Date   

Re: Clip-on Crystal Ovens/Heaters

Russ Stewart <g4pbp@...>
 

Richard wrote:

On Sat, 31 Jul 2010 15:15:49 -0000
"GM8BJF" <brian.flynn@tiscali.co.uk <mailto:brian.flynn%40tiscali.co.uk>> wrote:

I am currently building up a new Tx for the Edinburgh 23cm beacon,
GB3EDN and
am looking for a ssource of clip-on ovens for HC49 crystals. I know that
Kuhne do them but wondered if there is another source of such
devices. It
does not need to be terribly high spec as the crystal is going to be
locked
up to a decent standard. The purpose is just to keep it close to
frequency so
that the RDDS will pull into lock under all ambient conditions.

73s

Brian.

Gm8BJF
Hi
Eisch-Kafta-Electronic do them www.eisch-electronic@t-online.de <mailto:www.eisch-electronic%40t-online.de>
part no Qterm1 @ €5.50 they might be a bit more as my catalog is out of date.

HTH

--
Best wishes

Richard Bown G8JVM

###################################################################################
Registered Linux User 36561
OS: Mandriva 2010.1 Powerpack on an AMD Dual Athlon 64 +4400: 8 GB RAM DDR2
Ham Call: G8JVM , QRA IO82SP, Interests Microwave 1.3 GHz,2.3 GHz & 5.7GHz & 10
GHz
###################################################################################

Got some if you need one Brian they are Murata PTH bg330n .... Russ .... g4pbp


Tonight - Microwave Activity Night, 8/2/2010, 8:00 pm

ukmicrowaves@...
 

Reminder from:   ukmicrowaves Yahoo! Group
 
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Date:   Monday August 2, 2010
Time:   8:00 pm - 9:00 pm
Repeats:   This event repeats every week.
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Re: Off Topic -- Warning re surplus Nokia Tetra base station Power a

F1CHF
 

Mark
I don't remember why, but my Excel page for slot antenna
was updated ...
please find the link
 
regards,
 

----- Original Message -----
Sent: Sunday, August 01, 2010 12:17 PM
Subject: Re: [ukmicrowaves] Re: Off Topic -- Warning re surplus Nokia Tetra base station Power a

 

Roy,
some pictures of these on my website  www.dc2light.co.uk with a few notes on problems found. Russ managed to get round these issues with major surgery, I have yet to modify mine since cooking the op pcb transmission line, but I think that as per Chris DGU's suggestion, a fin on the track will greatly reduce the temperature without too much radiation, even though the board seems to be fibreglass not PTFE. An additional small fan here will also cool the sageline op coupler (which will also get a fin!)
 
still available on eBay i believe
 
 Regards
Mark GM4ISM

Sent: Sunday, August 01, 2010 10:53 AM
Subject: [ukmicrowaves] Re: Off Topic -- Warning re surplus Nokia Tetra base station Power a

 

hi all
sorry to plead ingorance but im new to the goup .
what Tetra Amplifier are we talking about please.
cheers
roy
GM4VKI
 



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Re: Off Topic -- Warning re surplus Nokia Tetra base station Power a

Mark GM4ISM
 

Roy,
some pictures of these on my website  www.dc2light.co.uk with a few notes on problems found. Russ managed to get round these issues with major surgery, I have yet to modify mine since cooking the op pcb transmission line, but I think that as per Chris DGU's suggestion, a fin on the track will greatly reduce the temperature without too much radiation, even though the board seems to be fibreglass not PTFE. An additional small fan here will also cool the sageline op coupler (which will also get a fin!)
 
still available on eBay i believe
 
 Regards
Mark GM4ISM

Sent: Sunday, August 01, 2010 10:53 AM
Subject: [ukmicrowaves] Re: Off Topic -- Warning re surplus Nokia Tetra base station Power a

 

hi all
sorry to plead ingorance but im new to the goup .
what Tetra Amplifier are we talking about please.
cheers
roy
GM4VKI
 



No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.851 / Virus Database: 271.1.1/3042 - Release Date: 07/31/10 19:34:00


Re: Off Topic -- Warning re surplus Nokia Tetra base station Power a

Russ Stewart <g4pbp@...>
 

rkavampsev@aol.com wrote:

hi all
sorry to plead ingorance but im new to the goup .
what Tetra Amplifier are we talking about please.
cheers
roy
GM4VKI

Hi Roy it's a 70cms unit with a pair of BLF548's; or should I say was a 70cms amp.

