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?? ?
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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: 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.
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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.
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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?
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: 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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Re: Low Band Motorola Base
Curious, how is it different?
It looks identical to me. ?
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On Jan 17, 2021, at 7:13 PM, Steve <petnrdx@...> wrote:
?Yes, the "intermittent duty" heat sink was a lot like the MOCOM.
But not quite.
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Re: Low Band Motorola Base
Mike,
There are no other modules. ?
Thanks,
Will
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On Jan 18, 2021, at 1:32 AM, M M <wa6ilq@...> wrote:
?If it's on 45mhz then it can go to 6 meters.? Crystals are available from Quartzlab.
Are there any modules hiding behind the test set?? (the speaker assembly)
I supect the cards include a squelch gate and a timeout timer and a line card.
If anybody wants to push it to 6 meters... well... I have a writeup on how to do it.
And a UHF or 220 MHz cross-link could be used to create a split-site repeater.
Mike WA6ILQ
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Re: Motorola XPR8300 repeater, no USB comms
Also to look at, is replacing the front display board (with the front panel LEDS) which affects both the USB and LAN connectivity. I've had to replace a number of these in the past on different XPR8300 repeaters. The USB interface controller resides on this board.
I've never seen Motorola provide a Field Service Bulletin on this issue, although I felt that they should have.
Paul Metzger
K6EH
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Re: ID-O-Matic IV Controller setup with Kenwood TKR-850
On 1/17/2021 11:52 PM, KD9QPL Piotr wrote: To make repeater work description states it is as simple as setting repeater as "duplex" and setting "COR" to Active HIGH.
I may be setting AUX ports incorrectly. Manual is not very helpful. I'm presently working on a TKR-750 now on the bench. That is the VHF cousin of the TKR-850. In the KPG-91D software you want to go to EDIT> FUNCTION PORT and select the AUX tab. I used the "AUX In/Out 6" output for COR and set mine to Active High. Look at the attachment. This comes out on pin 25. You will see that AUX In/Out 5 is programmed for TOR. You can use this output if you want PL and not just COR outputs. Whenever you are at a field that you want information, click on the box and hit the F1 key. This will give you information on that field. There is a nice Print feature that allos you to print out your setting when you are finished. That's how I printed out the attachment I sent. 73, Joe, K1ike
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Re: ID-O-Matic IV Controller setup with Kenwood TKR-850
Piotr, I would suggest that you use the TOR signal for your COS input to the controller.? It is a combination of COR and CTCSS, so you get the benefit of a slight delay (settable in the radio code plug) and fast squelch closure at the end of a transmission when the COS internal to the radio goes false.? When you program an auxiliary output for TOR simply set the true to a high output.
PTT is the EPTT signal input and it keys the radio when it goes to ground.? Use the TA and RA signals for audio as the receive audio is equalized and squelched and the transmit audio is equalized.? Be sure to put the radio in Duplex mode to disable the internal controller.
73 - Jim? W5ZIT
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Re: Low Band Motorola Base
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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Re: Why use a purpose built repeater box as a repeater rather than a transmitter, receiver, and controller tied (lashed) together?
Motorola service bulletin specifically stated that for 100% duty cycle
operation the R1225 High power repeater models were to be set to
operate at 25 watts max. output from the transmitter, not from the
duplexer output.
The Low power models that operated at no more than 10 watts were not
subject to this de-rating even though the heat sink was smaller.
Too many sales types never bothered to learn about the products they
sold. It¡¯s easier to sell a high power flamethrower than a properly
balanced system. And too many ¡°techs¡± were nothing more than
glorified installers.
In most situations a repaired R1225 repeater set at 25 watts with a
properly tuned duplexer (another big problem area) would easily take
care of the same coverage area as the 40 watt output.
A properly tuned notch duplexer had minimal insertion loss.
In 100% duty cycle operation the desktop case for the R1225 was
useless and often contributed to overheating problems.
A properly configured R1225 repeater was a very capable purpose built
repeater that was designed for on-site operations. Unfortunately far
too many were never properly set up and the entire line suffered.
Milt
N3LTQ
Quoting "fire22pa via groups.io" <fire22pa@...>:
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The r1225 is still not a 100% duty cycle machine. They have a week
spot at full power the solder melts on the final and causes a
failure we have on in service but cut back to 20 watts.
On Sun, Jan 17, 2021 at 8:25, Joe<k1ike_mail@...> wrote: On
1/16/2021 10:53 PM, TGundo 2003 via groups.io wrote:
To retort:
Many, if not most, current "factory" repeaters today are nothing more
than 2 mobiles in a box Not always true. For example, the Motorola R1225 repeater appears to be
a mobile, but the heat sink is much larger than on the regular M1225 mobile.
Joe
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ID-O-Matic IV Controller setup with Kenwood TKR-850
Does anyone have any experience setting ID-O-Matic controller. I have trouble getting my to work with Kenwood TKR 850 repeater.
To make repeater work description states it is as simple as setting repeater as "duplex" and setting "COR" to Active HIGH.
I may be setting AUX ports incorrectly. Manual is not very helpful.
Thank You for any feedback.
Piotr Latka
KD9QPL
WQYP964
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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?
I ahve an IC20? and? a few IC22As.
Looking at the? spectral output? of the? IC22,? it is very clean.?
I was impressed enough to keep a? few for our club's? repeaters.
It also has? helicals? ahead of the rcvr.
Some of that old stuff is? nice.
?
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Eric,
I've been building, modifying and servicing repeaters since 1977. I started out with the IC-20 radio in separate bud (radio) boxes. Built and my parent sold about 25 of them, some of them in other countries.
Also, controllers, auto-patch and many other projects. Many types, and brands, from a mobile to base commercial products.? Over the decades I've improved methods and specifications. I do it because I enjoy creating things to help others. Perhaps if you have
the time, check out my techi page for my story. The parent page has stuff too.? And, of course check out RB's page. Kevin and others have done a great job providing information for the amateur community. I refer to it often. Here's a shortcut to what I do.
https://www.srgclub.org/LinkRadios.html
--
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
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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?
Adam Farson? VA7OJ? gives an interesting? method? of? phase noise testing of? HF? receivers? with his? NPR method? .
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The Basics: Every amateur radio station should be provided with the following minimal test equipment: A frequency-measuring instrument accurate to within 10 Hz.
www.ab4oj.com
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What is the standard method to measure phase noise? Most measurement?systems have pretty wide skirts that seem to be phase noise generated by themself, not actual phase noise from the transmitter.
Would this idea work: Characterize a notch filter, calibrate the notch filter to zero it out so it is a flat line with the notch filter in place, and then transmit through the notch filter tuned for the transmit frequency?
?
Not unless you're talking about the PLL G.E. exciter.? In the offset frequency range of 12 kHz to 3 MHz a Kenwood TK-880 mobile has lower phase noise, as much as 20 dB lower at some offsets.
Bob NO6B
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Re: Low Band Motorola Base
If it's on 45mhz then it can go to 6 meters.? Crystals are available from Quartzlab.
Are there any modules hiding behind the test set?? (the speaker assembly)
I supect the cards include a squelch gate and a timeout timer and a line card.
If anybody wants to push it to 6 meters... well... I have a writeup on how to do it.
And a UHF or 220 MHz cross-link could be used to create a split-site repeater.
Mike WA6ILQ
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Bob M.
Karl Shoemaker
Paul Metzger - K6EH
KD9QPL Piotr