Hi, I've recently purchased what looks like an old Ex WD unit, with no
identity plates, and I'd really like to identify it, I'm sure its a
receiver though it could be a converter of some description, quite
large front panel 280 by 170mm 300mm deep, centre left of the front
panel are three controls marked Aerial RF and Oscillator, each having a
little window that clicks round 0 to 9, to the right is a paxolin
panel with test points marked V1 to V10, bottom of panel sockets left
to right marked RF input, Output, Power Input, Gain control, inside the
three front panel controls connect to what looks like a front end box
which held two valves marked VR138 and VR137, there are then six IF
cans with a single coil inside and six valve holders alongside marked
VR65 , something is missing from the top front of the front panel that
once connected to the "front end" also right hand side of chassis has a
socket marked IF, The "front end coils look about 30-40 mhz (guess) and
the IF coils about 7-10mhz another guess, I can send a pic to anyone
who thinks they know what it once was, thanks for looking, from Ron
g3yuh...

"ron_ayling" wrote:

Hi, I've recently purchased what looks like an old Ex WD unit, with no
identity plates, and I'd really like to identify it, I'm sure its a
receiver though it could be a converter of some description, quite
large front panel 280 by 170mm 300mm deep, centre left of the front
panel are three controls marked Aerial RF and Oscillator, each having a
little window that clicks round 0 to 9, to the right is a paxolin
panel with test points marked V1 to V10, bottom of panel sockets left
to right marked RF input, Output, Power Input, Gain control, inside the
three front panel controls connect to what looks like a front end box
which held two valves marked VR138 and VR137, there are then six IF
cans with a single coil inside and six valve holders alongside marked
VR65...

With those valves, it's ex-RAF, probably late WW2 to 1950s vintage.

VR137 is an EC52 low power VHF transmitting triode on B9G base.
VR138 is unlisted in anything I have to hand, unfortunately.
VR65 is an SP61 pentode (100MHz max frequency) on Maxda Octal base.

The EC52 is capable of 7 watts and 300MHz, so it's a transceiver
or transponder of some sort, I'd guess. (Possibly IFF?)

Hope this is some help,

Chris.

Hi Chris
My mistake the other valve is a VR136 not VR138 the unit is a bit
tarnished, strange that transmitting valve is there? I can't believe
its a transmitter, or transmits in any way, there is no change over and
the controls and connections are real simplicity, it looks like a
straightforward simple HF receiver? Anyway thanks for the info, I guess
by the lack of replies its an unusual one
cheers
from Ron...


Chris Suslowicz wrote:
"ron_ayling" wrote:

Hi, I've recently purchased what looks like an old Ex WD unit, with no
identity plates, and I'd really like to identify it, I'm sure its a
receiver though it could be a converter of some description, quite
large front panel 280 by 170mm 300mm deep, centre left of the front
panel are three controls marked Aerial RF and Oscillator, each having a
little window that clicks round 0 to 9, to the right is a paxolin
panel with test points marked V1 to V10, bottom of panel sockets left
to right marked RF input, Output, Power Input, Gain control, inside the
three front panel controls connect to what looks like a front end box
which held two valves marked VR138 and VR137, there are then six IF
cans with a single coil inside and six valve holders alongside marked
VR65...

With those valves, it's ex-RAF, probably late WW2 to 1950s vintage.

VR137 is an EC52 low power VHF transmitting triode on B9G base.
VR138 is unlisted in anything I have to hand, unfortunately.
VR65 is an SP61 pentode (100MHz max frequency) on Maxda Octal base.

The EC52 is capable of 7 watts and 300MHz, so it's a transceiver
or transponder of some sort, I'd guess. (Possibly IFF?)

Hope this is some help,

Chris.

Might be a radar receiver of some sort with those 6 IF stages. Should be
able to check them out with a grid dip oscillator to see what frequency
they are on. 30MHZ???


My data books shows the VR136 equivalents as a CV1136 or CV380.
Civilian equivalents are the EF54 or RL7 which are a sharp cut off
pentode used as a UHF Amplifier. Base is European 9 pin lock-in type.

73

Lionel
VK4NS


ron_ayling wrote:
Hi Chris
My mistake the other valve is a VR136 not VR138 the unit is a bit
tarnished, strange that transmitting valve is there? I can't believe
its a transmitter, or transmits in any way, there is no change over and
the controls and connections are real simplicity, it looks like a
straightforward simple HF receiver? Anyway thanks for the info, I guess
by the lack of replies its an unusual one
cheers
from Ron...


Chris Suslowicz wrote:

"ron_ayling" wrote:


Hi, I've recently purchased what looks like an old Ex WD unit, with no
identity plates, and I'd really like to identify it, I'm sure its a
receiver though it could be a converter of some description, quite
large front panel 280 by 170mm 300mm deep, centre left of the front
panel are three controls marked Aerial RF and Oscillator, each having a
little window that clicks round 0 to 9, to the right is a paxolin
panel with test points marked V1 to V10, bottom of panel sockets left
to right marked RF input, Output, Power Input, Gain control, inside the
three front panel controls connect to what looks like a front end box
which held two valves marked VR138 and VR137, there are then six IF
cans with a single coil inside and six valve holders alongside marked
VR65...

With those valves, it's ex-RAF, probably late WW2 to 1950s vintage.

VR137 is an EC52 low power VHF transmitting triode on B9G base.
VR138 is unlisted in anything I have to hand, unfortunately.
VR65 is an SP61 pentode (100MHz max frequency) on Maxda Octal base.

