1. Thanks for the video! Did you ever get the video on how to tune the VHF cans? I looked through your videos and couldn't find it. I am interested to see how you did it.

  2. Just a quick question, Why is it that you would use a terminator as a dummy load on the side that you are not working with. We don't do that when we tune our UHF and VHF duplexers here at work, so I was wondering what the difference is or if its better to adopt that practice? We are just learning to do it here and any advice is greatly appreciated.


    BUT—> First of all: THANK YOU !! (You have created a great assortment of training videos that are fabulous!)

    We have several repeaters that are in the process of multiple freq changes, etc… and, not only is it difficult to find local
    dealers who will do decent duplexer "tuning", getting someone to go "on-site" is near impossible. Sending a duplexer in for tuning takes forever, is costly for the shipping part (we were using Fedex to avoid de-tuning units due to mishandling and vibration etc..) After finding your video, I checked the pricing on the Rigol unit, and it seemed very affordable to purchase and have to the ability to tune i "in-house" (or at repeater site).

    Quick Question: I can navigate programming / antenna installation / anything on the "IP" side of things as well as most parts of repeater installation, but have not delved into the measurement side of things much (other than a Bird 43 Wattmeter + a collection of slugs I bought 20+ years ago and the replacement for that — the Telewave 44). In addition to being practical in order to get duplexers tuned in the field… This seems like a great way for me to delve into & learn other areas of radio communication. (at least analog for now — P25 Phase 1+2 /DMR-TDMA / etc… can wait a bit – LOL)

    I just wanted to verify something in the video. Obviously, I am a complete "newbie" just starting to learn how to tune duplexers for our small repeater installations.

    You indicate that the "Transmit" frequency is the higher frequency. and the "Receive" frequency is the lower.

    I am definitely confused — so HELP! LOL

    In the "GMRS World" and in most of our "conventional UHF" (450-470mhz), the separation is 5mhz between tx and rx (in many of our "T-Band" gear, the separation is 3mhz). I know that some "amateur" 70cm repeaters use either a (+5) or (-5) mhz difference for the "input" of the repeater, but for the PW and IG bands, I have only encountered the (+5) coordination/assignment. (Example== repeater "output"/TRANSMIT is: 453.5125mhz — and the "input"/RECEIVE is 5mhz HIGHER at: 458.5125mhz)

    Is that how your example duplexer is tuned in the video?

    In all of the installations we have done in the past, using pre-tuned duplexers ("mobile" style like the Celwave in this video — for all of our "backup" or "in-building" — less critical repeaters that are generally 20-40 watts and not used heavily)

    For our "primary" repeaters / higher power + better performance necessary… especially one of them located on a water tank with many other RF sources nearby (we have 3), we use Quantar or MTR3000 Repeaters with rack-mount larger TX-RX "Vari-Notch" pass/reject style Duplexers or the RFS "black" 6 total cavity rack mount pass/reject style.

    (..wanted to "get my feet wet" on the "mobile" unit first, before delving into the more complex cavities LOL)


    Sorry — just thought of one other question: I heard "squeeking" when you were adjusting the tuning rods on the
    unit in the video. Do you "loosen" the nuts prior to tuning, then tighten up when done?… or… do you just turn the
    rods gently w/o loosening the nuts? (never saw one done in person — but, on the larger bpbr units I've seen done ,
    the tech has generally loosened the "locking" nut during the tuning process, then gently tightened the nut and applied
    some nail polish or other substance to "mark" the positioning and to keep it from vibrating loose. — I was told not to
    use ANY type of "loctite" on the treads under any circumstance.)

    Thanks !

  4. How are you getting such a clean sweep with 0 attenuation to your input when you hook the tracking generator in for the normalize function? At -10db attenuation, I get a clean sweep, but at 0db I get a sweet with -55db spikes and it will not normalize?

  5. Fantastic, very good seeing this video I learned to adjust UHF duplexer, have a rigol DSA 815-TG, would have a step by step manual to sell me ??
    Accompanying this video learned to some axtent just could not keep up at end, referring to the summary and the technical adjustment report. I would also like to watch a video one line of a duplexer to 144 mhz off-set 600khz. thank you. my name Moises – São Paulo Brasil Amater radio prefix my PY2HR. py2hr@hotmail.com.

  6. Many thanks for excellent video.  I looked at your earlier version using the test set.  Is it possible to add "measure loss thru filter" to this DSA815TG version or a separate short video?  Would be helpful for novice users.  Thank You for your efforts.  Paul vk4apn

  7. Great video! Im currently waiting for my very own 815-TG to arrive and trying to study some tuning methods. I would like to see the follow up on that pack of band pass cavitys. Thanks / A curious Swede.

  8. It is a great video it is about time some one made one for the flat pack duplexers.
    I see you upgraded to a very good TG I have one like it and love it.
    Waiting to see your new video.

  9. Hi Steve and Marcus, very well done. From my point of view with 30 + years as a wireless systems engineer, your presentation is very descriptive and represents the overall objective of obtaining cavity filter resonance and rejection. Utilizing the duplex and tracking generator functions contained within a Communications Service Monitor is the best and most effective way of field tuning as dragging a Network Analyzer to the field is not practical, However the Network Analyzer will provide much more precise measurements, at the end of the day the overall differences in the actual measurable resonance and return loss when comparing the results of a service monitor to the results of a network analyzer. Most experienced radio technicians and system engineers have all used a service monitor to tune filters, duplexers and circulators (Isolators) without degrading system performance to the handheld, mobile and base station users.

    Sure a Network Analyzer would be better if scientifically analyzing the results, not to mention the cost of a network analyzer vs the cost of a service monitor make the service monitor the logical and reasonable choice. I have several network analyzers as well as several service monitors and only find myself needing the use of a network analyzer only when designing custom filter's or other components that require extreme precision in order to function.

    Again, you both have done a great job explaining and demonstrating the overall objective of tuning cavities for resonance, rejection and isolation.


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