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Gonset G76

Discussion in 'Amplitude Modulation - AM Fans' started by N2DTS, Jun 4, 2019.

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  1. N2DTS

    N2DTS Ham Member QRZ Page

    The G76 is about the only vintage radio I am interested in owning.
    I had a few in the past and should have kept the clean one I had.
    I just got another one off ebay for a great price.
    I have worked guys using one that sounded great, and they reported even more power out then stock.
    Does anyone have any good mods for the audio?
    Someone had added neg cycle loading to the modulator, and it also sounded quite high fi.
    6DQ5 modulated by a pair of 6DQ6's, audio on the screens, grids grounded, zero bias triode connection...

    The little audio output transformer has a winding for driving the 6DQ6 screens.
    A 6CM6 does the audio output and driver job.

    The G76 does 80 to 6 meters, the touchy vfo does 80 to 10 meters, the ones I had were fairly stable but very touchy in tuning.
    The RX is nice, a 262 KHz IF gives nice selectivity, and you can adjust the shape by changing the resistors across the IF can coils, and the cap from primary to secondary.
    Removing or increasing the resistors increases the gain and narrows the IF response.
    The 5 pf cap from primary to secondary shapes the response as well.
    An SDR on the IF last section would allow one to SEE the shape of the IF response (and width) if you set the sdr to 262 KHz.

    Since its plate modulated, the little G76 can do 60 to 80 watts carrier output, depending on how hard you want to push it. Lots of grid drive and 700 volts on the plates gives good results, and the radio seemed to take abuse very well.

    I think it is a very attractive radio, and its super easy to work on, slide the case off and its all there.
     
  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Courtesy ""http://www.rigpix.com/gonset/g76.htm

    [​IMG]
    Type: Amateur HF/VHF transceiver
    Frequency range: 10-80 m/6 m
    Mode: RX: AM/SSB/CW
    TX: AM/CW
    RF Power output: ~60 W (100 W input)
    Receiver system: Dual conversion superheterodyne
    1st IF: 2.065 MHz
    2nd IF: 262 KHz
    Sensitivity: 1 µV (6 dB S/N)
    Selectivity: 3 KHz (-6 dB), 14 KHz (-60 dB)
    Image rejection: 15-80 m: >50 dB
    Voltage: External PSU (12 VDC or mains)
    Current drain: RX: Max 4.7 A @ 12.6 VDC
    TX: Max ? A
    Impedance: 50 ohms / ?
    Dimensions (W*H*D): ? mm
    Weight: 11 Kg (24.25 lbs)
    Manufactured: USA, 1960-196x (Discontinued)
    Other: XTAL or VFO. Noise limiter. 100 KHz calibrator. 6DQ5 final
    New price 1961: $376.25
    Related documents: User manual (3.6 MB), Schematics (1.1 MB)
    Modifications:
     
  3. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    Crystal control for the transmitter on 6-meters, no VFO on 6-meters.

    I had one for a short while. Then, a friend wanted it and had an excellent condition RME-6900 receiver for trade. Since I really did not use the G-76, I made the trade. We both were very happy with the deal.

    The VFO definitely requires a "light touch" to tune. However, AM is no where near as critical in tuning as SSB.

    Glen, K9STH
     
    N2EY likes this.
  4. N2DTS

    N2DTS Ham Member QRZ Page

    I think, back when this stuff was made, a vfo on 6 was just silly.
    I have an HA460 as well, and the vfo seems pointless, they just did not have good enough components I suppose.

    Be kind of fun to work a G76 to HA460 on 6 meters though...
     
  5. N2EY

    N2EY Premium Subscriber QRZ Page

    An interesting and somewhat unique rig from a transitional time in Amateur Radio:

    1) It's not really a "transceiver" in the modern sense. It's a transmitter and receiver in the same box with a few shared circuits. You still have to "spot" the VFO and the only shared RF circuit is the pi-network, which also functions as the input tuned circuit of the receiver.

    2) There are two front-panel band switches, and they are arranged opposite the usual order (most rigs have the bandswitch arranged so that frequency increases as you turn the bandswitch knob clockwise; the G-76 is the opposite).

    3) The tuning rate of both the receiver and VFO dials is REALLY fast. Clearly intended for AM

    4) Although the G-76 can do CW, there is no sidetone when sending and the selectivity is too wide for the mode.

    5) The G-76 was clearly Gonset's attempt to provide an AM alternative to the low-end SSB transceivers that were taking over the HF amateur market at the time, particularly for mobile and low-budget-phone use. AFAIK the G-76 is unique; no other HF AM station-in-a-box was ever produced for the amateur market.

    The only one I've ever seen up close was at Field Day 1968.

    73 de Jim, N2EY
     
  6. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    There were at least 3-each 10-meter AM units available but those did not have capabilities below 28 MHz. Those were the Heath HW-19 "Tenner", the Gonset G-28, and the LaFayette HE-50. Otherwise, for AM, besides the G-76, it was separate transmitter and receiver.

    Glen, K9STH
     
  7. K4KYV

    K4KYV Subscriber QRZ Page

    Ah, yes. The sideband-for-the-masses rigs.
     
  8. N2EY

    N2EY Premium Subscriber QRZ Page

    Yep. The early 1 and 3 band Swans, the Heathkit monobanders, the National NCX-3, the low-end Hallicrafters (SR-160?), and some others. Wildly popular due to their low price and simplicity of operation.

    And then rigs like the SB-100 and its descendants sealed the deal.
     
  9. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    Hallicrafters actually had 2 of the 3-band SSB transceivers. The SR-160 was one of those and the SR-500 was the other.

    WRL had the 80 / 40-meter "Duo-Bander 84" and the "Duo-Bander II". I have 2 of the "Duo-Bander 84" units that I inherited. However, true to Leo Meyerson and his acquiring parts from the lowest price source, the cabinets are completely different as is the tuning dial for the frequency control.

    Glen, K9STH
     
    N2EY likes this.
  10. WB2CAU

    WB2CAU Ham Member QRZ Page


    That 1961 price equals almost $3200.00 in today's dollar.
     
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