Re: How to use a VGA monitor with your broken HP gear
Great info! Nice to know whenever my screen finally fails
Greetings from Brazil
I don't know how offtopic it is here. But I believe it must help someone
here
73 de PU2SEX, Alexandre
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How to use a VGA monitor with your broken HP gear
Greetings from Brazil
I don't know how offtopic it is here. But I believe it must help someone here
73 de PU2SEX, Alexandre
--
---8<---Corte Aqui---8<---
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Re: Why use a purpose built repeater box as a repeater rather than a transmitter, receiver, and controller tied (lashed) together?
Frank Perkins wrote:
"Just another note about using mobile radios in a repeater. Yes, their IFs were wide (stagger-tuned) to allow good function across the band coverage.
However, since in single-frequency repeater use, all that is needed is to sharpen the tuning to greatly improve selectivity and sensitivity. Same with the front end.
Thoughts?"
-------------------------------------
Thoughts?? Yes.? Could you list some of the FM mobile radios that use stagger-tuned IF's that you can sharpen the tuning to greatly improve selectivity and sensitivity?
Also, it would be interesting to see a page of alignment instructions that explain how to stagger-tune the IFs for good across the band coverage.
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Re: Why use a purpose built repeater box as a repeater rather than a transmitter, receiver, and controller tied (lashed) together?
Hi Frank and the group,
About three years ago I put together a "Low Bucks" repeater (UHF), using two GE "MVS" radios. Kept each radio intact and used the option cable to all input/output to an NHRC-4 controller. No tuning or mods to xmitter, and peaked the receiver for assigned frequency. Both transceivers fit into metal box. Controller (In aluminum box) is mounted on top of the radio(s) enclosure.
Even though the radios orig. were on 406 mHz (Low split) they work well at 443/448 mHz.(eighteen Watts to antenna)? The MVS is a great radio. Well built and cheap to purchase.
Of course I am using a fan on transmitter heatsink. After three years of service, NO PROBLEMS! NO DESENSE!
Tim AE7TH
Vashon Is Wa.
On 01/19/2021 8:49 AM Frank Perkins <n6ces.r@...> wrote:
?
?
Hi folks,
Just another note about using mobile radios in a repeater. Yes, their IFs were wide (stagger-tuned) to allow good function across the band coverage.
However, since in single-frequency repeater use, all that is needed is to sharpen the tuning to greatly improve selectivity and sensitivity. Same with the front end.
Thoughts?
Frank N6CES
roger that .
The old? IF? filters were wide.
?
?
Peter, Be careful on those old radios you mentioned. While I built many "IC-20" repeaters in the '70s that was when we had 30 KHz spacing between slots and they worked well. Presently, that won't work very well in a populated area with 20 KHz (or less-scary thought) spacing of repeater pairs. To get around that you could change out the IF filter as a bare minimum.? And, if you are in some third-world county with little to no repeaters around that may work.?
--
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
-
?
?
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Re: Tuning procedure for Mobile Duplexer TFE6030A
A couple further thoughts.?
The factory TX and RX markings are from the perspective of a mobile that transmits in the 459 range and receives in the 454 range.
Sweep it to see where it's currently tuned.? That's what you should see if it's unmolested.
Also, this duplexer may only have about 60 dB of isolation because the carphone receiver had a Motrac helical filter to add isolation.
Unlike a typical flat-pack duplexer that is designed for high isolation on a single frequency pair, the carphone operated on a range of frequencies.
Those extra adjustments could be for optimizing flatness across the band.
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Re: Why use a purpose built repeater box as a repeater rather than a transmitter, receiver, and controller tied (lashed) together?
Hi folks, Just another note about using mobile radios in a repeater. Yes, their IFs were wide (stagger-tuned) to allow good function across the band coverage. However, since in single-frequency repeater use, all that is needed is to sharpen the tuning to greatly improve selectivity and sensitivity. Same with the front end. Thoughts? Frank N6CES
roger that .
The old? IF? filters were wide.
Peter, Be careful on those old radios you mentioned. While I built many "IC-20" repeaters in the '70s that was when we had 30 KHz spacing between slots and they worked well. Presently, that won't work very well in a populated area with 20 KHz (or less-scary
thought) spacing of repeater pairs. To get around that you could change out the IF filter as a bare minimum.? And, if you are in some third-world county with little to no repeaters around that may work.?
--
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
-
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Re: Tuning procedure for Mobile Duplexer TFE6030A
Based on pictures I found online, that appears to be out of a 1970's era Motorola car telephone.? There may be tuning instructions in the service manual but finding a 40+ year old manual could be a challenge.
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Re: Another basic digital voice question.
