Re: [Repeater-Builder] RF Fuses
An article on upgrading a piece of equipment with one of those connectors would be a real good idea for the test equipment page. And if anyone has a couple of photos of that Cushman accessory that would be good to add. In fact, I need one of those for my CE-5. Mike WA6ILQ At 07:39 PM 03/20/10, you wrote: If I remember correctly, Cushman had a box that went in front of their communications monitors. This was a small cast metal box with BNC connectors attached. Inside was a small pigtail fuse between the connectors. The fuse was rated at 1/32 Amp. 73 Glenn WB4UIV At 06:36 PM 3/20/2010, you wrote: Any ideas where I can buy RF fuses, either the actual fuse element or the combination holder/fuse say in a BNC configuration, to portect the input of a spectrum analyzer or service monitor? Dave WB2FTX Yahoo! Groups Links Yahoo! Groups Links
Re: [Repeater-Builder] RF Fuses
How about Making one out of an old polyphaser housing just remove the guts and solder in the pico fuse. Should remain closer to 50 ohms if than putting a couple of chasis mount connectors on a metal box.. tom Mike Morris WA6ILQ wrote: An article on upgrading a piece of equipment with one of those connectors would be a real good idea for the test equipment page. And if anyone has a couple of photos of that Cushman accessory that would be good to add. In fact, I need one of those for my CE-5. Mike WA6ILQ At 07:39 PM 03/20/10, you wrote: If I remember correctly, Cushman had a box that went in front of their communications monitors. This was a small cast metal box with BNC connectors attached. Inside was a small pigtail fuse between the connectors. The fuse was rated at 1/32 Amp. 73 Glenn WB4UIV At 06:36 PM 3/20/2010, you wrote: Any ideas where I can buy RF fuses, either the actual fuse element or the combination holder/fuse say in a BNC configuration, to portect the input of a spectrum analyzer or service monitor? Dave WB2FTX Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links
Re: [Repeater-Builder] RF Fuses
On Sun, 21 Mar 2010, Thomas Oliver wrote: How about Making one out of an old polyphaser housing just remove the guts and solder in the pico fuse. Should remain closer to 50 ohms if than putting a couple of chasis mount connectors on a metal box.. Let's see, we can calculate voltage on the line by reading the SWR or VSWR. I've never read into calculating RF amperage, but I assume that it would be calculating the amperage feeding a fifty-ohm load from the VSWR. Can someone correct me on this please? -- Kris Kirby, KE4AHR Disinformation Analyst
RE: [Repeater-Builder] RF Fuses
Tom, One of the many differences between a Polyphaser and a Huber+Suhner arrestor housing- besides about $200- is that the latter is machined to present a constant impedance. If you've opened up a Polyphaser arrestor, you can see that its design does not lend itself to maintaining a constant impedance; it's basically a box with connectors on each end. While this design may not matter at low frequencies, it does matter at the GHz range for which most service monitors can operate. It is perhaps not a good idea to fabricate a device that can alter the impedances seen by a critical bench test instrument. I do know that the special fused BNC connectors on my R2600D service monitor are designed to avoid an impedance bump. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Thomas Oliver Sent: Sunday, March 21, 2010 8:03 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] RF Fuses How about Making one out of an old polyphaser housing just remove the guts and solder in the pico fuse. Should remain closer to 50 ohms if than putting a couple of chasis mount connectors on a metal box.. tom Mike Morris WA6ILQ wrote: An article on upgrading a piece of equipment with one of those connectors would be a real good idea for the test equipment page. And if anyone has a couple of photos of that Cushman accessory that would be good to add. In fact, I need one of those for my CE-5. Mike WA6ILQ At 07:39 PM 03/20/10, you wrote: If I remember correctly, Cushman had a box that went in front of their communications monitors. This was a small cast metal box with BNC connectors attached. Inside was a small pigtail fuse between the connectors. The fuse was rated at 1/32 Amp. 73 Glenn WB4UIV At 06:36 PM 3/20/2010, you wrote: Any ideas where I can buy RF fuses, either the actual fuse element or the combination holder/fuse say in a BNC configuration, to portect the input of a spectrum analyzer or service monitor? Dave WB2FTX Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links
[Repeater-Builder] RF Fuses
Any ideas where I can buy RF fuses, either the actual fuse element or the combination holder/fuse say in a BNC configuration, to portect the input of a spectrum analyzer or service monitor? Dave WB2FTX
RE: [Repeater-Builder] RF Fuses
Dave, There's nothing special about a fuse to protect test equipment from accidental application of RF. My General Dynamics (Motorola) R2600D uses 1/16 ampere axial fuses behind the antenna and generate BNC connectors, and these are easily replaceable from the front in less than a minute. (Yeah, I made a boo-boo with a mobile radio hooked up wrong, but the fuse did its job and protected the instrument.) I don't know who makes these special connectors, but perhaps you could buy them from GD or Aeroflex and retrofit them to your own equipment. The connectors are designed so that the 50 ohm impedance is maintained when the fuse is in place. The fuses are about the size of a grain of rice. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Dave Sent: Saturday, March 20, 2010 3:37 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] RF Fuses Any ideas where I can buy RF fuses, either the actual fuse element or the combination holder/fuse say in a BNC configuration, to portect the input of a spectrum analyzer or service monitor? Dave WB2FTX
Re: [Repeater-Builder] RF Fuses
If I remember correctly, Cushman had a box that went in front of their communications monitors. This was a small cast metal box with BNC connectors attached. Inside was a small pigtail fuse between the connectors. The fuse was rated at 1/32 Amp. 73 Glenn WB4UIV At 06:36 PM 3/20/2010, you wrote: Any ideas where I can buy RF fuses, either the actual fuse element or the combination holder/fuse say in a BNC configuration, to portect the input of a spectrum analyzer or service monitor? Dave WB2FTX Yahoo! Groups Links
