Here is a great and cheap diplexer for 20 to 500MHz and 700/800MHz

[prcguy]

With all the high gain repeater type antennas I have for every band, the antenna system I built for my wide band Icom R-8600 is a dual Discone system with one Discone covering roughly 100 to 512Mhz and the other covering 700MHz through about 2.4GHz. Its really hard to find a diplexer to combine these frequencies and I've bought a few over the years but they are really expensive new and don't come up used on Ebay very often. In fact I didn't use one on my dual Discone system simply because the diplexer was too valuable to leave up on the tower.

I recently found another diplexer on Ebay that advertises 20 to 508MHz on one port and 518 to 1300Mhz on the other port, nearly perfect for my needs and its only $35 with shipping from Israel. My Ebay diplexer arrived today and it was on the network analyzer about 30 seconds later. Its got very low loss from 20MHz to about 500MHz then it starts rolling off where it has about 6dB loss at 512Mhz. On the other port it works fine from about 520Mhz to over 2GHz.

For those that don't have much T band activity in your area this would be an excellent and cheap way to combine a lower frequency Discone to cover roughly the 100MHz through 500MHz, then a 700/800MHz gain type antenna or a small Discone that covers 500MHz and up. These K&L diplexers probably ran in the $500 to $1k range new. The Ebay seller has several more of these and it takes a few weeks to get it but for $35 its worth the wait.

K&L 5IZ10-20/X1300-0/0 Diplexer 518-1300MHz 20-508MHz | eBay

Our team will be here to support you all the way from purchasing to the arrival of your item. An item that does not function as intended and is not fully operational. For parts or not working. An item that has been used previously.

www.ebay.com

 

[rogress]

Thanks for the post. I grabbed one of those since its a good price. I would like to do something similar instead of swapping antennas each time. Can you tell me what you are using for your two discones?

 

[vagrant]

Are the ports marked? I can sweep it easy and figure it out which is which, but curious. I ordered one anyways. By the way, what is the loss on these? Also, are those SMA connectors or Mini-UHF? It looks like it might be a little bigger than SMA.

This price is pretty good and I'm figuring...well I did just order another one. Ahh...I see someone ordered another one too. It must have swept well.

 

[prcguy]

The ports are marked. SMA connectors, the diplexer is much smaller than it looks in the ad. I warned the seller I am posting good things about his item and not to be surprised if they sell out quickly.

Are the ports marked? I can sweep it easy and figure it out which is which, but curious. I ordered one anyways. By the way, what is the loss on these? Also, are those SMA connectors or Mini-UHF? It looks like it might be a little bigger than SMA.

This price is pretty good and I'm figuring...well I did just order another one. Ahh...I see someone ordered another one too. It must have swept well.

 

[eorange]

Looks like the enclosure has seen some action.

 

[prcguy]

My low freq Discone is a military unit made by Astron Wireless and covers about 116MHz on up. Its got a boat load of elements, at least 12 for the disc and 12 for the cone. The high freq Discone is an all stainless steel solid rod unit from Maxrad, I think its rated either 300 to 2400MHz or 400 to 3200MHz, I forget which and its got at least 12 elements per section. They both have about 6ft of low loss coax to some filters then preamps for each band on my tower.

The preamp box also has a passive VHF low band input fed from a military COM201B 30-90MHz ground plane using a 30-90/100-512MHz split diplexer tapped into the output of the low freq preamp. There are also 18GHz rated coax bypass relays that will bypass the filters and preamps routing the Discones right to the final diplexer when power is removed. Go to post #72 in this thread to see the latest version of the tower mounted box of goodies.

prcguy's mast mount filter/preamp/diplexer thingee

The way I checked the whole chain from antenna and down where to measure the signal strenght from a couple of other towers, that I also managed, when the site where first installed and then keep a record of all values of the site each time a site check where done. That way I could also see if...

forums.radioreference.com

Thanks for the post. I grabbed one of those since its a good price. I would like to do something similar instead of swapping antennas each time. Can you tell me what you are using for your two discones?

 

[vagrant]

They arrived today. I expect this will be a radio project weekend, as I need to paint antenna things as well. LDF4-50A will feed down into the shack. I will compare the two with an analyzer on loan from a friend. I expect minimal difference.

The size is 3.5" x 1" x 2", not including the SMA connectors. This will work very nice for home and remote use.

 

[vagrant]

The seller has one more.

K&L BANDPASS FILTER 51Z10-20/X13000/0 | eBay

Our team will be here to support you all the way from purchasing to the arrival of your item. An item that does not function as intended and is not fully operational. For parts or not working. An item that has been used previously.

www.ebay.com