70cms is a bit 'off topic' for this reflector but really all sorts gets discussed / reported here; anyway welcome

regards des Russ .... g4pbp


Re: Off Topic -- Warning re surplus Nokia Tetra base station Power amps on 70cms

Russ Stewart <g4pbp@...>
 

Russ Stewart wrote:
Christopher Bartram wrote:

Having designed TETRA PAs, I assume that these surplus amplifiers are designed to deliver 50 - 60W pep, and will produce >200W simply because they were run 'backed-off' in order to get good large signal linearity with a relatively poorly-performing lineariser. I should stress that I don't know these amplifiers, but the problems which Mark and Rob describe aren't black magic!

The issues which will arise from running the amplifiers at higher powers will (probably) be due to the choice of substrate for the microstripline output matching elements. If, as I suspect, the amplifiers are built on 0.62 or 0.31mm FR4 to save money, the major issue will be resistive heating due to dielectric losses, not dielectric breakdown. While you can't do a lot about the latter, the heating due to resistive losses in the substrate can be dealt with in the same way as you'd deal with losses in a resistor: heatsinking!
The power dissipated in a microstripline can be calculated, but as a rule of thumb, those in a 200W PA will probably only dissipate a few watts.
The characteristic impedance of a microstripline is relatively uneffected by heatsinking structures placed on top of the conductor. A U-shaped heatsink of, say, 0.25mm copper sheet soldered to the conductor will radiate the heat dissipated.

One tool which anyone designing, building or modifying a solid state power amplifier should possess is an infra-red thermometer. These are cheap and being non-contact, can be used to look at a the temperatures of PA components while it is running. Thermal design is often neglected in amateur designs.

Vy 73

Chris
GW4DGU


------------------------------------

Yahoo! Groups Links




Hi Chris and I guess you are right on all counts.

I am actually using one these amps but envoked radical surgery to stop it burning up. It currently gives 280W o/p cold and drops to 240W when hot. It easily does 250W PEP !

The surgery involved firstly, cutting out the PA section from the main board and remounting it on the original heatsink. I left the bit of board which was the o/p line of the driver stage, (for matching purposes). I connected a piece of UT141-50 to this line and put a 10pf ceramic trimmer across the the coax / stripline transition to the gnd plane; this gave a 1:1 match when the o/p peaked (1st time ever :-)

At the output end I cut off the SWR monitor line part and stripped off the 50ohm track feeding it, right back to the Sageline combiner, just leaving a small pad which the Sageline is connected to. The used a piece of UT141-50 to bring out the RF. Without the line removal I could only get 230W cold.

It was interesting to note that when I stripped off the stripline, the bit of board under where the o/p N-type spigot was soldered, was already black + burned even under the amps normal operating condition !

The o/p Sageline combiner is at or just over it's power limit at 280W and seems to be the primary heat source; you can't hold your finger on it after 5mins of carrier !!! So I blow the combiner and am currently testing use of a 20mm fin (copper strip) soldered to it's length in the air flow. I will know how well this works shortly .... need an IR camera for Christmas for all this PA work Hi. It would be easy to replace the Sageline with an external Wilkinson in UT141-75 as an alternative.

Finally and most importantly, as Mark found in his original mods, you must 'beef-up' the DC feed to each device and not rely on the via's and pc tracks than feed the DC pwr; this will result in a 'burn-up' and general mess.

If anyone needs it, I have photographs of the finished PA, these may already be on Mark's website.

All I need now is someone to work on 70cms :-(


regards de Russ G4PBP



------------------------------------

Yahoo! Groups Links




THE LATEST !!!! ..... it's dead.

The newly modified Tetra 70cm amp passed away peacfully last night whilst testing with DF9IC :-)

It passed my 1hr / 5min thermal cycling test. I did not do my 80% carrier on test for > 1hr test as I reckoned the Tetra would set on fire, as it is being run too far above it's design spec. for comfort. I opened it it up expecting to see 'burned things' but there were none !

