800 MHz receive module in Kenwood TM-733A
 

Thanks for putting this information on the net, even though it is 19 years old! I am wanting to buy a TM-710A and I'm trying to figure out how much the output power is so I won't over blow my amp!

On Thursday, August 11, 1994 9:01:23 PM UTC-4, Steve Haehnichen wrote:
Page 25 of the Kenwood TM-733A/E service manual has an interesting
diagram labeled:

800 MHz Front-End: KCB28 (Tx-Rx Unit B/4 IC202) Except K, P Type.
(What is type K, or P?)

It's an internal schematic of IC202. The external connections a
RF
E (10 of these, all grounded)
IF (MCF on schematic)
L0 (HET on schematic)
Vcc (80R on schematic)

From the 430 MHz module schematics, it looks like the RF line is
connected to the antenna via three capacitors (in series) and two
inductors (to ground). That small section is outlined with a dotted
box and marked "*B", leading me to suspect it's not installed on all
radios. Wouldn't be hard to add..

The MCF (IF) pin 7 is mixed into the UHF signal just before the BPF.
Pin 13 (L0, HET) goes into some kind of rectifier module I don't
understand. Pin 14, interestingly named Vcc and "80R" goes to Q203, a
power switching transistor, which is controlled by IC206, a "Shift
Register".

This Shift Register has outputs for:
14R (144 MHz?)
80R (800?)
43R (430?)
36R (360?, goes to IC203, "36RF", which seems to do 440 as well)
FAN (yep, Fan power transistor)
MID
NI (both go to Mid/Low switching)

Sooo.. I guess the questions that come to mind a
1) Do US radios have this 800 MHz module installed?
2) How does one ask the microprocessor to enable that output of the
shift register?

Happy Hacking!

-Steve "I'd never listen" Haehnichen

Steve Haehnichen Vigra, Inc. San Diego, CA
(619) 597-7080 x116 Fax: (619) 597-7094

What kind of amp are you talking about?

I'm not aware of any band plan that includes 800 MHz transmit for the amateur radio service!
There is a segment in the 900 mhz - but that is a horse of a different color.

If this is a USA comment, it would be illegal to use it on another radio service while using it for the amateur radio service.

The bottom line is - if you wanted to receive with it, you could do the same thing with most any cheap Uniden Bearcat type scanner.

Is this the modification you are talking about?
http://www.radiomods.co.nz/kenwood/kenwoodtm733.html