BPF Board for PICaSTAR

This is the Band Pass Filter for PICaSTAR. It is part of the second PCB panel, supplied initially in April 2008 and is based on the G6ALU SMD version. The original is by G3XJP.

This is BPF build information, with notes as it is being built by VK3PE

Last updated on April 29, 2009 Update to testing section

April 15, 2009 Jabdog (UK) part numbers for Toko coils added

April 7, 2009: coil winding table for Toko added

4th May, '08: there have been some reports that the unplated holes in the bandpass select end panel, are in fact plated on some PCB's only. Please check your own PCB for this potential problem. Use your beeper to check from one side of the hole to the other. This is a PCB vendor error. You will need to drill these holes out to remove the plating. I am advised that using a drill bit by hand, removes the plating.

Problems ! Disappointingly, there is also a drilling error on the PCB for the BPF. The shield can ground holes for all of the Toko coils are undersize. Before you place any components on this PCB, you will need to drill out all the Toko holes for the CANs ONLY. Use a sharp, preferably new, 1.5mm drill and carefully drill the holes. It is very easy to accidentally drill the wrong holes, so take your time doing this. If you are unsure which holes to drill out, please ask.

Of course, this removes the plating from the holes but it is of no real concern for these holes at this stage. Later, when you fit the angled shields over the bus bars, you will need to tack solder the cans to the bare strip on the top side.

I am advised that a Dremel™ tool can be used to pare the tabs down, to fit in the PCB holes, without having to drill out the PCB.

Hi Glenn, Just a thought...

I find it easier to grind off a bit of the tabs on both your Tokos and mine to get them to fit the hole rather than the other way round. When the cans are off for re-winding it is a matter of seconds only with a Dremel tool and cut off wheel to take enough off for them to fit. I presume you have Dremels down under? A little hand held power tool commonly used in the US; I'd be lost without mine. This preserves the plated through hole.

Cheers, Dan ac6ao / g3ncr

 

Documents are Preliminary ONLY !

(there are some incorrect values shown for the combination of caps in bands 7 & 8, see update)

Bill of Material, updated 020508

Schematic, 020508 Sheet 3 has been updated. Note this file has same name as before !

Overlay updated 020508

040508...NOTE!!!!! The COTO Reed relay MUST be inserted the correct way round as they have a protection diode across the coil. Pin one on the relay is marked with a chamfer (see below) and this end must be towards the Rx input of the PCB. The overlay shows pin 1 orientation also.

 

Toko Coil winding

I used hand wound Toko coils I had made previously. See HOW to do it HERE

VK3PE's winding information for Toko 10K coils. NEW April, 2009 (Excel spreadsheet)

Toko or Slot-10 etc pre-wound coils can also be used of course. Lodestone may also be fitted but a clearance hole under the former is required for the slug I believe. A small hole marks the location for this.

 

Pictures below show the near completed BPF assembly. Shields over the bus lines to be fitted. They will solder to the long sides and the edge of the Toko cans where the copper strip is visible. Coils for the"spare" band are not fitted. In fact this filter is bypassed with co-ax cable. See other pictures.

Also, the bottom is not fitted. The bottom is not supplied with the PCB panel. A double sided piece of blank PCB material is cut oversize with allowance for mounting holes, and is then soldered to the bottom edges when all alignment is completed. The "busbars" on this version are tracks on the PCB with through holes to the FST3126's on the other side.

 

 

 

 

 

 

 

 

 

 

View of the bottom before sides are fitted. The Co-ax cable bypasses the "Spare" band position, for general coverage receive.

View of the inside, with outer PCB's fitted. There are marker lines on the sides to aid soldering them on. There are "fingers" on the left side of the picture which make the connections for the band select lines. NO ferrite beads (FB) had been fitted when these initial pictures were taken. The solder between the side plates and the PCB. There are pads on the main PCB which are marked with a circle around them, to identify where to solder the FB. NOTE: on the sides, there will be a pad that is unused for each band. Only solder the FB to the pad where the track connects to it !

Later......Picture to right was added later and shows a Ferrite Bead (FB) fitted. I might actually fit the FB's to the side pcb pads and run a short wire across to the main PCB. The beads are type FB43-101

 

 

 

 

 

 

 

 

 

Fitting of the IF Trap capacitor. The COTO Reed relay has not yet been fitted.(refer to BOM for details) No diodes have been fitted either on the Rx input. There is provision to fit diodes vertically, between the designators "Rx & Tx", but please note that there should be three 1N4148 diodes fitted in each direction. The board appears to have only provision for two, but this is due to lack of space. To fit the three diodes, two of them must be joined in "mid air". ie stood up and soldered at the junction. I will show this later. If you are using the LPF board on this panel, then the three by two back to back diodes are already on the LPF board.

 

The 10k resistors fit through the end as per original. A bit tricky to solder though ! Check with an ohmmeter when complete, to ensure connections. Note the band select connector which is not on the original version. Otherwise, this version follows the original G3XJP fairly closely. Top shields yet to be fitted.