Everything looked new and shiney except the device gates had 26V on them :-(

It looks like an overdrive or maybe a sequencing issue, the SWR was fine but I thought I had the sequencing sorted. Mark suggested it could be the common problem with Jap rigs of a high peak switch on RF pulse. I never thought to check this; the IC810H has only ever driven valves histortically. Very remiss really missing such an important test, as I was trying to push the BLF 548's to near their maximum rating.

So a salutary warning again to those trying to push these amps above 200W, yes they will do nearly 300w but for how long I will now never know.

Anyway it died honourably in the persuit of DX so it will recieve a hero's burial later today ..... RIP TETRA


regards de Russ ..... G4PBP


Re: Off Topic -- Warning re surplus Nokia Tetra base station Power a

rkavampsev@...
 

hi all
sorry to plead ingorance but im new to the goup .
what Tetra Amplifier are we talking about please.
cheers
roy
GM4VKI
 


Re: Clip-on Crystal Ovens/Heaters

Richard <richard.bown@...>
 

On Sat, 31 Jul 2010 15:15:49 -0000
"GM8BJF" <brian.flynn@tiscali.co.uk> wrote:

I am currently building up a new Tx for the Edinburgh 23cm beacon, GB3EDN and
am looking for a ssource of clip-on ovens for HC49 crystals. I know that
Kuhne do them but wondered if there is another source of such devices. It
does not need to be terribly high spec as the crystal is going to be locked
up to a decent standard. The purpose is just to keep it close to frequency so
that the RDDS will pull into lock under all ambient conditions.

73s

Brian.

Gm8BJF
Hi
Eisch-Kafta-Electronic do them www.eisch-electronic@t-online.de
part no Qterm1 @ €5.50 they might be a bit more as my catalog is out of date.

HTH

--
Best wishes

Richard Bown G8JVM

###################################################################################
Registered Linux User 36561
OS: Mandriva 2010.1 Powerpack on an AMD Dual Athlon 64 +4400: 8 GB RAM DDR2
Ham Call: G8JVM , QRA IO82SP, Interests Microwave 1.3 GHz,2.3 GHz & 5.7GHz & 10
GHz
###################################################################################


Clip-on Crystal Ovens/Heaters

Brian Flynn GM8BJF
 

I am currently building up a new Tx for the Edinburgh 23cm beacon, GB3EDN and am looking for a ssource of clip-on ovens for HC49 crystals.
I know that Kuhne do them but wondered if there is another source of such devices. It does not need to be terribly high spec as the crystal is going to be locked up to a decent standard. The purpose is just to keep it close to frequency so that the RDDS will pull into lock under all ambient conditions.

73s

Brian.

Gm8BJF


Warning re surplus Nokia Tetra base station Power amps on 70cms

Russ Stewart <g4pbp@...>
 

THE LATEST !!!! ..... it's dead.

The newly modified Tetra 70cm amp passed away peacfully last night whilst testing with DF9IC :-)

It passed my 1hr / 5min thermal cycling test. I did not do my 80% carrier on test for > 1hr test as I reckoned the Tetra would set on fire, as it is being run too far above it's design spec. for comfort. I opened it it up expecting to see 'burned things' but there were none !

Everything looked new and shiney except the device gates had 26V on them :-(

It looks like an overdrive issue (the SWR was fine). Mark suggested it could be the common problem with Jap rigs of a high peak switch on RF pulse. I never thought to check this; the IC810H has only ever driven valves histortically. Very remiss really missing such an important test, as I was trying to push the BLF 548's to near their maximum rating.

So a salutary warning again to those trying to push these amps above 200W, yes they will do nearly 300w but for how long I will now never know.

Anyway it died honourably in the persuit of DX so it will recieve a hero's burial later today ..... RIP TETRA


regards de Russ ..... G4PBP


Webstreaming of Space Colloquium has started

M5AKA
 

See http://www.batc.tv/ - click on Live Events

Enter "/nick callsign" (e.g /nick M0ABC") in the chat window.

