Re: [Repeater-Builder] Zetron 38A wanted in UK
Dave, I have a Philips badged version of the 38A in use on GB3DX to lockout audio on the main Rx when remote rxs are in use. The unit seems to decode into the noise more than any mobile/portable set. I think a spare unit is available- contact me off list. [EMAIL PROTECTED] Ian-G8PWE -Walsall www.gb3dx.com - Original Message - From: dave_g7uzn [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, December 24, 2004 12:41 PM Subject: [Repeater-Builder] Zetron 38A wanted in UK Hi All, I'm after a Zetron 38A contoller for a repeater project in the UK..Anyone got one lurking please? Cheers Dave G7UZN Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Transmitter combiners
Gareth, For two transmitters the length of the circulator to porcupine jumper would be 5/8 wavelength in coax. When these two are parrelled the common impedanceis 25+j25 ohm. Looking at the Smith chart it looks like a paralleled s/c stub of -j25 would acheive a match to 50 ohm. Putting these figures into lengths of RG213: Circulator to porcupine jumper0.85m s/c stub 0.58m I dont know how many transmitters you are combining,the stub impedance is -j16ohm for 3 transmitters and -j12 for four. There are lots of good transmission line calculators available on a google search. Ian G8PWE www.gb3dx.com - Original Message - From: Gareth Bennett To: Repeater-Builder@yahoogroups.com Sent: Saturday, November 27, 2004 4:11 AM Subject: [Repeater-Builder] Transmitter combiners Hi there Group :-) Is there somebody in the group who has knowledge on "Star" transmitter combining? I am trying to remember the formula for the "Tuning Stub" that also is fitted to the star, or "Porcupine" as we call them over here. All the stubs here are less than 1/4 wavelength (Including VF of cable)and as normal are shorted at the end :-) .. Everything else is as one would expect with the food chain going like this... Transmitter-Isolator-Cavity-"Porcupine" - Antenna. I want to tune this as best as I can, but don't want to spend large amounts of time hacking off coax :-) Any formula would be appreciated. I have tried to reverse engineer what we have in service to gain some formula, but nothing makes sense. Can anybody remember? Thanks in advance :-) _ Gareth Bennett This e-mail is confidential, if you received this message in error, or youare not the intended recipient,please return it to the sender and destroy any copies.Thank you. Yahoo! Groups Links To visit your group on the web, go to:http://groups.yahoo.com/group/Repeater-Builder/ To unsubscribe from this group, send an email to:[EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Repeater-Builder] synchronising slave transmitters to a master.
Has anybody on the group synchronised two or more transmitters together with a landline/RF link or done it digitally with a DSL/T1(E1) link ? How is it done? Ian Ashford G8PWE www.gb3dx.com Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Re Circulator
Andy At the risk of being obtuse, why did you adjust the receive port ? I assume the objective of your adjustment was to match the feeder to an optimised 50 ohm system. Using Xp and Xs in an L network between the feeder and the circulator as Eric suggests is one method. Another method is to adjust the port 2 (Antenna) matching for minimum tx power at the receive port. However as this is typically a single capacitor, some additional work with a line stretcher on your feeder would be required to obtain a true minimum. Ian Ashford G8PWE www.gb3dx.com - Original Message - From: Andy Hearn [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, October 08, 2004 12:20 PM Subject: [Repeater-Builder] Re: Re Circulator Andy Hearn wrote: HI I have just changed my 70 cm repeater antenna over to a co-linear 8 dBd gain, was running 2 full wave dipoles stacked (reason..antenna faults and not able to mount with correct vertical spacing). When I was calibrating the circulator on the bench, all set up perfectly, with the receive port being sharp in its setting. On site since the antenna was running a slightly higher VSWR compared to a dummy load (1.2:1), I thought it might be an idea to just tweak the receive port to optimise the rejection. However I found the tuning to be very flat, question, is this normal or am I missing something? 73 Andy G3UEQ Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Cavity filters from aluminium beer barrels ?
Dave. I have a couple of beer barrel resonators made in England by Aerial facilities ltd (Now gridcom) : A brand new barrel is silver plated then painted in grey etch primer/ gloss The old stainless -steel pickup tube and mounting plate is removed and replaced by a silver-plated variable length plunger of diameter 2 1/2 (It has to be this size because a beer barrel is quite fat and the Zo has to be about 70 ohm) The plunger is made of moving and fixed sections connected via a ring of fingerstock. An invar rod couples the moving plunger to the top locking collar which is part of the toplate. Two n connectors with 10 guage silver plated copper loops are fitted either side of the plunger. I have 70dB notch and 1dB insertion at 145.6/145.0 per cavity in antiresonant mode. My conclusion on Beerbarrels is that they perform well but are difficult to mount into a rack and a four barrel duplexer is too bulky. However they are cheap and fun to work with... Try Nu-Swift fire extinguishers on 70cm also. Ian G8PWE www.gb3dx.com Subject: [Repeater-Builder] Cavity filters from aluminium beer barrels ? Hi, Has anyone used beer barrels to make cavity filters ? Any info/designs would be useful.Cheers Dave Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Echolink - use as emergency backup receiver
We have recently had a couple of instances of severe interference on our repeater. 1)An energy saving lightbulb- acting as a -600khz transposer 200ft from our repeater. 2)A Dell computer monitor- again as a transposer, but very strong. Both instances took some weeks to DF and rectify. This repeater is internet linked and during the trouble we used a remote reciever via Echolink. Once the users had overcome the surprise of hearing their own voices at the end of an over, Echolink became a useful alternative to switching the repeater off. The remote Rx had the spare logic unit connected to it to provide ctcss and toneburst gating before onward transmission via VOX to echolink. DTMF functionality was a lost. I can see many other possibilities commercial and ham of remoting a receiver during periods of deliberate/accidental interference. Ian G8PWE www.gb3dx.co.uk Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Can I lose a cavity using an amp and an attenuator?
At the moment I am testing a 2m 4 can duplexer with a 25 watt transmitter and all is fine. I wish to remove one of the cans in the duplexer and use it for another purpose (part of another duplexer actually) If I lose a can from the tx arm can I "clean up" the transmitter with (say) a 120w solidstate amp followed by a high power 6dB pad? has anybody in the group tried this? Ian G8PWE Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
