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On Sat, Mar 30, 2024 at 06:27 AM, Clyde K2UE wrote: > > <Generally speaking there are two types of tube transfer characteristics: > > <The optimum characteristic can be described as two straight

I will add here that I have seen the band oscillators fail to oscillate due to a bad chassis connection to the variable inductor. Wiggle the top part where it connects to the chassis to see if you can

For those that missed it, the full story is here under the heading 'A Common "Bad Grid Idea" Super Cathode Drive' : https://www.w8ji.com/vhf_stability.htm TLDR text below. Visit the web page to see

Also C307, C310, and C309. Especially C307 which is ceramic. I may have already replaced that one in one of my rigs. 73 -Jim NU0C "Jim Shorney via groups.io" <jimNU0C@...> wrote:

I was also thinking of a Poly cap for C314 at the input of the mic amp circuit. This might not be the best place for an electrolytic. Definitely do not use ceramic. I have heard the effects of a

Hi, Mark. It has been along time since I looked at the innards of the TR7 so I cannot speak from recent experience. In particular, look at the coupling capacitors in the TX audio chain. If there are

Drake, heath, Henry, Kenwood, etc, all did the same thing.? It was a stupid idea, right outa the gate...and doesn't work anyway.? ?IF you want say 10 db of IMD reduction, you require 11 db of

Interesting. It seems logical that a low resistance across the mic input would swamp and noise coming in at that point. But the question is where is the noise coming from? I think I would disconnect

If you are looking for those funny little screws for the 7-Line end caps check your local Ace Hardware stores. Some may have them. Every store is different and inventory varies. Item 44671-N #4 x 5/8

If you have a general coverage receiver/transceiver, listen for the crystal on 21.5 MHz.? Take a wire from the receiver antenna input over to the TR4CW and place it near the crystal area. You should

Both can still be found. https://www.rocelec.com/global-search/MPN3404 https://www.rf-microwave.com/en/unitrode/um9401/power-pin-diode/um9401/ https://www.microchipdirect.com/product/search/all/um9401

Hi Bill, Try this https://www.af4k-crystals.com/ 73, Jim VE1RB

Glenn, Thanks for the data. I will be looking out for PIN suitable for the TR-7 for my spares draw. The three 1N4007 I substituted for the RX input / TX drive steering PIN on the HPF board are working

Jim, Just put my later s/n (100xx) TR-7 on the bench, in place of the fixer-upper one, by way of a comparison. About time it saw some power! Carrier suppression on the later one is -60 dB and no trace

Hi Mark PIN diode inspiration: https://web.archive.org/web/20240330083557/https://www.frostburg.edu/personal/latta/ee/qsk5/schematic/MA4P4001B-402.pdf

That could be. One thing that web browsers do is a lot of disk writes as they cache web pages. 73 -Jim NU0C "Jeramy Thibodeaux" <kg4azt@...> wrote:

Generally speaking there are two types of tube transfer characteristics: The optimum characteristic can be described as two straight lines: constant transconductance at high input levels, and a second

40m is dead on my TR-4CW and suspect it may be the 21.5 overtone crystal. All other bands check okay. Any suggestions on who could supply me one. Tnx.....Bill wa8bda

Tom, My first thought was thinking a failing or undersized power supply.? Re-reading some of the responses I'm inclined to recommend trying these two things next (No Cost). 1. Hard drive defrag.

Yes, I was part of the discussion. I also posted a link to W8JI's engineering analysis that shows why the indirectly grounded grid circuit was a bad idea. The idea did not originate with Drake and I