[DB 404-B Antenna]

Investigating where/how I can replace the dry rotted/cracked phasing harness assembly for my old db 404-B antenna. Any insight would be appreciated.  

[Duplexer Specs... Are these considered acceptable/Good?]

I just purchased the same one.

Pretty good so far.

50watts in 43watts out.

80db of isolation is just as good as my 4 big cans decibel vhf band pass/band reject duplexer. Very impressive.

I like the use of silver plating. Nickle makes a mess out of tx'n uhf.

Great construction and size.

I am glad you posted... I haven't pulled the pin yet and am happy to hear from someone that actually put their hands on it!  Thanks! 

[Duplexer Specs... Are these considered acceptable/Good?]

The specs look pretty decent. I have not seen that brand before, but it appears that he's got pretty good reviews on Ebay from his buyers - with a 100% feedback rating. The only negative comments seem to regard the shipping from Canada taking too long.

 

80dB of isolation is more than acceptable from a 4 can duplexer. Rule of thumb is 30dB per can (per side), but I can see that there are what appears to be some trimmer capacitors - which will sharpen the notches & help isolation. Generally, those are a good thing, but the quality with which the trimmers are built will ultimately decide the useful lifespan of the duplexer. See: http://www.duplexerrepair.com/2016/12/26/trimmer-capacitor-failures-in-decibel-products-duplexers/

 

It appears from the pictures & pricing that they're trying to strike a reasonable balance between quality and price, and they're shooting for the ham and hobby market - and at that price, they should have pretty good response if the quality holds up.

 

Assuming you're going to use it as a lower power repeater duplexer, it looks like it should perform well.

 

 

Thanks for taking a look!  This would be for a GMRS system with 50 watts max.  Thanks again!

[Duplexer Specs... Are these considered acceptable/Good?]

Good Morning on this Memorial Day.  Came across a duplexer brand called "Intermod" model Model: D440N-4, made in Canada, for what seems to be a great price (about 268.00 USD).  I am seeking input from someone knowledgeable about what is considered decent parameters as I just don't know.  Below is what is listed...

 

Electrical Specifications       Frequency Range MHz 406 to 470 Return Loss(min) dB 18 Insertion Loss(nominal) dB 0.6 Isolation(nominal) dB 80 Impedance Ω 50 Tx-Rx Separation (*) MHz 5 Average Power Input (max) W 100

 

 

Thanks in advance, 

Scott

[Kenwood TKR820 - Cheap duplexer vs seperate antennas]

Have been using the tkr820 repeater with a cheap ebay duplexer and old db404 antenna.  I can't say I've been happy with the results as far as usable coverage.  I have been considering removing the duplexer and adding in a tram 1486 (that I have had laying around) as the second antenna. My simple thinking is that maybe the db404 would be the better receive antenna and the Tram would be the better on the transmit side?  Maybe I am expecting too much, I don't know.  Looking for opinions and insight.  Thank you. Scott