Schedule of Presentations
http://www.uk.amsat.org/content/view/713/284/1/2/

AMSAT-UK
http://www.uk.amsat.org/

73 Trevor M5AKA
----


Re: RF2115 FET (not the chip)

Dave
 

Hey Andy,

My initial guess would be that its a MRF2115 Motorola have a habit of dropping
the "M" as often its replaced by other letters eg "SH"RF1234; "X"RF1234
etc etc

cheers
Dave
VK2TDN

At 07:24 PM 30/07/2010, you wrote:
3a. RF2115 FET (not the chip)
Posted by: "Andy Talbot" andy.g4jnt@googlemail.com ac8941
Date: Thu Jul 29, 2010 11:34 am ((PDT))

I've been sorting through junk in the that goes back an awful long way.
Amongst it have found a box of RF power devices labelled RF2115. These are
the traditional ceramic RF power transistor package with a two hole screwed
fland and four tabs.

(To add confusion, there is now an RF2115 chip, a 900MHz 1 W amplifier, but
this same labelled device far precedes that one). I know they came from a
skip at the previous arbeit-haus, around 1990 ish throwouts from a cancelled
project , and likely a low VHF power device. It biasses up as a MOSFET -
which came as rather a surprise as I'd always assumed them to be bipolar
(clearly never bothered to get one out and even try it). power MOSFETs
were reasonably new then.

I have several tens of these things, and would like to know what they're
capable of before trying to sell on / junking / use in some design or
other.

Does anyone have any idea what they may be. The ceramic package is 9mm
diameter, gold plated flages with opposing sources, labelled on the top in
four lines:
PHI
RF2115
26014
D
Any Inet searching just keeps throwing up the modern chip with this part No.

Also with them were several hundred tiny two-hole balun cores all wound as
1:1 transformers - not even TLTs and wire that wasn't self fluxing - very
odd. But, unfortunately, they seem to be V/UHF types with a low Ur value.
Four turns only measured as 100nH. Since the cores have the same heritage
as the FETs, they presumably are happy at low VHF - if that's what it was.

Andy
www.g4jnt.com


Re: RF2115 FET (not the chip)

geoffrey pike
 

I would guess the "D" is the Vgs threshold value, are they all the same in that respect,
Geoff


--- On Thu, 29/7/10, Andy Talbot wrote:

From: Andy Talbot
Subject: [ukmicrowaves] RF2115 FET (not the chip)
To: ukmicrowaves@...
Date: Thursday, 29 July, 2010, 19:33

 

I've been sorting through junk in the that goes back an awful long way.   Amongst it have found a box of RF power devices labelled RF2115.  These are the traditional ceramic RF power transistor package with a two hole screwed fland and four tabs.   
 
(To add confusion, there is now an RF2115 chip, a 900MHz 1 W amplifier,  but this same labelled device far precedes that one).   I know they came from a skip at the previous arbeit-haus, around 1990 ish throwouts from a cancelled project , and  likely a low VHF power device.  It biasses up as a MOSFET - which came as rather a surprise as I'd always assumed them to be bipolar (clearly never bothered to get one out and even try it).   power MOSFETs were reasonably new then.
 
I have several tens of these things, and would like to know what they're capable of before trying to sell on / junking / use in some design or other. 
 
Does anyone have any idea what they may be.   The ceramic package is 9mm diameter, gold plated flages with opposing sources, labelled on the top in four lines:
   PHI
 RF2115 
  26014
     D
Any Inet searching just keeps throwing up the modern chip with this part No.
 
Also with them were several hundred tiny two-hole balun cores all wound as 1:1 transformers - not even TLTs and wire that wasn't self fluxing - very odd.   But, unfortunately, they seem to be V/UHF types with a low Ur value.  Four turns only measured as 100nH.  Since the cores have the same heritage as the FETs, they presumably are happy at low VHF - if that's what it was.


Re: Contest comms

Barry Chambers
 

Andy

Many thanks for your thoughts. Having just read the WSPR help files, it seems
that WSPR can send 6 digit Maidenhead locators but the message then has to be
sent in two halves. Point taken about a dedicated 200Hz of bandwidth on 2m but
I guess that could be arranged by common consent. OK about the restricted range
of "pseudo" Tx power codes which are available. These would probably be
sufficient for normal use.
I guess the answer is to try it and see what happens. Watch this space!

73

Barry, G8AGN
--


Quoting Andy Talbot <andy.g4jnt@googlemail.com>:

Hi Barry -

Yes, I think the idea could be made to work easily enough. It would be
necessary to use a dedicated 200Hz wide band segment, as the non-standard
messages shouldn't be allowed to get onto the main WSPR reporting network.

