C-type or Type-C
6 minute read
November 2025
You learn something new every day, that's what they tell us. I discovered something this week that really took me by surprise; that whilst I knew about C-type connectors, I was to learn that there is another coaxial connector known as a Type-C.
For some time now, the main hallway in our house has been much narrower than my long-suffering and understanding wife would like it to be, as it is full of Racal hardware dating back to the early 1960s. Whilst some of it belongs to me, most of it belongs to a couple of clients and for the best part of 2025, I have been steadily working my way through RA17s, MA79s and MA350s to list but three. And the hallway is yet no clearer than it was six months ago. A couple of weeks ago, during a lull in the work, I decided that I would tackle an RA17L that one of my clients had sent to me. As I can almost do these in my sleep, I figured that as well as getting one item out of the way, it would be quite a relaxing diversion. I was wrong!
As can be seen in the above photograph, this particular RA17L was actually an RA17L-2, which according to various sources is an RA17L with the Burndept aerial connector replaced with a UG connector. The problem here is two-fold. Firstly, there is no such thing as a UG connector. That's not strictly true. 'UG' on it's own does not identify a unique connector. UGxxx on the other hand, where xxx is a three-digit number will identify a connector ... one of many, depending on the numbers. Secondly, I have yet to find an Items list peculiar to the RA17L-2 which identifies the UG connector, and I seriously doubt such a list exists.
I will be honest, I made a mistake. Looking at that aerial connector, I identified it as a C-type connector, and herein lies a problem. C-types may have been popular once, but not so much these days. To that extent, they are not easy to come by, and when you do find a supplier, they tend to be a bit on the pricey side. Being keen to maintain authenticity, my client said he would cover the cost of the mating part if I sourced it ... which I did.
I bought a pair of plugs, one for the client and one for myself. The part was advertised as a C-Type Transradio Greenpar connector type BLB71 with a cable-entry that will take RG213, ... and the price was reasonable. Actually a search for 'Greenpar BLB71' only returns that particular listing. Anyway, the connectors arrived still in Greenpar's sealed packaging. Examining the body of one of the connectors, I found GE 27519 C1, which confirmed them as Greenpar C-Type plugs for RG-213 coax. But something isn't right here. See the photograph below.
The cable-entry will indeed take RG-213 snuggly and the connector body fits the AE socket on the rear of the RA17L-2. But the solder bucket on the end of that centre pin is tiny. It would take Sooty's magic-wand to fit an RG-213 centre conductor in there! Whilst the two PTFE parts fit the centre pin, the rest of the parts are clearly compatible with RG-213 or similar. I can't remember ever seeing a cable that size with a centre conductor so small. Until I can prove otherwise, I'm tempted to say that these connectors might have been incorrectly packed. There's nothing on the sealed packaging to denote the Greenpar part number, but it may be that something went wrong when they were packed, such that the wrong centre-pin and PTFE parts (for RG-58?) were included. I don't think for one minute that this is the fault of the seller.
It was always my intention to make up a small adapter cable from C-Type to BNC. The mating dimensions of the centre-pin were correct, and they were definitely C-Type connectors, so until I got my hands on a C-Type plug compatible with RG58 or RG213 I decided to improvise and make up a temporary adapter for myself. My client would eventually get the real thing. Fortunately I had a couple of wide-bore BNC plugs which would take RG-213. In order to interface the centre-pin to the centre conductor of my length of RG213 it was necessary to cut away 6 of the 7 strands of the centre conductor ... talk about a bodge! It worked, but there was still a problem.
There was a connectivity issue. Although my bodged adapter appeared to connect to the AE socket, the receiver appeared deaf, and this was after I had refurbished and tested all the individual modules that made up this particular RA17L. Everything had been pointing towards a very sensitive receiver ... only it was deaf ... why? Wiggling my adapter cable brought the receiver to life. Examination of the AE connector on the chassis revealed the problem. Like I said, I had made a mistake. What I initially took to be a C-Type connector, apparently wasn't. The centre receptacle was significantly wider than the C-Type centre pin.
As a temporary workaround I replaced the coax from the input attenuator to the AE connector with one with a shielded in-line BNC female. Such is the sensitivity of this receiver, it was impossible to make meaningful signal-to-noise measurements using a coax lead with flying leads on one end.
After completing all my commissioning tests and confirming that this particular RA17L-2 is indeed incredibly sensitive ... that is, the S/N+N figures are 28dB for 1uV of CW and 24dB for 3uV of AM, I returned to searching for a mating part for the AE connector. This time, I must have worded my search correctly and came up with UG-573B/U as an RG213 compatible connector. Refining the search further identified a UG573B/U as a Military-grade Type-C 50-ohm connector. Note that this is NOT a C-Type connector. I was even able to get my hands on a couple (from Germany). See the photograph below.
Below is a photograph of my two home-made adapters. The top one is the Suhner Type-C connector. Side-on it looks identical to the Greenpar C-Type below it.
Finally, on the left is a photograph showing the 'business ends' of the Type-C connector on the left and the C-Type on the right. Note that the ONLY difference is the diameter of the centre pin.