Sounds like a job for DSD+
Will
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Show quoted text
On Jan 19, 2021, at 8:56 AM, Jim Barbour <wd8chl@...> wrote:
?This is a project I've been keeping in the back of my mind for a few years. I want to take a mobile (in this case, an M1225) that the tx is no good (no power out), hook it to an MMDVM, and let the radio scan (rx only!) the local city frequencies to ?then stream online. PD is P25, ambulance is NXDN, and the rest is analog. Can a MMDVM switch rx modes on the fly, including allowing analog, based only on the raw data it's receiving (not a question that I can find an answer to anywhere.)?
And before anybody says to just buy a scanner, 1) I already have one, and 2) I can't justify the cost of another one just for this. The radio is a freebie/junk, and an MMDVM is fairly cheap. Yes, a Kenwood mobile, like an NX-5730, would work, but those are vastly more expensive.
I'm assuming also the audio from the MMDVM would have to feed another box that handles the streaming...I have laptops...
-chl
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Re: Clamp meter mistake -- watch for a balanced meter movement if analog
I worked in a very large industrial plant.? In my tool box was a couple of Fluke meters and the good old Simpson 260 and Amprobe analog meter.? I most often grabbed the analog meters for quick tests and the digital if I really needed to be more accurate.? There are some things the analog meters seem to me to be lots better such as looking at quick moving spikes or drop outs.
I retired but have the same meters.? Just checked the Simpson and Amprobe.? ?The Simpson meter seemed very stable in all positions.? The Amprobe moved about two small divisions.? Almost not enough to be noticed for quick testing.
I have had some cheap meters and they will deflect a large ammount as they are rotated.
Ralph ku4pt
On Tuesday, January 19, 2021, 07:30:58 AM EST, Bob M. <wa1mik@...> wrote:
Way before everything became digital (because, as we've been brainwashed, digital is better), Amprobe was the leader in clamp-on ammeters. These all used analog D'Arsonval meter movements. Hopefully they were reasonably well balanced in that the readings did not change regardless of the orientation. These weren't terribly accurate, but 5-10% was adequate for the purpose.
_._,_._,_
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On Mon, Jan 4, 2021 at 09:44 PM, John Beard wrote:
Hello fellow repeater- builder group members.I have a Motorola micro 220mhz
repeater that I'm selling . If you have questions or would like pictures email
me off the list. Thank you?
Do you mean a Micor?
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Another basic digital voice question.
This is a project I've been keeping in the back of my mind for a few years. I want to take a mobile (in this case, an M1225) that the tx is no good (no power out), hook it to an MMDVM, and let the radio scan (rx only!) the local city frequencies to then stream online. PD is P25, ambulance is NXDN, and the rest is analog. Can a MMDVM switch rx modes on the fly, including allowing analog, based only on the raw data it's receiving (not a question that I can find an answer to anywhere.)?
And before anybody says to just buy a scanner, 1) I already have one, and 2) I can't justify the cost of another one just for this. The radio is a freebie/junk, and an MMDVM is fairly cheap. Yes, a Kenwood mobile, like an NX-5730, would work, but those are vastly more expensive.
I'm assuming also the audio from the MMDVM would have to feed another box that handles the streaming...I have laptops...
-chl
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Re: Clamp meter mistake -- watch for a balanced meter movement if analog
Way before everything became digital (because, as we've been brainwashed, digital is better), Amprobe was the leader in clamp-on ammeters. These all used analog D'Arsonval meter movements. Hopefully they were reasonably well balanced in that the readings did not change regardless of the orientation. These weren't terribly accurate, but 5-10% was adequate for the purpose.
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Re: TPRD-1554 Troubleshooting
I worked on a TPRD-4544 many years ago that was not tuning properly. I had a feeling the coax used to form the coupling loop was somehow defective. I ended up buying two new coupling loop assemblies brand new from Telewave. They had them in stock, complete, ready to screw into the cavities. I probably had to tell them whether they were for the high-side or the low-side, and the approximate frequency range, all obtained from the label. Something tells me they were around $50 each. I installed them, the duplexer tuned up perfectly, and exceeded specifications.
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Re: Why use a purpose built repeater box as a repeater rather than a transmitter, receiver, and controller tied (lashed) together?
3rd world? country? needs? some?? clarification??? these? days?? ?
toggle quoted message
Show quoted text
Peter, Be careful on those old radios you mentioned. While I built many "IC-20" repeaters in the '70s that was when we had 30 KHz spacing between slots and they worked well. Presently, that won't work very well in a populated area with 20 KHz (or less-scary
thought) spacing of repeater pairs. To get around that you could change out the IF filter as a bare minimum.? And, if you are in some third-world county with little to no repeaters around that may work.?
--
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
-
|
Re: Why use a purpose built repeater box as a repeater rather than a transmitter, receiver, and controller tied (lashed) together?
roger that .
