b95. PYE PMR mods
b95. PYE PMR mods
XTAL
frequency list; see AR november 92, page 6, may translate the
info later
Most PMR rigs are good when you know the problems and takes steps
to avoid the bad things with the rigs. Here is described some
rigs I have
tested over several years as packet radio nodes and beacons on 2m
and 70cm.
PYE modifications
The first PMR rig I had was a PYE reporter,
it was back in 1968, but I never got it into use, had
other ideas and built my own solidstate transmitter instead. Also
had a PYE Vanguard AM25B, and
made many experiments with it so it was discarded, and I bought
an AM25T which was used in my car
until battery was flat because I forgot to switch it off over
night. .
Have attended a course for Storno CQF612 and PYE T30FM, and I
must admit that I've carried out many
experiments with the PYE equipment at work and really was well
reputed for improving these for maritime
mobile VHF operation. PYE has a very bad reputation in Norway,
but it is not so much PYE which is bad
as it is caused by some fools who installed germanium diodes in
the antenna connection, to drive a relay
used for reporting that the transmitter was on the air. It caused
terribly bad intermodulation.
PYE
FM10d/AM10d (Cambridge), AM25B, AM25T (Vanguard), F60FM etc
These are old and based on transistors from early 60's with very
typical construction
philosophy which is often bad today. They may have some
historical collection
value for boatanchor societies.
**
Please note that the mains transformer found in F60FM transmitter
may be used in a 600-1000W PEP
SSB power amplifier, it is as such a highvalue component
overlooked by most of us
** Since the Cambridge has an inverter it could be used as power
supply for other boatanchor rig
PYE W15FM Westminster is an old rig and
possibly not worth using too much time with,
however, it has some valuable parts. The exciter is good, while
the PA is not so good(!).
My last application is the LA3VHF 2m beacon, but used low noise
xtal oscillator and Philips
BGY36 PA module. A similar 2m beacon (LA6VHF) was made on PYE
T30FM chassis, it uses
the original psu, exciter and power amplifiers.
T100FM/T100MN
Have studied the equipment, but have nothing left. The exciter
and audio stages are equal to T30FM
F30FM (T30FM and R18FM/R17FM)
Have done some extensive work with these and modified a lot to be
improved for maritime VHF, bu I am not sure if it is still worth
bringing some info for such equipment. Used one transmitter for a
2m beacon in Kirkenes. It is very much the same as W15FM.
Unfortunately much equipment has been modified by unskilled
persons and the reputation is worse than it deserves.
PYE W15FM.
Had a lot of these rigs for 2m and 4m since the local
police, and electric power board
took at lot of them out of service in late 80's. The
local amateurs only wanted new equipment.
PYE has been famous for the relay on 12VDC line, here is the
modified
version I use on LA3VHF beacon. The floating ground is very bad
for spurious,
an no need if you don't have an English car, but the relay is
still a good idea.
It may be an expense at first, but an advantage in the end.
PYE R18FM
(F30FM).
19in. rack mounted receiver.
Had a lot of these
rigs (with T30FM) to play with since the Norwegian telecomms
changed to
Storno CQM612, first the PMR stations in the 70's and later, the
maritime mobile stations around 1990.
It is a good receiver. But it is important to cover underside of
the RX tuner lid with tape to
avoid it from touching the coils and this upsets the trimming so
you need to align it every time
you've had the lid off. Even if the original receiver has good
sesitivity at 160MHz, it will not
operate properly on 144MHz (ref.: LA5QEA), but I used a BF905 MOSFET as RF amplifier
and it
was no problem to achieve 20dB quieting for 0.25µV pd signal.
BF905's were available at
no cost, but the later BF981 or whatever are supposed to be just
as good.
Also tested an S-meter based on the IF signal in R17 and R18.
PYE R17FM is older version of the 19" rack
mounted receiver, it is in many respects very much
like W15FM Westminster, and it hasn't the meter on the front
panel. It is two versions of PYE Westminster.
