunately) have my
civil service pension which keeps the wolf away from the door!!!
|this site was started march 2011 and is still under construction.
I am re writing the articles from my old site
www.earlandrews.com (which is still available)
click here for home page www.hamelectronicsmagazine.com
|The old site
still has lots of the old articles on ham
radio, fishing, elliot lake, ft301, my
parts I sell, the junk rigs I sell parts
from ect..to go to earlandrews dot com
(my old site still active for a few more
CLICK HERE TO GO
|PROBING FOR PROBLEMS
|Simple probing with a homemade signal probe can sometimes find
the fault. Here in the picture is a PROBE that connects to my ham
radio antenna outside. I use a capacitor to couple the probe to the
By probing the radio circuitry with the antenna that is picking up
noise and plenty of signals I can bypass the relays and other
switching and other circuitry to put signals directly into filter circuits
or inputs to rf amplifiers ect. Here..in the picture..the probe on one
side of the trimmer resulted in signals being heard whereas the
other side of the trimmer capacitors was probed and no signals
were being heard.
The signal was not passing through the capacitor. This was
troubleshooting my 40 meter lack of receive problem. There is also
a small brown disc capacitor in parallel with the trimmer. I checked it
and it was ok. The trimmer was replaced with a makeshift capacitor
as per the pictures and it worked. The radio now worked again on 40
meters. I took the trimmer and the fixed value cap out and checked
their operation. They were ok. The problem was poor or bad or cold
With the FT301: bad solder joints are a number one cause of
problems. Crystals going bad or the trimmer needs to be adjusted is
another problem I find.
Another common problem is the RF Unit. Dual Gate Mosfets get
damaged..perhaps by static on the antenna and the zener D109.
The 3sk40 can be replaced by 3n201 or other types of dual gate
mosfets. I have used some cheap in house numbered similar to
MPF121s and they worked fine for me. The leads had to be bent and
formed to fit in the socket or the holes in the circuit board..but they
worked electrically. NTE semiconductor cross reference on the web
can be used to find replacement mosfets. I googled around and
found BF981 can be used..different package device though, NTE454
used according to Fox TAngo web site. Scotts Radio, Dans Small
Parts or even myself..can sell you suitable dg mosfets for the job.
I have to mark the price up a wee bit (20 pct over scotts or Dans but
I sell one device at a time and I send it in an envelope for real
inexpensive postage charge. These devices are static senstive but
are gate protected. I use ESD packing and storage and send it ESD
I sell some parts here and there to help defray the costs of the web
sites I operate. You can write me email@example.com for mosfet prices or
if you need a transistor...two or three or something like that. My
junk- box is a large set of shelves with parts in it.
|Here is one of my homemade probes. A 10 kilohm resistor is used in series in order to
drop down the signal strength of the signal source it connects to. The 10 kilohm resistor
can be by passed as necessary to increase the signal source. Here I have a .005 uf
capacitor I clipped across it. In this case..I could connect the aligator clip to my antenna
and probe around a receiver injecting signals from the outside world.
Another signal source might be my MFJ Antenna analyser. The strength of signal from the
analsyer can be dropped by the resistor or an attenuator. Shown is a homebrew 19 db
attenuator I use from time to time.
A good starting point for receivers is to generate a signal around the IF frequency..9 mhz
for the FT301 and see if the receiver is receiving on the IF frequency. If it receives on
the IF frequency and not on the fundamental frequency then chances are some low level
stage of amplification or mixing is at fault.
|Here for illustration purposes I probe an HW7 radio trimmer capacitor. THESE OLDER SOLID STATE RADIOS from the late 60s, 70s and 80s are fairly easy to work on.
Many of the parts are quite generic. You can substitute parts and they will often work as well or better than the original. I use NTE semiconductor cross reference
and a site www.datasheetarchive.com for data frequently. I can download PDF data sheets, cross references. For technical data ..I join the YAHOO Group for the
radio. There are 2 yahoo groups for the FT301 and almost every radio now has a group. Join the group and you can access the files section to get manuals and
you can get information on parts and part substitutions and some people sell parts or give you info on where to get parts. Sometimes OBSOLETE PARTS can be
very expensive. Sometimes though..you can go out and buy them. Go for a quote and sometimes you will be surprised. These long gone parts are sometimes
available and not that expensive if you shop around. I bought 10 of the TA7089 voltage regulator ICs from Singapore. They cost about $6 with shipping. I could not
get them on ebay or any other on line store but I tried googling and found a search site and got some quotes that were reasonable.