The EC52 is capable of 7 watts and 300MHz, so it's a transceiver
or transponder of some sort, I'd guess. (Possibly IFF?)

Hope this is some help,

Chris.

In article . com,
"ron_ayling" wrote:

Hi Chris
My mistake the other valve is a VR136 not VR138 the unit is a bit
tarnished, strange that transmitting valve is there? I can't believe
its a transmitter, or transmits in any way, there is no change over and
the controls and connections are real simplicity, it looks like a
straightforward simple HF receiver? Anyway thanks for the info, I guess
by the lack of replies its an unusual one

VR136 is another B9G base, and is an EF54, again with a maximum operating
frequency of 300MHz.

I'll have to dig out my Yeeha! password and have a look at the photo.

One thought: if it's steel-cased it's probably ground based kit, as most
of the airborne stuff was aluminium to save weight.

Chris.

--
If Usenet did not exist, nobody in their right mind would invent it.

Hi Chris
Thats a good point! its very heavy all steel construction so as you say
probably Land based, I have tried to GDO the front end coils, and get a
good dip on the RF and Osc coils around 38 mhz, The antenna coil I
can't find a dip although the coils look very similar in all three
stages, So what would a fairly high gain fairly fixed freq receiver be
doing on a military airfield during WW2 with a VR138 in it?
By the way I noticed there is also a valve diode base in the front end
similar to an EA50 type I would think and another at the end of the IF
chain
from Ron...




Chris Suslowicz wrote:
In article . com,
"ron_ayling" wrote:

Hi Chris
My mistake the other valve is a VR136 not VR138 the unit is a bit
tarnished, strange that transmitting valve is there? I can't believe
its a transmitter, or transmits in any way, there is no change over and
the controls and connections are real simplicity, it looks like a
straightforward simple HF receiver? Anyway thanks for the info, I guess
by the lack of replies its an unusual one

VR136 is another B9G base, and is an EF54, again with a maximum operating
frequency of 300MHz.

I'll have to dig out my Yeeha! password and have a look at the photo.

One thought: if it's steel-cased it's probably ground based kit, as most
of the airborne stuff was aluminium to save weight.

Chris.

--
If Usenet did not exist, nobody in their right mind would invent it.

In article .com,
"ron_ayling" wrote:

Hi Chris
Thats a good point! its very heavy all steel construction so as you say
probably Land based, I have tried to GDO the front end coils, and get a
good dip on the RF and Osc coils around 38 mhz, The antenna coil I
can't find a dip although the coils look very similar in all three
stages, So what would a fairly high gain fairly fixed freq receiver be
doing on a military airfield during WW2 with a VR138 in it?

Radar receiver? The early stuff worked in the 20 - 50 MHz range, and
they might have used a fairly chunky valve as the RF input stage to
protect things from the substantial transmit pulses. Alternatively
it may just be the LO because it was a convenient triode that would
work at the desired frequencies (and the VR136 is the RF preamp).

By the way I noticed there is also a valve diode base in the front end
similar to an EA50 type I would think and another at the end of the IF
chain


AVC and detector? Dual AVC? If the IF strip is single coil, it's
probably wideband for pulse use... another clue to radar applications!

Best,
Chris.

--
"With its diet of keycaps, mouse-balls and Ethernet terminators, the
Aardvax can be a potentially serious pest in computer installations"
-- Tanuki in a.s.r

In article ,
(Chris Suslowicz) in
rec.radio.amateur.boatanchors writ:


"ron_ayling" wrote:

Hi, I've recently purchased what looks like an old Ex WD unit, with no
identity plates, and I'd really like to identify it, I'm sure its a
receiver though it could be a converter of some description, quite
large front panel 280 by 170mm 300mm deep, centre left of the front
panel are three controls marked Aerial RF and Oscillator, each having a
little window that clicks round 0 to 9, to the right is a paxolin
panel with test points marked V1 to V10, bottom of panel sockets left
to right marked RF input, Output, Power Input, Gain control, inside the
three front panel controls connect to what looks like a front end box
which held two valves marked VR138 and VR137, there are then six IF
cans with a single coil inside and six valve holders alongside marked
VR65...

With those valves, it's ex-RAF, probably late WW2 to 1950s vintage.

VR137 is an EC52 low power VHF transmitting triode on B9G base.
VR138 is unlisted in anything I have to hand, unfortunately.
VR65 is an SP61 pentode (100MHz max frequency) on Maxda Octal base.

The EC52 is capable of 7 watts and 300MHz, so it's a transceiver
or transponder of some sort, I'd guess. (Possibly IFF?)


Dunno, can't remember ever seeing one of those as a power amp.
Usually they were the local oscillator for VHF kit. I don't recognise
the stuff as described, but the Gee nav receiver had a similar valve
line-up if my memory is right. The main chassis was the R1355, with
6? SP61 IF amps, and the RF26/7 plugins were EF54 RF, EF54 Mixer, EC52
LO. Suggest a repackaged Gee rx to the OP. Tuned 20-70 Mc/s, IF
7Mc/s, again trusting my memory.

R1355 wasn't much use for anything, save that the RF26/7 units were
stripped down for the very well made 2 gang and single gang 75pf
tuning caps, and the Muirhead epicyclic drive. Many amateurs bought
one of the RF2?-25 plugins for a lifetime's supply of 30 pf beehive
trimmers, I'll be leaving half a dozen beehives to my heirs.

j.