Stability could be a problem on 144MHz. It can't really cope with more than
3 -4 Hz of drift over the Tx period, and with a PA coming on for that time,
many HF stations are seen to drift, let alone VHF ones.

Using the power for beam direction is a valid idea, but only a range of
power settings are acceptable to the WSPR decoder. Those are multiples of
1,2 and 5, or 0, 3 and 7dB, so there aren't as many power bits available as
you might think. I believe 'illegal' power values in the source-coded
message were reserved for other functions, but at the moment the rx just
flags up an error if they appear (I've tried it when coding the bits from
first principles - the WSPR software won't allow illegal values, it rounds
the power setting.)

Also the locator is only 4 digits, but I suspect that is not important as
most ops will go and use a database lookup

Andy
www.g4jnt.com


On 29 July 2010 10:48, Barry Chambers <B.Chambers@sheffield.ac.uk> wrote:

Hi Andy

Having read your Data column this month and after my experiences in the
10GHz
contest on Sunday, I'm writing to seek your advice.

On Sunday, I operated portable on 10 GHz and worked 6 stations just by
calling
CQ directly on 10 GHz. The rig was running about 4-5 watts to a 20dB horn.

I can't run high power on 2m and don't like the bother of erecting a beam.
Also,
although I have tried KST, this means getting into the WWW.

I wondered whether it might be feasible to use, say, WSPR on either 2m or
4m
since then I only need low power and maybe only a whip antenna on the car?
I understand from your description of WSPR that one has about 50bits to
play
with - can one fool the WSPR software and put other number/letter
combinations
in the GUI text boxes which will be properly decoded at the Rx? Even as
the
software stands, one could transmit callsign and locator to show that one
was
operational from a /P site. The tx power level box might carry instead a 2
digit numerical code to indicate a particular facet of activity, e.g.
01=beaming north, 02=south, 50=receiving you, etc.

Tests would have to determine the necessary 2m Tx power but hopefully a
handheld
might suffice if it can stand being on transmit for a minute or so at a
time.

Any thoughts?

73

Barry, G8AGN




Re: RF2115 FET (not the chip)

Richard <richard.bown@...>
 

On Thu, 29 Jul 2010 19:33:08 +0100
Andy Talbot <andy.g4jnt@googlemail.com> wrote:

I've been sorting through junk in the that goes back an awful long way.
Amongst it have found a box of RF power devices labelled RF2115. These are
the traditional ceramic RF power transistor package with a two hole screwed
fland and four tabs.

(To add confusion, there is now an RF2115 chip, a 900MHz 1 W amplifier, but
this same labelled device far precedes that one). I know they came from a
skip at the previous arbeit-haus, around 1990 ish throwouts from a cancelled
project , and likely a low VHF power device. It biasses up as a MOSFET -
which came as rather a surprise as I'd always assumed them to be bipolar
(clearly never bothered to get one out and even try it). power MOSFETs
were reasonably new then.

I have several tens of these things, and would like to know what they're
capable of before trying to sell on / junking / use in some design or
other.

Does anyone have any idea what they may be. The ceramic package is 9mm
diameter, gold plated flages with opposing sources, labelled on the top in
four lines:
PHI
RF2115
26014
D
Any Inet searching just keeps throwing up the modern chip with this part No.

Also with them were several hundred tiny two-hole balun cores all wound as
1:1 transformers - not even TLTs and wire that wasn't self fluxing - very
odd. But, unfortunately, they seem to be V/UHF types with a low Ur value.
Four turns only measured as 100nH. Since the cores have the same heritage
as the FETs, they presumably are happy at low VHF - if that's what it was.

Andy
www.g4jnt.com
About 7 years ago I was playing with a PA using 6 4cx250 Bs, I used some FETs
in the driver, they were coming out of a UK company, they had RF prefixes.
At the moment I can't remember who it was, but I'll keep trying.
That company was doing work on Band 2, possible Philips was custom marking
those devices as well. Sorry can't any more help at the moment , but it might
jog someone elses memory.