|Below: a very simple
sniffing probe. Can be
used like an antenna as
well to poke around tuned
circuits, capacitors ect to
inject a signal or act like an
external antenna to the
circuit. Below: I check a
capacitor on the Autek RF1
analyst. The capacitors I
checked were OK. Solder
joints were bad.
|As a temporary fix and try out..I used this polyvaricon capacitor in place of the trimmer
and fixed value capacitor in the front end tuned circuit. It worked. The rig now worked
on 40 meters.
|Subject: Re: FT 301
Ok Barry...I dont charge alot for my work..because the rigs are older and it wouldnt make any sense..so
I charge only $10 per hour on the bench. Often..I can offer enough free information through some
emails and the odd phone call
and the problem(s) can be fixed up with no charge at all.
How long have you owned the rig? Is this low power output a gradual thing that happened or a sudden
Can you work on the rig yourself ie..do you have a work bench and maybe a few tools and test
One thing I would try straight off is remove the back end heatsink and label the two coax connectors
top and bottom.
and then jumper the two bnc connectors jwith a jumper wire or perhaps a jumper cable. Then with the
back end off the rig..you will have a 10 watt radio as a result.
NOw you can test to see if the radio puts out the necessary 10 watt drive. If so..then you know the
problem lies in the power output stage you removed.
---> Just off the top of my head..I would say...the problem may be the adjustments in the drive section
under the chasis. There are a set of potentiometers for each band and they control drive. ..but ..this is
a guess Im making.
To ship the entire radio across the border USA and Canada is somewhat difficult now. The border
people dont or wont try and understand the radio is being sent back and forth for repair. ON our side
of the border for imports the border customs people charge a 13 percent HARMONIZED SALES TAX
(HST) much hated over here! Plus they charge a $5 administration fee.
Circuit boards that have no real value or can be sent across the border and claimed as very low
cost..ie $10 are generally left alone. I can send small packages and parts back and forth no probs but
the big stuff is different.
So thats the story. Im retired from federal govt job and I took early retirement option and do this web
stuff and ham radio repair and parts as a sidelne to keep busy..and my mind occupied. ect..ect. My new
web site is www dot hamelectronicsmagazine dot com and it has some good FT301 information on it
(highly recommended) ie where to get the shop manual ect.
So..in summary..I often just help advise people on repairs and I offer parts and I can fix circuit boards
--->>> I should mention..I would recommend you make sure the power supply is working proper. If a
regulator or pass transistor problem..you might be losing voltage when drawing full power and your
rig will not put out full power.
HOpe this helps get you strarted..let me know what you think. 73 earl ve3ab
|I recently gave some email help for a fellow who was just getting back into ham radio. He had purchased 2 FT301s and they needed
some basic work. This is typical of these older rigs. Sometimes they have been "adjusted" by previous owners or maybe even people
using them for 27 mhz operation. I don't charge for these advice sessions by email. I'm always interested in hearing about
troubleshooting these older solid state rigs. I thought I'd share this situation as a story (below).
|Subject: FT 301
Saw your website…well done.
Have a 301 and the power output is only about 25 watts into the FC 301 antenna tuner.
What would you charge to fix my problem? (note: I do email consulatations like this for $0.00 (nil)..I do
enjoy hearing from other FT301 users and old rig enthusiasts and I enjoy the mental challenges of
trying to narrow down the problems with schematics and clues. Something like detective work! -- I
am now writing this on line magazine..using these cases which I am sure ..is interesting to other
hams who are (at times) troubleshooting rigs and electronics gear).
Barry (from W5 land USA)
|Ok Barry. Yes Im always interested in the FT301s. To me it sounds like ..a power source problem...Im
(I advised at this point to double check the power connector on my next page in this series to make sure
the radio had all the proper power connected up to it)
There is a picture of the power cable that runs from the power supply or battery that I use. Maybe..the
wiring is missing a jumper or something and only partial power is getting to your radios or there is a large
voltage drop somewhere.
Could be that the potentiometers (the bank of them) on the underside of the rig..were all adjusted down to
lower the power for each band. Possible I suppose. Or as you say..perhaps a problem with the final
Anyways..good luck. I sell parts here for FT301s but I dont have the final output transistors..in fact..I could
use a few myself. 73 earl ve3ab
I did as your suggested. I placed all the pots into the max
gain position and I get the following:
Thanks for your help.
I am not totally there but it is a start.