The old? IF? filters were wide.
toggle quoted message
Show quoted text
Peter, Be careful on those old radios you mentioned. While I built many "IC-20" repeaters in the '70s that was when we had 30 KHz spacing between slots and they worked well. Presently, that won't work very well in a populated area with 20 KHz (or less-scary
thought) spacing of repeater pairs. To get around that you could change out the IF filter as a bare minimum.? And, if you are in some third-world county with little to no repeaters around that may work.?
--
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
-
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Tuning procedure for Mobile Duplexer TFE6030A
I picked up a UHF mobile duplexer at a hamfest several years ago and now have a project I'd like to use it with. When I go to tune it though I find that it has some slugs that I don't know the purpose of. It's the usual layout of 4 notch cavities that seem to tune as I'd expect with rods at the end opposite the input/output connections. What's got me stumped is that there are also 3 additional slugs on the connection end that I can't figure out. These are all in the "Receive" side of the duplexer. Anyone care to enlighten this old Ham? Can anyone point me toward some tuning instructions?
Thanks, Harvey WB5MCT
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Re: TPRD-1554 Troubleshooting
Jeff,
Thanks for you comments and especially for the cable lengths.
There was no evidence of arcing on the capacitor's body so I don't think it was damaged by a lightening strike.
Do you have any idea what the value and voltage rating of the capacitor should be?
And could you recommend a preferred vendor?
73 and aloha, Eric KH6CQ
On Sunday, January 17, 2021, 5:52:39 AM HST, Jeff DePolo WN3A <jd0@...> wrote:
> As received, each cavity was tested separately using a DSA815 spectrum analyzer with tracking generator and a high quality 50 ohm load. > The insertion loss of each was 0.7 dB and the notch depth was at least -35 dB. 35 dB notch depth is a bit low with loops set for 0.7 dB IL. > Touching the trimmer with the insulated tuning tool caused the notch to flatten out at about the 15 dB level. That indicates the capacitor is shorting out.? Piston trimmer caps are rather fragile beasts.? There are several concentric plates in the piston and stator.? The slightest eccentricity will cause them to short.? It is almost guaranteed to need to be replaced.? You can unscrew the rotor all the way, and, using a magnifying glass, look closely at the plates on both sides.? I bet you'll see either a slight distortion, pit, or something that will be the reason for it shorting out. > I'm also curious about the cable lengths. The inter cavity cables are the same length for both the transmit > and receive branches. They are RG-214 precisely 12.125 inches long measured tip to tip. > I would have expected the lengths to have been slightly different because of the different frequencies, > but maybe at a 600 kHz split the difference is negligible since it's only about one tenth of an inch or less. Comments? Between adjacent cavities - cable lengths would not vary because the frequencies are so close.? Between cavities and the antenna tee, the correct length is a function of Z of the opposing cavity at its notch frequency (i.e. at the opposing side's pass frequency), with the goal of rotating that Z to be back at the T to make it appear as an open circuit.? Many times, but not always, the lengths to the tee end up being equal. >? The other length I'm curious about is what Telewave refers to as the phasing cables. These are the cables > between the cavities and the antenna TEE. Their documentation states these cables should be > 1/2 wavelength at the reject frequency. Telewave is decidely wrong.
> The lengths of the RG-214 cables on this duplexer are both the
> same and only 13.5 inches long tip to tip.
> These seem way short since 1/2 wave cables at these frequencies is 26 inches and change. Comments?
Optimized cable lengths for the ham band: Between cavities:? 12.125" RG214 tip to tip Tee to first cavity on each side: 12.625" RG214 tip to tip The latter works out to about 84 degrees...nowhere near 180 degrees. ??? ??? ??? ??? --- Jeff WN3A -- This email has been checked for viruses by Avast antivirus software.
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Re: Clamp meter mistake -- watch for a balanced meter movement if analog
Thanks, Mike for the clarification. I have not seen clamp meters with the mechanical movement; all the ones I've seen have a digi screen. But the former is good to watch for dips and spikes :)? Good thread.
--
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
-
|
Re: Why use a purpose built repeater box as a repeater rather than a transmitter, receiver, and controller tied (lashed) together?
Peter, Be careful on those old radios you mentioned. While I built many "IC-20" repeaters in the '70s that was when we had 30 KHz spacing between slots and they worked well. Presently, that won't work very well in a populated area with 20 KHz (or less-scary thought) spacing of repeater pairs. To get around that you could change out the IF filter as a bare minimum.? And, if you are in some third-world county with little to no repeaters around that may work.?
--
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
-
|
Re: Low Band Motorola Base
Hi Mike,?
Please email me direct:
radio5000 (at) aol (dot) c o m
Thanks,
Will
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On Jan 18, 2021, at 8:40 AM, MIKE CHRISTIE via groups.io <MZFB@...> wrote:
?I would be interested in the PA only I could use it for a spare for my 6meter repeater. What would you want for it.
Mike
W1ZFB
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Alexandre Souza
Bob M.
Karl Shoemaker