1967 version has BJT transistors in the VHF module, while 1968
version has JFETs. Suppose R17FM
has the latter JFETs. We used the IF and AF part of an R17FM for
the local repeater
with valve circuits for VHF part of the old Storno (CQM12?)
receiver, it was a vaste improvement.
7c PYE T30FM power amplifier mods
The first thing to
do is to put solder lugs on as many screws as possible for good
ground connections on the
printed circuit boards. Use of the floating ground will only
cause bad spurious problems. The power
amplifier needs few modification for proper operation. An
unmodified stage
may hardly deliver 12W, but the modified stage easily produces
20-25W RF. And it is just by addition
of some resistors and capacitors for better balance the power to
the two power devices. You may well
try some extra 100pF capacitors from base to
emitter on either power transistor. It is just what we have
experienced later, but the companies counted a pence when you
really don't care for a few extra capacitors
to increase the gain..
Had a lot of these rigs (with T30FM) to play with since the
Norwegian telecomms changed to
Storno CQM612, first the PMR stations in the 70's and later, the
maritime mobile stations around 1990,
also had some T100MN.
T60FM.
Before you put it into the
bin, you should consider that the mains transformer is very
useful for a medium power amplifier,
and may have high value on junksale. If you want to build an
audio amplifier or PA, you must pay a lot of money to get
a similar transformer today. Two transformers in parallel are
good for over a 1kW RF power.
PYE Westminster W15FM
AT10793/5 filter for W15FM (LA5QEA)
AT11437/1 (HC6/U looking can) filter for W15FM
(measured by LA5QEA)
see also application of W15FM
for LA3VHF 2m beacon on page d31
,
and application for R17FM as IF amplifier for repeater on page n31
PYE Europa.
Got over a douzen of
these equipment from a friend where they were discarded at the
job.
Would never have paid for it, but it is a a few things to
salvage. It must be considered how much else it is worth to use
time to remove.
Apart from the box, which is suitable for
many other projects, I see only four components worth salvaging:
The antenna relay on the left side, two compression trimmers
below it, and BLY53 (2N5944) on the rear.
The xtal filter is for 21.4MHz, so it might be needed for your
junkbox.
Here it is used to house a INTERLINK 23cm packet
transceiver,
PYE Europa is supposed to be rather unstable and the
service-man's nightmare.
Since I had some douzens of T30FM and W15FM 2m equipment I see no
reason for wasting my time on this type of equipment.
You'll find the data for MD951 type coax-relays
in SSB Electronics catalogue 1984. I bought such relays
at a rally in UK, and have used one for my remote 2m BFT66
pre-amp since 1980. According to Ian, G3SEK
the power limit (not switching power) is 450W on 2m, so it is
really a useful piece to remove before
you discard the rest! Careful to take care of the old mounting
hardware as it is difficult to connect the coax cables without.
se forøvrig
følgende artikler om PYE utstyr:
PYE REPORTER (4m) ombygging til
2m
LA1ZH AR 69-02-033
PYE Vanguard AM25B og
AM25T
LA8AK AR 92-11-006
PYE Westminster for 50/144/432MHz
bånd
AR 94-03-068
PYE Westminster W15FM
mottakerforbedring
AR 94-01-007
PYE Westminster for 50/144/432MHz
bånd
AR 94-04-100
PYE F30FM 2m 25W sender/mottaker forbedringer LA8AK
AR 90-03-068
PYE utstyr; 12MHz TX
xtals
LA5QEA AR 93-02-036
PYE utstyr brukes til forbedring av rør
repeater AR 92-12-
PYE Westminster deler i 10m
mottaker
AR 93-05-133
PYE Westminster deler i 2m signal
generator
AR 88-04-103
PYE R18FM som repeatermottaker
(2)
AR 93-09-248
PYE R18FM som repeatermottaker
(1)
AR 93-06-174
PYE F60FM, FM10d(Cambridge),
FM25D(Vanguard)
AR 93-06-174
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2004.07.31