10W Micro-Diplexer for 2m / 70cm
Here’s a small 2m / 70cm diplexer that is good for up to 10W of power, perfect for working satellites with a HT. The design comes from KI0AG and was originally published in the November-December 1997 AMSAT Journal. It consists of two Chebyshev low-pass / high-pass filters designed for the 2m and 70cm Amateur Radio bands. To keep costs down, coax is soldered directly to the board and you can use heatshrink or the Yagi boom itself as a case. Slots are provided for zip-tie restraints. It does use surface mount components, although they are fairly large (1206 and 1008). This would be a great project for getting your feet wet with SMD work. The board itself is available from OSH Park (US cost is $6.05 shipped for 3 boards as of Feb. 2015) and the BOM is available from Mouser. Using the components listed below, this design is good for up to 10W of power. Keep in mind that you will receive 3 boards from OSH Park, and the Mouser BOM only has the components to build one. Up the BOM to 3 and build some with some friends!
What You Need
Micro-Diplexer Schematic
Thanks for making your design available. I really like the convenience of the parts ordering links you provided. I look forward to building an antenna and playing with the satellites!
Why three holes each for radio, 70cm, 2m ?
(1) shield
(2) center conductor
(3) ???
Two for shielding, one for the center conductor.
I’m just wondering, is this circuit below from you on ebay?
http://www.ebay.com/itm/Diplexer-for-2m-70cm-RTL-SDR-PMR-radio-HAM-radio-/182377855426?hash=item2a769139c2:g:3gEAAOSw44BYRSpY
Looks really similar to this one, what’s more, the same schematic diagram. Are you selling this on ebay too? Nice design anyway.
Holland Diplexer splitters have been designed for residential and commercial applications.
Could you please post a picture of what this looks like with the components soldered to the board? I’m totally new to this, and just want to make sure I’m putting everything together correctly. Thanks!
Thanks for publishing the boards and BOM. I just soldered up the first of three. Now I need to build the antenna and work some birds. I’ve never worked satellites before so this should be fun!
What about the coils, air wound, core wound , wire size, diameter?
Pls share details if possible with pictures
Good morning from India.Well designed PCB …Full assembled Mini V/ U Duplexer want to purchase….fr personal use.
How much cost & Postal charges to send to India..?? as capacitor available but I don’t have any facilities to measure the coil inductence..Plse help …. Online available ?? if Yes which one? 73 : Anand / Call Sign : VU2 AGJ Ahmedabad, Gujarat.India.
Thank you for sharing this. I’ve just put 2 together and will be giving away the 3rd to a club member. Can’t wait to work some birds!
I observed , when I transmit on vhf ,50% loss read on swr meter,but,when I transmit it shows 7 to 8 what’s while my Max power is 5 watt.its Baofenf 5vr. Without duplexer,it gives the result ok.question is why transmitted power incresed at uhf when using duplexer inbetween.its strange but it is..brand new swr power meter I have used Nissei RS40
What size coax is this meant for? Rg58 seems too big.
What do I need as far as a part number to give OSHPARK.
I would like to get the Micro-Diplexer for 2m/70cm board. Not sure how to work there site?
Thanks for any info.
Lyle
I just ordered the Mouser BOM and they told me that the part number 77-VJ1206A4R7CXAPBC was backordered for a year (yes a year). They recommended replacing it with 581-12065A4R7C. They have plenty of the replacement in stock as of this post. 05/16/2018
I’ve made two of these and each time measure 0 ohms across C4 when the board is complete. Is this normal?
Do you have a PCB mount BNC connector recommendation for this diplexer?
Thanks for this. Nice and simple, and no baked-in connectors that I don’t need. Looking at the BOM today, though, the 4.7pF caps are marked “backordered” and also “Manufacturing delays have been reported on this product”. Specs for SMD components still bamboozle me (I am just getting my feet wet here), so I wonder if you might be able to suggest an alternative from Mouser’s inventory? Thanks!
Are the specific 4.7pf caps specified in the BOM critical? Those seem to be out of stock with long lead times. Both mouser and digikey have a similar part with a slightly different part number though.
Hello KW4FB,
This is just to let you know I’ll be using your excellent duplexer in Brazil and most likely in Paraguay.
73,
Luciano PT9KK
How do you calculate this? I have a new found interest in radio, but am as of yet not very knowledgable. I would need one to combine 70 cm and 35 cm. How do I calculate which inductance/capacitance values I need? (Someone less curious might just ask which components to buy, but I actually want to learn something in the process.) I realise the setup looks strikingly similar to a filter of sorts, however I know too little about filters for that realisation to be of any use either. Do you have any suggestions of where to read up on the subject?
Hi
I have a little question, what kind of PCB SMA have you used, I can’t see them in the BOM list
Thanks for making this available. What type of coax was this designed to mechanically accommodate?
Thanks,
73’s
Jim N4WFP
Are the series inductors on the 2M side the main power limiting component?
Can you publish this layout with an option to populate sma connectors instead of soldering the coax directly ?
so… the order sheet that comes up looks like qty 10 parts total caps/coils.
the boards are qty 3 that come shipped for $6 ish.
if i read this all correctly, then ill need to order x3 on parts each to build all 3 ckt boards correct?
jimmmyg
Nice build to have fun with.thanks for the Info de K5MPH…….
This is fantastic – thanks very much for sharing your design. I’ve picked up parts for two from Mouser for now and will keep the third board for who-knows-what in the future.
Do you have a recommendation for coax? I don’t have any to cannibalize right now so I may pick up several short-ish runs of BNC-terminated RG-?? And cut them in half to finish off the build. I’ll most likely be sticking this into my Arrow’s boom.
73 DE VE3XGS
Thank you!!1
Hi
Do you know if a pc boar is available for a duplexer? I ordered the pcb and components for your diplexer.
Thanks Karl K2CWT