[AMRadio] Old Ham, New AM Enthusiast

[rbethman at comcast.net]

Larry and crew, 

That is a far more drastic method than I was thinking about. 

There is an audio mod for the TX-1 by W3SSC and another ham. 

The mod and schematic are on the Mods part on AMPhone.net, under mods. 

Then for an additional piece of help, the plate mod section uses a .1 ufd 1KV disc ceramic and creates negative feedback. 

I'll have to find the info in "my" archives as to the precise location. 

Bob - N0DGN 

----- Original Message ----- 
From: "Larry Szendrei" <ne1s at securespeed.us> 
To: "Discussion of AM Radio in the Amateur Service" <amradio at mailman.qth.net> 
Sent: Monday, December 27, 2010 5:59:39 PM 
Subject: Re: [AMRadio] Old Ham, New AM Enthusiast 

On 12/27/2010 1:24 PM, rbethman wrote: 
> Jerry, 
> 
> You are getting good advice - so far! 
> 
> One other made comment regarding the Apache. It has a "well earned" 
> nickname. * Scratchy Apache * 
> 
> It take a bunch of work reworking the audio circuitry to make it sound 
> like "you" REALLY sound. 
> 
> It also REALLY needs negative feedback added in. 
> 

I used to have an Apache. When I bought it, the modulators had been 
converted to triode-connected 6146s driven by outboard audio*. The thing 
sounded very, very good. The only thing that was used from the original 
Apache audio section was the modulation transformer, which isn't a bad 
piece of iron. 

*This is what the audio section looked like: 
-push-pull tube type audio output xfmr with 8 ohm speaker winding as 
audio input from external audio amplifier capable of at least 5-8W 
output. (original) high-Z primary ends go to 6146 modulator tube screen 
grids, and center-tap of this winding goes to ground. 
-6146 modulator control grids tied to about -5V bias, well bypassed 
for audio and RF, to put the operating point for the modulator tubes in 
a good place. 
-6146 plates to each end of mod tranny primary per usual arrangement. 
- voila! quick and easy good audio for the Apache! 

Having said that, though, I agree with Rob about focusing on the antenna 
first, and spend some time on AM before deciding what the "upgraded" AM 
station will be. 

Here are some AM nets up here in the Northeast you might be interested 
in checking into: 

AM Carrier Net, Sundays at 8:30AM on 3835 KHz 
Antique Wireless Association Sunday PM AM net, Sundays at 4:00PM on 3837 
KHz. 
Gray Hair Net, Tuesday evenings at 8:00 PM EST (or 8:30PM EDT) on 1945 KHz. 

73 and we'll be looking for you Jerry, 
-Larry/NE1S 

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