--
Best wishes

Richard Bown G8JVM

###################################################################################
Registered Linux User 36561
OS: Mandriva 2010.1 Powerpack on an AMD Dual Athlon 64 +4400: 8 GB RAM DDR2
Ham Call: G8JVM , QRA IO82SP, Interests Microwave 1.3 GHz,2.3 GHz & 5.7GHz & 10
GHz
###################################################################################


RF2115 FET (not the chip)

Andy Talbot <andy.g4jnt@...>
 

I've been sorting through junk in the that goes back an awful long way.   Amongst it have found a box of RF power devices labelled RF2115.  These are the traditional ceramic RF power transistor package with a two hole screwed fland and four tabs.   
 
(To add confusion, there is now an RF2115 chip, a 900MHz 1 W amplifier,  but this same labelled device far precedes that one).   I know they came from a skip at the previous arbeit-haus, around 1990 ish throwouts from a cancelled project , and  likely a low VHF power device.  It biasses up as a MOSFET - which came as rather a surprise as I'd always assumed them to be bipolar (clearly never bothered to get one out and even try it).   power MOSFETs were reasonably new then.
 
I have several tens of these things, and would like to know what they're capable of before trying to sell on / junking / use in some design or other. 
 
Does anyone have any idea what they may be.   The ceramic package is 9mm diameter, gold plated flages with opposing sources, labelled on the top in four lines:
   PHI
 RF2115 
  26014
     D
Any Inet searching just keeps throwing up the modern chip with this part No.
 
Also with them were several hundred tiny two-hole balun cores all wound as 1:1 transformers - not even TLTs and wire that wasn't self fluxing - very odd.   But, unfortunately, they seem to be V/UHF types with a low Ur value.  Four turns only measured as 100nH.  Since the cores have the same heritage as the FETs, they presumably are happy at low VHF - if that's what it was.


Re: Binocular cores

Andy Talbot <andy.g4jnt@...>
 

If you can wind your transformers as transmisison line transformers, the ferrite is  unimportant so long as it has enough mu to choke off the common mode currents.  In the VHF region I've experimened quite successfully with air cored tansmission line transformers made from twisted wire.   A good read on the subject can be found here http://www.home.earthlink.net/~christrask/TraskTLTTutorial.pdf
 
Also, just finished a high power MFR151 SSPA using just air wound transformers made from 50 ohms semi-rigid (yes, I know the rules say I should be using 25 ohm coax or lower, but didn't have any of that and 50 ohms works well enough.   44V supply, 280 Watts out, all running cool  says its working)
 

On 29 July 2010 17:19, Joe McElvenney <ximac@...> wrote:
 

David,

Thanks for the gen on EPCOS. I didn't think that ferrites were much use
at VHF as they are often used in suppressors up there. I'm glad that I'm
wrong though as their higher 'mu' means less turns than with powdered
iron.

I do deal with RS Components, and need some other stuff, so will be
placing an order tomorrow.

Thanks 10^6 once again - Joe G3LLV



Re: Binocular cores

Joe McElvenney <ximac@...>
 

David,

Thanks for the gen on EPCOS. I didn't think that ferrites were much use
at VHF as they are often used in suppressors up there. I'm glad that I'm
wrong though as their higher 'mu' means less turns than with powdered
iron.

I do deal with RS Components, and need some other stuff, so will be
placing an order tomorrow.


Thanks 10^6 once again - Joe G3LLV


Powdered Iron Binoculars ?

Joe McElvenney <ximac@...>
 

Hi,

Anyone know of a UK supplier of small, powdered iron, 17-mix, binocular
cores. The trouble with MMICs is they are all power gain and I'm in need
of some volts along with an impedance step-up in the 100MHz region.

Possibly something as used in TV antenna baluns might do the trick but I
prefer to buy new and not pull things apart to get some.


Cheers - Joe G3LLV


Re: Binocular cores

g0mrf@...
 

Hi,

Anyone know of a UK supplier of small, powdered iron, 17-mix, binocular
cores. The trouble with MMICs is they are all power gain and I'm in need
of some volts along with an impedance step-up in the 100MHz region.

Possibly something as used in TV antenna baluns might do the trick but I
prefer to buy new and not pull things apart to get some.

Cheers - Joe G3LLV

Ooops. Sent half way through.
 
There are some suitable ferrite cores made by EPCOS and sold by RS Components.
 
The K1 material is good to 250MHz. I've used them at 145MHz without problem.
 
rswww.com   search for dual aperture cores or EPCOS
 
David G0MRF