Batboard

I am looking for a source for the side-mounted MSF N female Panel Mount to UHF-Min Female. I don't want to use a bunch of adapters to do what should be done right But I've struck out looking. The last MSF "repeater" to come in was another remote base that had to be converted - no biggy if you have the panel mount connectors. They didn't have a 2135 key so they pried open the cabinet. All of the mounting holes on the PA are stripped and have to be tapped again. So much for a $375 bargain. LOL. OK. A little elbow grease...

Usually the coax is soldered/crimped directly to the back of the N-female connector and goes to wherever it needs to go. There is no connector on the back of it, just at the other end of the coax. No adapters or other connectors. There are companies on the web that will make this cable to your specifications; you tell them what connectors you want at each end and the type and length of coax, and they send you a custom cable in return for some money.

Why do you want to go to mini-UHF? Where is the other end going?

An alternative is to get an N-female to N-female bulkhead connector, one that has continuous threads on the outside, and two nuts. That lets you attach an N-male to the inside of the cabinet and you use whatever else you need on the other end. You can use RG400 inside the cabinet as it's quite flexible.

The mounting holes in the chassis rails are Metric. The factory screws were self-tapping but you can buy ordinary Metric screws and tap them yourself. The steel is quite soft. Steel or stainless steel pan-head Phillips M6x1x10mm screws cost me about $8 for a box of 100. You can always spray-paint them flat black.

Bob M.

Here are a few Motorola part#'s for jumper cables with a N female panel mount to mini UHF connector:

0112004E09 CBL N PANEL FEMALE TO MINI UHF MALE 9"
0112004E06 CBL N PANEL FEMALE TO MINI UHF MALE 36"
3013943K24 CBL N PANEL FEMALE TO MINI UHF MALE 31"

Excellent info from both of you. Thank you! Do you have a source other than Motorola? I actually like the dual female/female bulkhead plan. All of the cables are RG-142. I am not trying to go to UHF-Mini, its already there. I've purchased three from eBay and the TX always requires a barrel union to mate the the 8" length that goes over to the PA. Similarly, the RX has a 12" or so RG-142 that comes from the bottom of the RX tray and ends in a UHF-Mini. I just thought that this wasn't right -- too many adapters. But I don't know what factory was. If I knew the source I'd replace them all with factory. To the best of my knowledge each began as a remote base.

The transmit from factory came out of the PA to a pass filter which ran across the back of the station. The pass filter was approx. 12" long double female "N" which is why there was only an 8" piece of feed line for the output of the station.
Doug

In UHF base stations, the output of the IPA is an SMA-female coming out of the bottom of the RF Tray. A cable runs from that connector to an N-male, then a barrel adapter, then on via an N-male into the PA. In stations with the internal filter/duplexer, the IPA feeds the 3-section filter and the filter feeds the PA. The barrel adapter takes the place of the input section of the internal filter/duplexer on base stations.

Similarly, in a UHF base station, the N-male output of the PA feeds a low-pass filter and then on via an N-male to the antenna relay which has its own antenna jack. In stations with the internal filter/duplexer, the N-male from the PA feeds the 4-section filter and the filter feeds the TX antenna jack via a short cable: N-male to chassis-mount N-female. On a VHF station there's a peripheral box that contains the low-pass filter and optionally an antenna relay. There might be a mini-UHF female connector on that box to feed the receiver's front end but I've never seen one in person and my manual doesn't tell me what type of connector is there.

For UHF base stations, the receive side is a single coax run from the antenna relay to the SMA jack on the side of the front end. I understand that VHF stations have a mini-UHF-female connector on the front end where all the others used SMA-female. For repeaters, a single cable starts at the RX antenna jack's chassis-mount N-female and ends at the front end.

If the station has a real duplexer mounted inside the cabinet, chances are that's configured to use UHF-female (for 300 MHz or lower) or N-female connectors on everything. Unfortunately Motorola also used UHF connectors on UHF base stations, probably because they had a lot of surplus antenna relays with that connector already on them. But UHF connectors aren't supposed to be very good above 300 MHz.

You haven't mentioned what frequency range or band this station is for, but since you mentioned mini-UHF, I assume it's a VHF station (yes, shame on me) and you want to eliminate the peripheral box, hence the search for adapters. Motorola would have used one cable for base stations and another for repeaters, and that's how you eliminate all the extra adapters.

RG142 is double-shielded teflon insulated RG58-size (0.195 or 0.200 inch diameter) coax with a solid inner conductor. RG400 is identical except it has a stranded inner conductor which will last a lot longer in applications where the cable will be flexed, such as going to the RX input of the front end on the RF Tray.

Bob M.

Thanks Bob,
I even didn't think of the pre and post filters

kcbooboo wrote:In UHF base stations, the output of the IPA is an SMA-female coming out of the bottom of the RF Tray. A cable runs from that connector to an N-male, then a barrel adapter, then on via an N-male into the PA. In stations with the internal filter/duplexer, the IPA feeds the 3-section filter and the filter feeds the PA. The barrel adapter takes the place of the input section of the internal filter/duplexer on base stations.
Bob M.

Then the VHF station is the same. It comes out of the PA to the antenna connector through RG-142 but it states on the parts list that nRG-400 may be substituted.

I hqve a complete crimp set and should prolly just make my own direction connections free of adapters. I don't like adapters. 0.25dB and 0.50dB losses add up quickly enough.

I don't think there was ever an internal filter/duplexer (pre- and post-filter) setup for the VHF stations. They used a real pass/reject duplexer. The barrel connector between the IPA and PA has no real effect on the output power since the power control circuit simply increases the drive from the IPA to make up the difference.

I agree, adapters will add a bit of loss, but so do connectors, so the only way around that is to make purpose-built cables as short as possible with exactly the right connectors at each end. As you've got the crimper, just buy a few feet of RG400 (I've bought it as cheap as $1/ft but last time I checked the going rate was around $1.50/ft for as much or little as you want) and the correct connectors. Just make sure the ferrules (the part you crimp around the two layers of braid) is thin enough for the double layers or it says it's for RG142/RG400. If it mentions LMR195 or RG58, it's NOT the right connector. The outer diameter of the ferrule is the same, but it has a thinner wall to leave room for the 2nd braid. Crimping may also be a bit tight or you may have to release the crimping tool prematurely because of the 2nd layer.

Bob M.

Thanks again, Bob. The MSF 5000 VHF uses external duplexers of ones own choosing. We use Sinclair Q2330e BrBp duplexers that I have already confirmed with Sinclair is only a pseudo BrBp but a high caliber one.

The VHF unit has a rather effective preselector which of course is nothing more than a 4-pole helical resonator. I'm anout to go off topic so I'll start a new thread.