My client will therefore receive a brand new, unused Suhner UG573B/U connector along with his refurbished and realigned RA17L-2.
For some time now, the main hallway in our house has been much narrower than my long-suffering and understanding wife would like it to be, as it is full of Racal hardware dating back to the early 1960s. Whilst some of it belongs to me, most of it belongs to a couple of clients and for the best part of 2025, I have been steadily working my way through RA17s, MA79s and MA350s to list but three. And the hallway is yet no clearer than it was six months ago. A couple of weeks ago, during a lull in the work, I decided that I would tackle an RA17L that one of my clients had sent to me. As I can almost do these in my sleep, I figured that as well as getting one item out of the way, it would be quite a relaxing diversion. I was wrong!
As can be seen in the above photograph, this particular RA17L was actually an RA17L-2, which according to various sources is an RA17L with the Burndept aerial connector replaced with a UG connector. The problem here is two-fold. Firstly, there is no such thing as a UG connector. That's not strictly true. 'UG' on it's own does not identify a unique connector. UGxxx on the other hand, where xxx is a three-digit number will identify a connector ... one of many, depending on the numbers. Secondly, I have yet to find an Items list peculiar to the RA17L-2 which identifies the UG connector, and I seriously doubt such a list exists.
I will be honest, I made a mistake. Looking at that aerial connector, I identified it as a C-type connector, and herein lies a problem. C-types may have been popular once, but not so much these days. To that extent, they are not easy to come by, and when you do find a supplier, they tend to be a bit on the pricey side. Being keen to maintain authenticity, my client said he would cover the cost of the mating part if I sourced it ... which I did.
I bought a pair of plugs, one for the client and one for myself. The part was advertised as a C-Type Transradio Greenpar connector type BLB71 with a cable-entry that will take RG213, ... and the price was reasonable. Actually a search for 'Greenpar BLB71' only returns that particular listing. Anyway, the connectors arrived still in Greenpar's sealed packaging. Examining the body of one of the connectors, I found GE 27519 C1, which confirmed them as Greenpar C-Type plugs for RG-213 coax. But something isn't right here. See the photograph below.
Does that centre pin not look a bit small?
The cable-entry will indeed take RG-213 snuggly and the connector body fits the AE socket on the rear of the RA17L-2. But the solder bucket on the end of that centre pin is tiny. It would take Sooty's magic-wand to fit an RG-213 centre conductor in there! Whilst the two PTFE parts fit the centre pin, the rest of the parts are clearly compatible with RG-213 or similar. I can't remember ever seeing a cable that size with a centre conductor so small. Until I can prove otherwise, I'm tempted to say that these connectors might have been incorrectly packed. There's nothing on the sealed packaging to denote the Greenpar part number, but it may be that something went wrong when they were packed, such that the wrong centre-pin and PTFE parts (for RG-58?) were included. I don't think for one minute that this is the fault of the seller.
It was always my intention to make up a small adapter cable from C-Type to BNC. The mating dimensions of the centre-pin were correct, and they were definitely C-Type connectors, so until I got my hands on a C-Type plug compatible with RG58 or RG213 I decided to improvise and make up a temporary adapter for myself. My client would eventually get the real thing. Fortunately I had a couple of wide-bore BNC plugs which would take RG-213. In order to interface the centre-pin to the centre conductor of my length of RG213 it was necessary to cut away 6 of the 7 strands of the centre conductor ... talk about a bodge! It worked, but there was still a problem.
There was a connectivity issue. Although my bodged adapter appeared to connect to the AE socket, the receiver appeared deaf, and this was after I had refurbished and tested all the individual modules that made up this particular RA17L. Everything had been pointing towards a very sensitive receiver ... only it was deaf ... why? Wiggling my adapter cable brought the receiver to life. Examination of the AE connector on the chassis revealed the problem. Like I said, I had made a mistake. What I initially took to be a C-Type connector, apparently wasn't. The centre receptacle was significantly wider than the C-Type centre pin.
As a temporary workaround I replaced the coax from the input attenuator to the AE connector with one with a shielded in-line BNC female. Such is the sensitivity of this receiver, it was impossible to make meaningful signal-to-noise measurements using a coax lead with flying leads on one end.
After completing all my commissioning tests and confirming that this particular RA17L-2 is indeed incredibly sensitive ... that is, the S/N+N figures are 28dB for 1uV of CW and 24dB for 3uV of AM, I returned to searching for a mating part for the AE connector. This time, I must have worded my search correctly and came up with UG-573B/U as an RG213 compatible connector. Refining the search further identified a UG573B/U as a Military-grade Type-C 50-ohm connector. Note that this is NOT a C-Type connector. I was even able to get my hands on a couple (from Germany). See the photograph below.
Now, that centre pin looks much better!
Below is a photograph of my two home-made adapters. The top one is the Suhner Type-C connector. Side-on it looks identical to the Greenpar C-Type below it.
Type-C Vs C-Type.
Finally, on the left is a photograph showing the 'business ends' of the Type-C connector on the left and the C-Type on the right. Note that the ONLY difference is the diameter of the centre pin.
My client will therefore receive a brand new, unused Suhner UG573B/U connector along with his refurbished and realigned RA17L-2.