Introduction.
Truth be known a IC9700 may not be in many peoples radio budget. So as an owner of the IC9100 with a (VK4AMG RefGen 1V4, ) as well as several upgrades and very happy with its performance, the decision to add the only item the IC9100 missed, a pan-adapter (this radio is a shack rig, never goes on field days). Well the first thing was to find one, budget AU$100 approximately. So I hit the net, typed in pan adapter IC9100 and Bob’s KD2C (David https://kd2c.com ), had this little PC board which could accommodate the four bands HF,VHF,UHF and SHF.
Figure 1- PAT-V-9100 Module
Pat V arrived 2-3 weeks later fully complete with required accessories. During Easter 2019 over a couple of cups of tea the PC board was fitted into the IC9100. All that had to be done was solder red and black power wires in place, one RG-316 output coax to one end, four RG-316 coax cables to the other end, job done.
Next find all the soldering points on each band to connect these coax cables, with the help of the extremely well documented paperwork from KD2C, they were all found. After a few more cups of tea the soldering was done, to my amazement the points to solder required less effort than imagined leaving me with that feeling we all get after a successful outcome.
Power to the board was also well documented, with a quick connection to a 10 volt track. A hole needed to be drilled in the chassis for the SMA outlet, for the SDR. I tidy the cabling replaced the covers and pushed the all important power button. No smoke, all powered up as per normal and the PC connection into the SDR dongle, all worked to plan. Also, most other types of radios are supported by David’s boards.
Review.
When the kit was assembled and installed (extensive detailed instructions provided), it was time to ask for a check of connections and the operation of the radio with the PAT fitted.
When asked to review the installation, George VK4AMG was pessimistic about the TAP connection points being on the top of the VHF / SHF tuned circuits and doubted if a two stage source/emitter follower could have the required frequency response (to 1300 MHz). The connection from the TAP point to the module by 30+ cm of RG142 coax cable (20+ pF) and the shield connected only at one end also caused concern about detuning and coupling noise into the front end of the receiver.
For the IC9100 a PIN diode switch has been added to the front end of the standard PAT amplifier in attempt to provide automatic selection of the active receiver. There is no termination on the PIN diode switch. A normal value would be conflict with the supposed high impedance of the amp. The DC voltage at most of the recommended tap points is the tuning voltage for the front-end bandpass circuits and is insufficient to provide effective switching of the PIN diodes with or without a terminating resistor.
Figure 2 and 3 show the frequency response of the PAT-V-9100 module with and without biased PIN switches.
Analysis shows the Hi-Z section of the PAT is useful as an IF/RF tap to about 50 MHz. As an RF tap for a VHF / UHF radio the PAT-V-9100 is a 20+ dB attenuator. With any detuning of the RF tuned circuits due connection of the PAT-V-9100, the radio sensitivity is degraded and an externally connected SDR may only show signals of S7 or better.
Figure 2 – PAT-V-9100 Freq Response – No bias on input diodes
Figure 3- PAT-V-9100 One input diode forward biased, Others reverse biased
George has previously used applied PGA-103 LNA modules (Minikits PGA-103 LNA kit or eBay “0.05-4GHZ Low Noise Amplifier LNA RF Broadband Amplifier 23dB High Linearity 5V”) with a SMD attenuator / splitter inserted in the VHF / UHF RF cables or internally in the IC910 23 cm module. In addition to providing a high-performance TAP point, the LNA lifts the performance of the IC910H receiver.
Figure 4- LNA and attenuator providing a 23cm TAP in IC910H
With the red wire connector fitted, I started diagnostics on the UX9100 module with the aim of planning the fitting of the “Chinese” LNA purchased on eBay as a possibility of the basis for VHF & UHF RF taps.
Enthusiasm got the better of me and I fitted one. However, some hours were required to make it go. All due to a dodgy connector on the tap output. Another 15 minutes with the HP Noise Figure Meter proved the tap works like as per the IC910.
The options for combining four of these modules to cover the IC9100 bands are being evaluated and will be published when this project is complete.
After many hours the conversion has been a great success.