I did as you suggested and jumpered the output to bypass the final amp. The most I can
generate is about: 2 watts on 80 meters, 3 watts on 40 meters, 4 watts on 20 meters, 3 watts
on 15 meters.
|The FT301 will put out a bit more than 100 watts. The bank of pots can be adjusted to
maximum position..but ..I would back them off a certain amount.
The 10 meter reading is way off. But he is definitely "getting there".
I suggested to Barry that he purchase a good quality contact cleaner spray such as
CAIG or some other high end brand and "carefully" spray and wipe (with q tips and a bit
of spray) the switch contacts for the band switch and some of the other open contact
switches in the radio.
When using these contact cleaning sprays..read the instructions and use some paper
towel folded pieces to catch the overspray. You might want to read up on using these
sprays on some of the better ham radio and vintage radio restoration web sites and
forums that are on the web. Just google some of them.
The problem with contact cleaner sprays is that they can deteriorate and soften some
plastics and other non metal materials ..so use with prudence.
|This radio had low power output
on all bands.
Maybe the previous owner had
adjusted the rig for qrp use..who
knows.. SOMETIMES..it is the
dreaded 'golden screwdriver'!!!
Someone who is tinkering without
thinking things through!!
Ayways..this is a typical
troubleshooting situation you
might find you have to engage in
when buying a used radio.
Sometimes ..people actually give
me radios. It has happened
several times now! and I buy all
sorts of basket cases as well.
The FT301 has plug in circuit
boards and uses all older discrete
components that are still widely
I sell and have used and new parts
for these radios and if you need a
part or two..you can write me at my
and I'd be pleased to help.
I can do mail order repairs on the
I (unfortunately) do not have any
spare FINAL OUTPUT TRANSISTORS
nor do I have any spare crystals
left. My 10A crystal quit on me just
recently and I had no spares left in
the cupboard! I had sold them all at
the low price of $5 each. NOW ..I
had to go buy a new one from BRY
Brian Carling for about $12. It
worked fine even though it was a
smaller type of crystal with wire
leads. I have adapter pins for
adapting these crystals with wire
leads. One of my other web pages
has the pictures.
I am pretty well sold out of crystals.
I bought some crystals from LES
AF4K and they worked in the FT301
so he may be a source of supply.
|MY NEXT PAGE IN THIS ARTICLE HAS MORE
PICTURES AND TROUBLE SHOOTING IDEAS
for the FT301 (AND OTHER RIGS TOO!!)
These ideas can be used in working on other
rigs or gear.
CLICK HERE TO VISIT THIS PAGE
|This is the back end of the FT301. IF you bridge the
two BNC connectors with a jumper coax or..if you
dont have a cable ..just jumper wire the center pins
together..AND DON'T FORGET YOU HARD WIRED
THEM TOGETHER..you can use the FT301D without
the 100 watt final amplifier section. The 100 watt low
pass filter unit..also pictured on this page..will be in
use with the driver section. In fact Yaesu did make a
10 watt version of the FT301. YOu can then test the
radio for the (approximate) 10 watt drive level.
Barry did this and he got low drive power from 2
watts to 4 watts..which is not enough to drive the
final amplifier stage.
After adjusting the drive level pot bank.(also pictured
on this page) he was able to get almost full power on
Could be..dirty contacts in bandswitch, or bad/lazy
crystal or perhaps crystal trimmer needs a tweaking..
NOTE: when tweaking trimmers..make a pencil mark at
your starting point..so you can always return to the
orignal spot that was working (just ok) previously.
One thing about trimmers I heard..mark starting point
pencil mark..tune trimmer to just when signal
disappears in one direction..then turn opposite
direction to when signal disappears..then put
another pencil mark..THEN adjust the trimmer
capacitor right in the middle of these two points and
you will be fairly close.
This was a trick when adjusting rock bound 2 meter
fm rigs for repeater use in the late 60s.
IMPORTANT POINT..dont be afraid to put marks and
dont stray too far away from adjustment points. and
take photos and draw sketches in a lab book.ect..
|I was doing some reading today of my email files and I came across a case where the
trouble with a circuit was a result of a conductive trace caused when cleaner spray
had been used to clean some contacts.
Conductive traces can be very bad news. I would read the label of the contact cleaner
and I would go to the web site to read about how to properly use these contact
cleaner sprays. I have read nothing but good about CAIG deoxit. It is not cheap to buy.
I think..in industry..equipment is often put into a chamber and ultrasonic energy is
used to remove oxides and unwanted residues. I do not have these facilities though,
a small ultrasonic cleaning machine for small components may be within the reach of
the average technical person at a reasonable cost. It is something I will be looking