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QRP-Labs trimmer caps

 

I am interested in the caps used here.



They look like they may have some good characteristics.
Does any one have a lead on them and a source here in
the USofA?

Inquiring minds want to know.

chuck, k7qo
 

This may not match exactly, but the lettering on top is the same



Michael Medley
AA1MM
 

These are probably Vishay BC caps. They are a copy
of some Sprague-Goodman caps, which are no longer
generally available, of course.

Both Mouser and Digi-Key supply them in the USA.

They are not cheap -- in the USA, Europe, or India.

Jameco has some ceramic caps for about $US1.50
which look pretty good, on the surface of things, anyway.

Hans must have found a lot of them at a good price! Hi.
(But I don't know if Hans uses Vishay caps).

Dan has a few Sprague caps available, but who knows
how many...

john
AD5YE
 

Well, the photo has the letters CYMI molded into the top of the caps.
Googling CYMI results in:



--- Graham

==

On Tue, Nov 28, 2017 at 6:47 PM, chuck adams <chuck.adams.k7qo@...>
wrote:

I am interested in the caps used here.



They look like they may have some good characteristics.
Does any one have a lead on them and a source here in
the USofA?

Inquiring minds want to know.

chuck, k7qo
 

In looking at a blown-up picture from Hans' site, I notice the trim caps
are marked "GVM". There is a GVM Electronics company in Hyderabad, India
but I don't know if they are the makers...

john
AD5YE
 

I think Graham is right. They appear to be CYMI caps in looking
at the picture again. I think he nailed it.

john
AD5YE
 

Chuck,

Like others have indicated. Sprague/Goodman or Vishay. I bought a bunch at Mouser a few years ago. Pricey. The film insulators melt when soldering. Be quick when you solder the tabs. They work well. I used them in band pass filters.

Bill N7EU
 

Hi all

Sorry for the slow answer, I only read the daily-digest version of the
group.

To be sure, you are right, I get these CYMI for a great price! One big
reason why QRP Labs kits are such low cost is because I work hard on
finding the best pricing for all the components. It all adds up. When I
make the BPF kits I make 3,000 at a time...
which means 6,000 trimmer caps... it does help with bringing the price down
:-)

I can make some inquiries and see if I can get a smaller quantity. How many
do you need? The lettering on the top of the capacitor shell reads "CYMI"
and under that, "FS".

I found these capacitors to be decent quality and very reliable, though of
course you can always melt something by over-heating during soldering, but
generally I have never had that problem.

During the development of the BPF kit I first tried this style of capacitor:

In my opinion they were horrible...
1) they melted very easily during soldering
2) they were not easy to adjust with a standard screwdriver - I guess some
special tool is preferred
3) You cannot see what is going on inside that small blob of plastic - so
making adjustments is horrible

The latter point is important. With the CYMI capacitors used in the BPF kit
you can physically see the angular displacement of the fixed and movable
sets of plates. The reason this is important is because often in the
circuit you have other components all with tolerances, particularly
inductors - which have quite some variation depending on how you wind them
etc. When everything is installed, and you peak the BPF or try to adjust
the VFO limits or whatever - if the capacitor plates are fully open, or
fully closed, you know something is wrong. Likely it is necessary to add or
remove a turn of wire on a toroid inductor somewhere. I give this advice on
all my kits. With the CYMI capacitors you can SEE what capacitance it is
set to (approximately). If it is at either the two extremes, you know
things are not optimally adjusted, and have to take other remedial actions,
on the inductors.

Those tiny 6mm encased plastic trimmers are cheaper. But they didn't match
my idea of what quality I wanted for the BPF kits. That is why I chose the
more expensive CYMI ones.

73 Hans G0UPL
 

Hi again all

I made inquiries through my supply chain. I can get a few hundred of these
30pF CYMI trimmer capacitors and make them available in the QRP Labs shop
price $2.50 for 10. This is not a USA source.
They would ship from Japan like the rest of QRP Labs stuff. Would this
help?

73 Hans G0UPL

On Wed, Nov 29, 2017 at 9:06 AM, QRP Labs <hans.summers@...> wrote:

Hi all

Sorry for the slow answer, I only read the daily-digest version of the
group.

To be sure, you are right, I get these CYMI for a great price! One big
reason why QRP Labs kits are such low cost is because I work hard on
finding the best pricing for all the components. It all adds up. When I
make the BPF kits I make 3,000 at a time...
which means 6,000 trimmer caps... it does help with bringing the price down
:-)

I can make some inquiries and see if I can get a smaller quantity. How
many do you need? The lettering on the top of the capacitor shell reads
"CYMI" and under that, "FS".

I found these capacitors to be decent quality and very reliable, though of
course you can always melt something by over-heating during soldering, but
generally I have never had that problem.

