Excellent video.. Thanks!

I have a IFR 1200 Super S. When I press 2nd and track I just get an option for duplex hi or low. I just got this unit and I don't know if it's working correctly. Do you know any one that I could ask about this?

What if I use all six notches in series, ie use one whole duplexer on RX and another one on TX ?

I have a IFR 1200s and would love to see how its used to tune a band pass and band reject set of cavities. I dont know a lot about this IFR

Mobile DUPLEXERS must be tuned using proper ports. They have LOW and HIGH sections for a reason, you can NOT change this, due to the internal probe locations on the internal center 'probe'. Low side must be tuned for the LOWEST frequency, and the HIGH tuned for the highest. Most UHF repeaters use a 5 MHz. split. These duplexers are the cause of most site owners demading ferrite isolators on transmitters for all repeaters active at the site. Harmonics are a problem with dense R.F systems co-located on the tower.

i don't have a tracking generator. nor can i get my hands on one. i do however have access to a "rf-explorer" (hand held spectrum analyser) ofcorse i have an wattmeter and a source (HT 1 or 5 watts) is it posible to send the signal you want to filter out trough the cavity's and with the watt meter on the antenna side see where the dip is? (turning the screws on the duplexer) just a quick thought, i have to tune one soon, and i don't have the money to buy a tracking gen (if i had i would :) ) thanks for your time Milan

@Geewhiz811

8 жыл бұрын

+milan hofman In a pinch you can accurately tune a notch and bandpass/band reject duplexer using two portable radios. I have done it using the receiver on one portable and using the other as a transmitter. With this method you ideally want to have some attenuation in line with the transmitter to knock it down. Something like 15 to 20 dB. Another method that is fairly cheap and works extremely well is a sensitive receiver and a broadband noise source. There is a company who makes a wide array of noise sources ranging from individual diodes to complete modules. Here is the link: www.noisewave.com/products.html A stable source of broadband noise is extremely useful and in many ways is a great low cost substitute for a tracking generator. If you want to get really cheap for a noise source you can take a zener diode and precisely bias it to the point between its conduction and cutoff point it will create a whole bunch of noise but it will need to be amplified to be useful.

@milanssite

8 жыл бұрын

i found this unit on eBay, but i can't find readable specs,. www.ebay.com/itm/172024249640 do you know how much "power" these things usually put out? i want to measure it with an RF explorer but i really don't want to fry it! (its not mine you see...) thanks for your help so far. :) milan hofman

@Geewhiz811

8 жыл бұрын

+milan hofman I just took a look at the noise source, it looks to be a very good deal if it is what it claims to be. Noise sources do not put out anywhere near the power that would damage a receiver so you don't have to worry about that.

@milanssite

8 жыл бұрын

+KC2IRV well.. the RF explorer dies at +5dbm... i just order it prior to your message :P as i said im a bit scared because its not my equipment ill probably start with two antennas, and a few feet of separation ;-) if the response is straight enough ill just use that :) thanks for all the help kind regards, Milan

TUNING UNDER R.F POWER, CAUSES ARCING IN TRUE DUPLEXERS, THE MOBILE TYPE HAS NO CONTACT WITH THE INTERNAL STRUCTURE, THEY ROTATE THROUGH NYLON OR TEFLON SLEEVES. THE ONLY CONTACT MADE IS THROUGH THE COVER.

MOBILE DUPLEXERS ARE NOTORIOUS FOR FAILURE TO NOTCH OFFENDING SIGNALS, AND ALL TOO OFTEN, PEOPLE HAVE NOT LOOSENED THE LOCK NUT BEFORE TRYING TO ADJUST THE SCREWS, BREAKING THE SCREWS. I ALWAYS USE A LOAD ON THE UNTUNED/OPEN PORT, TO MAINTAIN PROPER PORT IMPEDANCE AND TUNING.

@plop55

4 жыл бұрын

With the proper length cable, which is what is there in the video, a load on the end will not give false readings.

PLACE THE LOAD ON THE PORT, NOT THROUGH A CABLE. YOU ARE ADDING IMPEDANCE TO THE TUNED CIRCUIT, GIVING FALSE READINGS.

@AECRADIO1

4 жыл бұрын

THE CABLE IS ADDING TO THE UNTUNED PORT. YOUR NOTCH MIGHT CHANGE DRAMATICALLY BY THAT LENGTH OF CABLE.