The co-ax cable to the MR is fitted through the right hand hole. The inner is soldered to a point just inside.The solder pad for this connection on main board is VERY close to the ground points. It might be advised to trim it back slightly with a very sharp knife near the edge or use small file to avoid shorts to the end plate. The co-ax outer is soldered to the bare copper area. You could possibly mount a mini co-ax connector, like an SMA here also if you wanted to, although I have not tried it myself.

 

 

FITTING THE SIDES.

Use the marks on the inside of the side panels to align the main PCB then tack solder each end. Look in the very centre of this picture. The "mark" is ABOVE the main PCB.

It's a little tricky to start with but once you have 2 sides fitted it becomes easier. Don't be tempted at this stage to seam solder all of the joints ! The tacks will allow you to shift the side slightly if needed. Make sure that the top and bottom edges of the side panels align also.

 

Does it work ? Initial testing of 160M through 40M bands shows that it does ! I have to fit more FB's for the other bands.

I have been unable to measure the actual isolation in the "off" mode due to lack of facilities but on my tracking gen/spectrum analyser, it looks good so far. (>80dB which is limit of my set-up) Of course I am still to check and align all the other bands and will do so when more time is available. It draws approx. 13mA from a 12v supply. When testing, make sure only 5v logic is used to enable each band. (see note further down also, to avoid possible damage to one or more of the FST devices !)

Plots of 160M to left, 80M on right. The peak on left is the zero marker. Actual losses measured were 5dB on 160 and 4 dB on 80.

The central shield which will run down the centre of the main PCB is also not fitted, while testing. This shield solders to the strip which can be seen on the PCB and then makes contact with the bottom cover. (Not fitted also). Refer to the G3XJP original drawings for details of the shielding.

I have now made a temporary switch to select the bands while testing. I fitted a connector with an 8x 10k resistor SIP package. (This is just 8 resistors in a package with one end of each connected together. You can use 8 individual resistors of course) The common goes to ground terminal. This keeps the not selected bands OFF. The common of the switch connects with a temporary wire to the 5v supply inside the BPF. This way I can select the bands using the switch, while testing the filters.

NOTE: After this was initially written, I was advised by Jay C. of potential damage to the FST parts. A copy of his email is below.

190408 by email...

Hi Glenn,

I was just reading with interest your build of the new BPF board.

Would you please add a note that, when testing, it is *imperative* to ground the Tx 12V line BEFORE applying power to the Rx 12V point (or vice versa). Failure to do so will almost certainly take out IC1 FST3126 and maybe others. I speak from painful experience...others also.

BTW, it is also important to do this before testing the IF board...although in this case I don't know what damage if any could be caused.

I don't know the reason why IC1 is liable to be destroyed...maybe it is essential that all switch segments need to be terminated...but it happened to me and when I reported this to the group, others, including IIRC Duncan confirmed that I wasn't the first and wouldn't be the last. It might, further, be a good idea to check your IC1 to see that it hasn't happened to you.

In any case, it's a simple precaution and can't do any harm.

ATB Jay


16th June, 2008

Glenn, I was just sending these to a friend and thought you might like to see them also. The BPF brick with 30 metre and IF trap using toroids. Looks like they were supposed to be there! Cheers, Dan

Dan also soldered on SMA connectors.

 

17th June 2008 Details of toroids: (this is NOT an official mod. but is shown for interest)

T50-2 x3 for the thirty meter filter, 16.7 ÁH from the calculator should be 58 turns, but I had to remove two or three from all of them in the event, to get the filter spot on. T68-2 for the IF trap. I dunno how many turns, I just more or less filled it up and then resonated it at 10.7 MHz with the combination of trimmer and fixed mica cap. Ceramic trimmer in this one and air spaced the first time, not a lot of difference.

Toroids that are not full can be trimmed by moving the turns in or out, but that ain't possible when they are pretty much full up of course, as is the case with the 30 metre ones. The main thing is that the much higher Q of the toroids on 30 metres brings the insertion loss down to something reasonable from the more than 10 dB I was getting with the Tokos.

The IF trap gives a nice notch at 10.7 (50 plus dB) and less skewing and distortion of the wanted pass band on 30 as well. For those who don't use 30, which includes most of the SSB mob, it isn't of any interest of course, but I do like 30, myself... The only other thing I altered was to move the IF in / out feed to the 160 metre end with a bit of hard line, it's hidden under the brass strip.

No progress here at all for a couple of weeks, there's been a lot of family stuff to get in the way... Cheers, Dan


 

Re-winding Toko coils (24th March, 2009)

There is some good information on the Yahoo "Picastar-users" group.

Refer to messages # 1599 and #1601, #1591


 

Pre-wound Toko Coils (Jabdog:- supplier in UK)



The Toko coils supplied to me by Jabdog are:-

Toko code {Jabdog code}
154ANS-T1017Z {EZ-1017 }
154ANS-T1012Z {EZ-1012 }
154ANS-T1014Z {EZ-1014 }
154ANS-T1007Z {EZ-1007 }
TKAN - 9448HM {10K-9448 }
BTKANS-9450HM {10K-9450 }

The BTKANS-9445HM is out of stock so I had a BTKANS-9444HM instead and will attempt to re-wind to required inductance!


Total cost for all 25 pieces inc shipping £48.40


Hope this is of some interest.

Regards

Tony G3YIP


 

 

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Web page written by VK3PE, on 20th April, 2008