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Search: Posts Made By: tripelo
Forum: Antennas 27-Jul-2020, 12:06 AM
Replies: 1
Views: 2,742
Posted By tripelo
JFD Antenna

Those may be spacers. The front elements are in a Vee array for UHF. The lengths of the UHF elements are 5/4 wavelength or possibly longer. The elements are relatively long for UHF and the spacing...
Forum: Antennas 15-Jun-2020, 5:46 PM
Replies: 33
Views: 3,349
Posted By tripelo
The Twinax is shielded twinlead. Like your 300...

The Twinax is shielded twinlead. Like your 300 Ohm twinlead with a shield. It could be useful in some situations.

It probably could be made to work for a half wave loop balun. but would...
Forum: Antennas 15-Jun-2020, 3:34 PM
Replies: 33
Views: 3,349
Posted By tripelo
Yes The 1st UHF transistor (BFG67)...

Yes



The 1st UHF transistor (BFG67) could be replaced with a BFG520.

It might lower noise figure a couple of tenths of a dB.

Prrobably need to retune.
Forum: Antennas 14-Jun-2020, 7:21 PM
Replies: 33
Views: 3,349
Posted By tripelo
Yes, plus. Channel Master and some other...

Yes, plus.

Channel Master and some other manufacturers have not provided accurate noise figure numbers.

Numbers often provided are quotes from transistor manufacturers specs.

There is more...
Forum: Antennas 12-Jun-2020, 10:18 PM
Replies: 33
Views: 3,349
Posted By tripelo
Yes, looks like it is. It appears L7 is...

Yes, looks like it is.

It appears L7 is meant to move to L7a location for the 0264 version.

Your preamp is probably newer.

.
Forum: Antennas 12-Jun-2020, 10:06 PM
Replies: 33
Views: 3,349
Posted By tripelo
There is no absolute limit relative to length. ...

There is no absolute limit relative to length. Probably way down the coax would have little effect. You will be limited by the length of coax to your preamplifier.

Two ferrites, next to the...
Forum: Antennas 12-Jun-2020, 8:29 PM
Replies: 33
Views: 3,349
Posted By tripelo
The graphs of ferrite impedance look OK for your...

The graphs of ferrite impedance look OK for your application.



They are a form of ceramic, if they bang against each other they crack and separate.



Merry is a good state.
Forum: Antennas 12-Jun-2020, 4:55 PM
Replies: 33
Views: 3,349
Posted By tripelo
CM-0264 Preamp

Seems feasible.

Main item is additional balun.

PCB traces are already there. Need to cut an etch connecting UHF & VHF, etc. Probably have to solder in a small jumper.

Maybe touch up...
Forum: Antennas 12-Jun-2020, 2:40 PM
Replies: 33
Views: 3,349
Posted By tripelo
Good morning Sev. The CM 0064DSB has...

Good morning Sev.



The CM 0064DSB has a regular ferrite 300:75 Ohm balun at its input.

The core and windings are seen in the lower right of this image (near input terminals).

...
Forum: Antennas 12-Jun-2020, 10:58 AM
Replies: 33
Views: 3,349
Posted By tripelo
Ferrite, Wavelength, etc.

Not clear how your choke balun is configured?

The choke balun does not make impedance transformation as regular 300:75 Ohm baluns would.

For example; two 300-Ohm antennas paralleled would...
Forum: Antennas 11-Jun-2020, 2:00 PM
Replies: 33
Views: 3,349
Posted By tripelo
Thanks for the RE report. Looks like you...

Thanks for the RE report.

Looks like you have several strong signal stations to choose from.




As you know, there are several other factors that affect received signal strength besides...
Forum: Antennas 10-Jun-2020, 3:19 PM
Replies: 33
Views: 3,349
Posted By tripelo
Bob, Interesting modification. Yes...

Bob, Interesting modification.



Yes true.

Still, every small, or not so small, amount of gain adds up.
Forum: Antennas 3-Jun-2020, 1:37 PM
Replies: 13
Views: 2,735
Posted By tripelo
Most antenna analysis considers the antenna is in...

Most antenna analysis considers the antenna is in free space.
That is far away from earth or any electromagnetic material (conductors in particular).