During the development of the BPF kit I first tried this style of
capacitor:

goodman/GKG60015/SG9035-ND/262545
In my opinion they were horrible...
1) they melted very easily during soldering
2) they were not easy to adjust with a standard screwdriver - I guess some
special tool is preferred
3) You cannot see what is going on inside that small blob of plastic - so
making adjustments is horrible

The latter point is important. With the CYMI capacitors used in the BPF
kit you can physically see the angular displacement of the fixed and
movable sets of plates. The reason this is important is because often in
the circuit you have other components all with tolerances, particularly
inductors - which have quite some variation depending on how you wind them
etc. When everything is installed, and you peak the BPF or try to adjust
the VFO limits or whatever - if the capacitor plates are fully open, or
fully closed, you know something is wrong. Likely it is necessary to add or
remove a turn of wire on a toroid inductor somewhere. I give this advice on
all my kits. With the CYMI capacitors you can SEE what capacitance it is
set to (approximately). If it is at either the two extremes, you know
things are not optimally adjusted, and have to take other remedial actions,
on the inductors.

Those tiny 6mm encased plastic trimmers are cheaper. But they didn't match
my idea of what quality I wanted for the BPF kits. That is why I chose the
more expensive CYMI ones.

73 Hans G0UPL
 

On 11/28/2017 11:29 PM, Hans Summers wrote:
Hi again all

I made inquiries through my supply chain. I can get a few hundred of these
30pF CYMI trimmer capacitors and make them available in the QRP Labs shop
price $2.50 for 10. This is not a USA source.
They would ship from Japan like the rest of QRP Labs stuff. Would this
help?

73 Hans G0UPL


Hans,

I've placed my order and hope I'm first in line to respond with
an order.? :-)

Have you put them into a VFO to test their temp coefficient?
Hopefully you have a datasheet to share with the group.

There are a lot of good temp coefficient caps that have gone
the way of reel-to-reel tape and other technology.? I'm hoping
that the cap is good enough for freq setting applications.

Thanks for helping the group.

chuck, k7qo
 

All

I have added this item to the QRP Labs shop, see


Price is $2.50 for a pack of ten of the 30pF trimmers, the same model used
in the BPF kit and the QCX kit


Shipping for QRP Labs items is a weight-based starting from $4.30.

There is a note on the ordering page: since it will take around 1-2 weeks
for the QRP Labs shipment office in Japan to receive stock of the trimmer
cap, shipping won't happen immediately.

73 Hans G0UPL

On Wed, Nov 29, 2017 at 9:29 AM, QRP Labs <hans.summers@...> wrote:


Hi again all

I made inquiries through my supply chain. I can get a few hundred of these
30pF CYMI trimmer capacitors and make them available in the QRP Labs shop
price $2.50 for 10. This is not a USA source.
They would ship from Japan like the rest of QRP Labs stuff. Would this
help?

73 Hans G0UPL


On Wed, Nov 29, 2017 at 9:06 AM, QRP Labs <hans.summers@...> wrote:

Hi all

Sorry for the slow answer, I only read the daily-digest version of the
group.

To be sure, you are right, I get these CYMI for a great price! One big
reason why QRP Labs kits are such low cost is because I work hard on
finding the best pricing for all the components. It all adds up. When I
make the BPF kits I make 3,000 at a time...
which means 6,000 trimmer caps... it does help with bringing the price down
:-)

I can make some inquiries and see if I can get a smaller quantity. How
many do you need? The lettering on the top of the capacitor shell reads
"CYMI" and under that, "FS".

I found these capacitors to be decent quality and very reliable, though
of course you can always melt something by over-heating during soldering,
but generally I have never had that problem.

During the development of the BPF kit I first tried this style of
capacitor:

GKG60015/SG9035-ND/262545
In my opinion they were horrible...
1) they melted very easily during soldering
2) they were not easy to adjust with a standard screwdriver - I guess
some special tool is preferred
3) You cannot see what is going on inside that small blob of plastic - so
making adjustments is horrible

The latter point is important. With the CYMI capacitors used in the BPF
kit you can physically see the angular displacement of the fixed and
movable sets of plates. The reason this is important is because often in
the circuit you have other components all with tolerances, particularly
inductors - which have quite some variation depending on how you wind them
etc. When everything is installed, and you peak the BPF or try to adjust
the VFO limits or whatever - if the capacitor plates are fully open, or
fully closed, you know something is wrong. Likely it is necessary to add or
remove a turn of wire on a toroid inductor somewhere. I give this advice on
all my kits. With the CYMI capacitors you can SEE what capacitance it is
set to (approximately). If it is at either the two extremes, you know
things are not optimally adjusted, and have to take other remedial actions,
on the inductors.

Those tiny 6mm encased plastic trimmers are cheaper. But they didn't
match my idea of what quality I wanted for the BPF kits. That is why I
chose the more expensive CYMI ones.

73 Hans G0UPL
 

On 29/11/2017 6:04 PM, chuck adams wrote:

Have you put them into a VFO to test their temp coefficient?
Hopefully you have a datasheet to share with the group.
Farhan used the same trimmer in the analogue vfo version of the BITX40. If you changed the fixed capacitors for good NP0, it was quite good but in my opinion the inductor stability is much more important.
I don't usually use toroids in vfo's. It's difficult to wind and get the winding taught. In the old days we used to say put the coil former in the fridge and the wire in the oven and then wind the coil as tightly as possible. That with polystyrene caps made a stable 23MHz vfo.
I am interested to see what I can achieve with my NC40 build. I only have 6 material for the core. Hand winding a vfo for 2.1MHz on a straight former is of course much more difficult than at 23 MHz.

I add my thanks to Hans for making them available.

73 Brian VK4BAP

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