Stacking antennas close to earth (or...
Forum: Antennas 1-Jun-2020, 7:48 PM
Replies: 33
Views: 3,349
Posted By tripelo
Nice work, Bob. Wonder where you...

Nice work, Bob.



Wonder where you obtained the 'C' channel.

Wonder if Home Depot or Lowes has it?
Forum: Antennas 26-May-2020, 9:11 PM
Replies: 13
Views: 2,735
Posted By tripelo
Yes it might. Have examined a few of those. ...

Yes it might.

Have examined a few of those. Those examined here are not good quality.
The connection inside was pressure contact, probably very light pressure contact.

The parts that grab...
Forum: Antennas 26-May-2020, 6:09 AM
Replies: 13
Views: 2,735
Posted By tripelo
They? See one image. It is open combiner...

They?

See one image. It is open combiner case.

-------------------------------------------

There could be other difficulties, but a noticable one is:

A difficulty with combining UHF with...
Forum: Antennas 29-Apr-2020, 8:57 AM
Replies: 2
Views: 5,091
Posted By tripelo
Yes, could be Radio Shack antennas. In one of...

Yes, could be Radio Shack antennas.
In one of the VHF antenna images, can see a feature common to Antennacraft.
For many years, Antennacraft was owned by Radio Shack.



Yes, you are right,...
Forum: Antennas 21-Apr-2020, 4:00 PM
Replies: 1
Views: 1,319
Posted By tripelo
Probably Winegard (available in late 60s thru...

Probably Winegard (available in late 60s thru 70s).


http://forum.tvfool.com/attachment.php?attachmentid=3701&d=1587484030




Yes, looks like it is bi-directional.
Forum: Antennas 18-Apr-2020, 1:52 PM
Replies: 39
Views: 7,636
Posted By tripelo
Interesting idea, using RG8 with RG11 connector. ...

Interesting idea, using RG8 with RG11 connector.



Guessing from your image, probably RTV silicone would be a good candidate.
(Avoid silicone that contains acid, some use acetic acid, smells...
Forum: Antennas 17-Apr-2020, 6:50 PM
Replies: 3
Views: 1,327
Posted By tripelo
Conical Yagis

Yes.

It is a stacked pair of conical Yagis. Very popular TV antenna in the 1950-1970 time range.

The Conical Yagi covers both high and low VHF channels with moderate gain.

The conical...
Forum: Antennas 13-Apr-2020, 3:13 PM
Replies: 2
Views: 1,395
Posted By tripelo
It is probably an Amphenol VHF (both Hi and Low)...

It is probably an Amphenol VHF (both Hi and Low) antenna, or a clone. This is one of the first antennas to cover both Low VHF and High VHF. As marked in image below, it was available in 1951.
...
Forum: Antennas 11-Apr-2020, 5:27 PM
Replies: 39
Views: 7,636
Posted By tripelo
Thanks for the image. The location of the...

Thanks for the image.

The location of the single antenna may be a better location with respect
to multipath (likely ground reflections).

Best current guess; the problem is external and...
Forum: Antennas 11-Apr-2020, 1:35 PM
Replies: 39
Views: 7,636
Posted By tripelo
Reference 2nd and 3rd images in previous post: ...

Reference 2nd and 3rd images in previous post:

http://forum.tvfool.com/showpost.php?p=62791&postcount=8

Since the 'East Antenna Only' and the 'West Antenna Only' showed evidence
of phase...
Forum: Antennas 10-Apr-2020, 5:49 PM
Replies: 39
Views: 7,636
Posted By tripelo
The blue trace (antenna pair) shows a dip in...

The blue trace (antenna pair) shows a dip in middle of RF 8 spectrum.
That is indicative of two signals interfering with each other (out-of-phase).

An out-of-phase condition can result from:
...
Forum: Antennas 7-Apr-2020, 7:21 PM
Replies: 39
Views: 7,636
Posted By tripelo
Interesting project, Bob. Yes true. ...

Interesting project, Bob.



Yes true.

Many models that I have seen, especially at UHF, fail to account for everything that can affect results.
Partially because NEC2 makes it difficult...
Showing results 1 to 25 of 153

 

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